The gears of genius

TECHNICAL LITERATURE

10 IEEE SSCS NEWS Fall 2007

THE MIRACLEThe Square and Compass is a tinypub – well, actually, the only pub– in the sleepy village of WorthMatravers, nestled high on thechalk cliffs along the Dorset coast,looking out over the English chan-nel toward France. The CoastalHikers’ Guide says of this pub:“Fantastic place; geese runningaround; roaring log fires; bestscenery in the world; the friend-liest people; completely unspoiled;a gem”. Whenever I make a tripback there, the salty ocean spray,borne up on summer zephyrs,feels just as it did on my face dur-ing an earlier time, when electron-ics and I were both very young.

One evening in 1940, this pub -called “The Sine and Cosine” bythe TRE boys - was packed tocapacity. Its rustic tranquility hadbeen shattered by an influx ofhigh-spirited workers from a secretresearch lab (TRE) nearby. Theyhad good reason to be in a cele-bratory mood. Earlier in the day,Philip Dee, one of the engineers atthis top-secret development site,and on war-time loan from theCavendish Labs of Cambridge Uni-versity, received an ordinary-look-ing package from BirminghamUniversity. Its contents would havemade an alert espionage agentcrave for possession, had heknown it contained two precioussamples of a unique and radicallydifferent sort of microwave oscilla-tor tube: an invention destined tosharpen the eyesight of the olderChain Home UHF radar stationsscattered all around this coast dur-ing WW2, and radically shift thedynamics of this grim war [1].

Dee was filled with a mixture ofawe, elation and anticipationtinged with concern as he careful-ly extricated one of these strange,awkward devices, sprouting metalpipes for cooling and vacuum pull-down, a rigid coaxial line for itsoutput, and connections for DCpower. What he held was quiteunlike any other tube. For onething, it didn’t have a visible glassenvelope, so the inner structure

couldn’t be seen; and it needed apowerful magnet, as well as hun-dreds of volts at several amps, todo its special thing. In essence, itwas little more than an elaborationof the diode, the earliest and thesimplest of all electron tubes; butthat magnet introduced a thrillingtwist!

The boffins up north had waxedecstatic about its miraculous prop-erties; fitting, since Britain needed amiracle. France had already fallen,and the bombing raids all acrossEngland were intense. Dee mayhave wondered “How can yetanother type of valve change theoutcome of this endless conflict?”He could not have foreseen, noreven could Robert Watson-Watt,credited as the ‘father’ of radar (hewas later knighted for this work; hisfirst, pre-magnetron system dreamson in the British Museum, Figure 1)how such a naively simple devicecould not only win a war, but thatit would guide his seafaringthrough the darkest storm; that itwould become a key to forecastingthe weather and mapping theearth’s terrain and resources; that itwould one day cook our dinner inminutes rather than hours.

It was even less foreseeable thatits cousins, the klystron family,harnessing swarms of electrons ina game of electromagnetic give-and-take called bunching, wouldone day be used by the score toaccelerate particles almost to lightspeed in colliders, revealing layerupon layer of the complexity ofmatter as they hurtle, blind andthoughtless, head-to-head; and inan instant annihilate each other,

leaving just assorted fragments;much as do people in war. It wasbeyond imagination’s reach thatanother ingenious device, the trav-eling-wave tube, would be used todeliver movies produced anddirected by lonely robots rovingMars; or conveniently supplying uswith colorful coffee-table close-ups of Saturn’s rings and Jupiter’smoons; capturing visions of theawesome ever-humbling immensi-ty of space through Hubble’s eyes;or mailing the occasional postcardof some small, ignoble potato-objects boiling aimlessly in ourstar’s asteroid belt, harboring incli-nations to wipe out life on Earth,while a small radar silently meas-ures our space-craft’s closing dis-tance, as we test our propositionsto land on them, prod and pokethem, and report back on the stuffthey’re made of.

These amazing electron tubesprofoundly changed the face of civ-ilization, fully as much as would alater remarkable electronic innova-tion. No, this was not the acciden-tal discovery of minority-carrierconduction. In my own designexperience, the debut of discretecommercial transistors (BJTs) onlymodified the paradigms of designand manufacture; just as, later, glu-ing together four or five compo-nents into an awkward, one-off,and rudimentary hybrid proved lit-tle and changed nothing. Rather, itwould be a truly revolutionaryinvention: Jean Hoerni’s planarprocess [2].

But for now, in 1940, the onlyvision that mattered was that of anew hawk-eyed radar; and thisprimitive new device (Figure 2a)held that promise. The basic formof its internal structure can be seenmore clearly in a dismantled RAFmagnetron from a later time (Fig-ure 2b). We can imagine theexcitement felt by Dee as heattached the heavy magnet to thesteel flanges, with its focusingpoles carefully aligned to theupper and lower ends of the rod-like cathode, thus creating anintense magnetic flux along its

The Gears of GeniusBarrie Gilbert, IEEE Life Fellow, ADI Fellow

Figure 1: Sir Robert Watson-Watt’sbaby, dreaming contentedly in theBritish Science Museum of great days.

Fall 2007 IEEE SSCS NEWS 11


radial axis of symmetry. Whenpumped down to Birmingham’sspecified vacuum, he started theflow of cooling water, then appliedthe low voltage to heat the cath-ode, and made sure the anode waswell-grounded. Finally, with trepi-dation, he applied the supply-volt-age to the cathode; at first, perhapsonly a hundred volts.

As Dee inched up the supplyvoltage it seemed nothing remark-able was happening, except thecooling water was becoming veryhot. Then, at a critical voltage, hesaw the magnetron burst into oscil-lation. Or rather, he noticed thatthe RF test load, a bank of five orsix 100-W house lamps, began toglow. By the end of the day, usingthe full accelerating voltage recom-mended by its inventors, Randalland Boot, the microwave outputwas lighting up the laboratory likethe sun, while the cooling waterretreated to a much less threaten-ing temperature. The cavity mag-netron really worked!

The anode, a thick annulus ofsolid copper in which six cylindri-cal cavities had been milled, accel-erated electrons radially outwardfrom the cathode as in any ordi-nary diode. In the absence of amagnetic field these electronswould have hurtled directly to theanode, where they could only turntheir energy (momentum) into use-less heat (Figure 3a). But a mag-netron is no ordinary diode: itsmagnet forces the electrons to fol-low a strongly curved path; and byadjusting the magnetic and electricfields, they can be made to arriveat the anode’s inner wall travelingin an almost circular path, now

carrying their high energy in apowerful, swirling electron torna-do (Figure 3b).

Randall’s theory predicted thecavities needed a diameter of ~1.2cm to produce a 9.5-cm oscillation(f ≈ 3.2GHz). They act like micro-wave whistles: arriving electronsgive up some of their energy asthey blow across their open gaps,resulting in strong EM-fields inthese high-Q resonators that inter-act with the constantly-refreshedsupply of high-energy electrons,further reinforcing the RF power.This extraordinary behavior musthave astonished Dee, as ratherordinary DC volts and amps werebeing converted directly to puremicrowave power, and gushing out

of its coupler like water off a roofduring a tropical downpour. Greatingenuity had been poured intoprevious wondrous tubes, butnothing before the cavity mag-netron had provided such power atthese high frequencies – orders ofmagnitude greater than any previ-ous source – and with unprece-dented efficiency.

By pulsing the cathode supplyat a moderate rate, very narrowpulses of enormous peak powercould be generated. Soon, radarswould be using magnetrons oper-ating at 16 kV and an IPK of 8 A,thus accepting 128 kW peak DCpower, of which more than 50 kWwas directly converted to RF.These extremely-short microwavepulses would resolve far smallertargets than possible with moreprimitive UHF radars. At a strokethe magnetron transformed radarin a way comparable to convert-ing a pair of opera glasses into aspace telescope. It was thisprospect of super-accurate radarthat had created such high hopesat TRE that summer evening in1940, and provided an excuse forall the rowdy celebrations over atthe pub.

A FEARFUL PROXIMITY That same evening, barely farenough away to be insulated fromthe jubilance over at the Squareand Compass, Frederick ArthurGilbert, a serious and sensitiveman, and an accomplished classi-cal pianist, was diligently practic-ing a Beethoven sonata. A toddler,his third birthday just days before,squeezed alongside him on the

Figure 2: The cavity magnetron of Randall and Boot (now also in the British Science Museum) minus its magnet. (b) Aproduction magnetron disassembled to reveal the resonator cavities in the anode block.

a b

a

b

Figure 3: Electron flow in an 8-Cavitymagnetron (a) without, and (b) withmagnetic field applied.



black piano bench. He was doinghis bit to contribute to the unfold-ing invention, exploring the cack-ling potential of the top octaves:What If? this key? How About? thisblack one? All the while his father’splaying was weaving a complextapestry of enigmatic infinite loopsin this boy’s head, creating apainful confusion: What is music?

0 ∗ ∗ ∗ 1 ∗ ∗ ∗ 0 ∗ ∗ ∗ 1Two days later the piano, so

recently joyful, was in mourning.The latest round of bombs thatwere intended to destroy the olderUHF radar station at Ventnor, onthe Isle of Wight, or perhaps putan end to the magnetron work atTRE, missed their target. Instead,they hit our home town. I was thetop-octave augmenter: the last ofhis four children. By all the normalrules of nature, my mid-fortiesmother should have been excusedfrom further childbearing. Surprise!On June 5, 1937, two days after thedeath of Sir James Barrie, theauthor of Peter Pan, I showed up.

So my father named me Barrie,celebrating the creator of thisimaginary character, wishing thesame for me: that I might neverneed to grow up, and be forced todevelop my life in what was at thetime threatening to become theforeign occupation of England. Hedidn’t live to witness that darkprospect vanquished, or to playreal duets with me, sharing ourmutual joy of music-making likethe chromatic soul-mates wedoubtless would have been, per-haps striving to guide his new sonto make a mark on the world stageas a concert performer. What If?

Largely because of radar, andthe developments at TRE, a fewmiles from me, the War wouldeventually be won by the Alliedforces. But in those dark years, Iwas fatherless and my mother wasobliged to raise me and my sib-lings with zero income. Amongour few assets was the piano. Notbeing musical, she soon sold it, topay for necessities. So at a stroke Ilost both my teacher and thebeloved instrument that had oncesung for my chubby fingers, as Iadded joyfully to the fluid sonori-ties miraculously emerging frommy father’s hands. My sole inheri-

tance was a stack of sheet music.Some were his own hand-writtencompositions, but most were theworks of the great composers, lib-erally annotated in the garish pur-ple of the day’s ‘indelible’ ink:‘Legato here’; ‘Careful - suddenkey-change’; ‘Marked fff, but don’twake Barrie.’

A month after my father’s death,Aug. 12, 1940, a secret event tookplace that was nonetheless so rele-vant to my life that it might as wellhave been advertised in the Swan-age Times or the BournemouthDaily Echo. One of those primitivemagnetrons bounced a tentativepulse off the walls of the Normanchurch at St. Aldhelm’s Head, onthe Dorset coast. Satisfied with thisgeneral test, and perhaps as a wayto do some calibration, Dee’s teamturned the keen vision of theircontraption toward a passingcyclist and later, a small aircraftmiles out to sea. It was the firsttime a magnetron had been usedin a radar system; and the first timean aircraft had been tracked byradar. While this constructive workwas being pursued, three of theearly-warning stations in Kentwere again under attack; and afourth, the one at Ventnor, wasbriefly put out of action later in theafternoon. More bombings of thesestations were expected.

Inexplicably, Field MarshallGoering believed that these towerswere of no great significance, andhe redirected the bombing raids toinland targets, such as Coventrycathedral. The Enigma code hadrecently been cracked (with thehelp of the first programmable dig-ital computer, ‘Colussus,’ designedby Tommy Flowers, whom I’vehad the pleasure of meeting) soWinston Churchill knew about thisparticular air-raid, but he couldn’ttip his hand and reveal this knowl-edge. Many have said that if moreattacks had been ordered, andthose radar defenses weredestroyed, the Battle of Britainwould have been lost within onemonth. Instead, by July of 1941,the miraculous magnetron wasdoing its thing in Navy radar sta-tions, and shortly thereafter, in RAFaircraft. Earlier, in great secrecy,samples had been shown to a

group at MIT, and the US soonbegan to make their own mag-netrons. By the time they showedup to aid Europe, their militarycraft were also equipped withradar.

A DEARTH OF MENTORSIn his autobiography [3] theanthropologist Oliver Sacks tells ofa favorite uncle who encouragedhis curiosity about the worldaround him during his childhoodin the 1930’s. This fellow, whoowned a company that made lightbulbs (“We once used osmium forfilaments,” he said), spent a lot oftime with his young nephew, rev-eling in the magical properties ofbasic chemicals, especially crystalsand metals. His admiration for oneparticular metal led Sacks to namethis influential mentor Uncle Tung-sten. At a recent MIT event (H2.O),where Sacks happened to be thekeynote speaker, we talked aboutearly-life influences, and the enjoy-ment of our experiments inphysics and chemistry. The close-ness of our learning trajectorieswas remarkable, but the similari-ties ended there. Sacks was fortu-nate in having a highly attentiveand supportive extended family ofintellectuals and professionals, allof significant means. I had only myoverburdened mother, freshly wid-owed by the insanity of war, andshe was constantly broke. As theyoungest of her four children, Iwore ill-fitting hand-me-downsand repeatedly re-darned socks (alost art in the consumerist West).

So when asked “Who was yourmost influential mentor?” I’membarrassed (since many seemwell-prepared – even eager – toamplify this theme) in having toreply that I can’t recall there beinganyone of that sort. I was a lonewolf-cub, befriended only by ahyperactive urge to experimentwith everything. Without a fatheror an Uncle Tungsten, my child-hood inspiration came largely frommile-long treks to the nearestlibrary, where I found such deeplyinspiring works as Robert Millikan’saccount of his painstaking experi-ments for determining the mass-to-charge ratio of the electron, and



“Principles and Practices of Radar,”by Penrose and Boulding.

Even before I could read, andfor many years after my fatherdied, I browsed the enigmaticpages of his stack of music, myonly link to him, trying to makesense of their strange yet familiarsymbols. Neither my mother normy older siblings could help. So Ibecame a loner, guided by myimagination, in the company ofenigma, perplexity and hypotheti-cals. I began to formulate probingquestions. What If? we had notlived so dangerously close to theseradar stations, and TRE? What If?my father had lived? I felt sure mylife should be devoted to music, insome performing capacity, and atan early age, I resolved to earnenough to purchase my ownpiano. I eventually did, at 18, pay-ing by installments, and taughtmyself to play. Ironically, this play-ful instrument was made in Ger-many. I still have it, but I’ve sinceaugmented my arsenal with twogrand pianos (decked out asDisklaviers), and a farm of synthe-sizers, computers and perverselyexpensive audio equipment.

The magnetron was powerlessto avert the appalling loss of lifethat occurred in London later in1940, particularly during the incen-diary bombings of the night ofDecember 29. Not many yearslater, it was to be my good fortuneto be inspired by the war’s inven-tions. It was through radar, asmuch as anything else, that I gottangled up in electronics. Radarbecame my inspiring mentor. Thelinkage between its brilliantdevelopments, during my child-hood, and the numerous neatnotions of my own during adultlife are readily discernable. Thus,my explanation of how a mag-netron works will seem familiarwhen I later describe a semicon-ductor device, invented at Tek-tronix in 1969, to which it bearsan uncanny resemblance.

Such strong connectionsbetween creative events through-out one’s life are surely common-place; they are an aspect of whatmay be called the continuity-of-concepts principle – the fact thatmost of us have but a few seminal

ideas, forged at an early age, fromwhich we wring every ounce ofutility. Sadly, few of today’s youngcircuit designers, having acquiredmost of their knowledge fromstudies during school and universi-ty years, will have had the oppor-tunity to be exposed to such a richand varied set of formative experi-ences as were enjoyed by peopleof my age. The rare exceptions arethe practical experimenters, tinker-ers, who nowadays build robotswith microprocessors for brains,using analog ICs for augmentingthe acuity of their sensors and theprecision of power-control fortheir actuators.

TRANSFORMING LOSS TOADVANTAGEBut I’ve also learned, from conver-sations with people having a simi-lar childhood, that inventive apti-tudes often arise from the transfor-mative power of loss – the shock of,say, no longer having the compan-ionship of a parent during the crit-ical formative years, for whateverreason; and is even aided by theseverely limited resources associat-ed with poverty. Hiro Moriyasu, aco-worker of mine at Tektronix,was a prolific inventor. This frienddied in July, 2005. His obituarystates that in 1974 “[he created] oneof the first personal computers, theTektronix 4051, which caused IBMto take an earlier model off themarket.” As a boy, Moriyasu-sanlived in Kure City, Hiroshima Pre-fecture, until the shameful day theUS dropped the world’s first atom-ic bomb, surely mankind’s mosthideous perversion of technology.It appears he hid in a farm truckduring this terrible assault on thenearby community, and witnessedthe incredible devastation first-hand. Because of this tragedy, hewas raised by monks as an orphan.Luckily for Tektronix, he eventual-ly became a first-class engineer.

Yet, it’s not so very surprisingthat creativity may arise in adultlife when the infant mind is facedwith the perplexing meaningless ofgreat loss. Forced to accept enigmaas a normal and constant aspect oflife, and limited by a paucity ofmeans, the child develops prag-

matism and flexibility. Lackinghelp in making sense of non-lin-guistic symbolic representations,he acquires intellectual resource-fulness and independence of spir-it. Without the safe ingredients of anormal childhood, the young minddoes not simply make adjustments,to restore a neutral outlook: it mayover-compensate. It somehowmanages to extract strength fromloss, and gains the confidence to goit alone, fiercely vowing to be inde-pendent and copy no-one.

I find no reference to theseideas of early loss, deprivation orlimited means in any of the scoresof works in my own library con-cerned with creativity, nor certainother ideas about the wellspringsof invention; and although that’sanother story, here’s a tiny hint.Cortical neurons are undoubtedlysusceptible to electrochemicalnoise. What we call thinking is astream of controlled processes dis-turbed by stochastic mechanisms.Significant departures from deter-ministic, logical thinking caused bysuch neural noise may be moremeaningful to a mind familiar with– and even comfortable with – per-plexity, enigma and the dialectic,than one developed during a high-ly-structured and well-providedchildhood.

GROWING UP LEANBy about 6 years old, I was makingmodel airplanes from strips ofwood salvaged from packing-cases, begged from the local gro-cer. One served as the fuselage; asecond, nailed cross-wise, was thewing; and there may have been atail of sorts. Later, I built many fly-ing, floating and rolling machines;and I was also beginning to dis-cover, through my own What If?experiments, how switches, lampsand batteries behaved when wiredin various combinations. I made agame in which questions on oneboard were wired to their answerson another; completing the circuitthrough a wire placed on corre-sponding pads illuminated a lamp.

My curiosity soon embracedchemistry, initially using utensilsand common reagents from thekitchen; and electrochemistry,using batteries borrowed from our



rented radio-set. (Not having streetelectricity at that time, we usedonly gas-lights and candles, andthe house was heated in winter bya small coal fire in one room.Often, as I got ready for school,the bathroom window would becoated with ice. I wondered: Why?do the layers on the inside surfacemake beautiful fern-like patterns?).

One day, I wondered: What If? Iplace a pair of wires into this saltsolution and connect them to the120-V “HT” battery. Watching myjam-jar at an incautious proximity,I observed the reluctantly-electri-fied liquid was generating a green-ish slime and a cloud of gas. I haddiscovered chlorine. Incidentally, Irepeated this “experiment” whenat last we had street electricity, thistime using sturdy copper plateswired directly (!) into a 240-V ACoutlet. Luckily, the salt solutionmust not have been very strong,because it didn’t explode. But theliquid boiled almost instantly, andgreen gas proliferated. What If? Ismell this stuff, I asked. So I placedmy nose close to the fuming hazeof lethal gas. This was just one ofmany times during the next fewyears that I almost killed myself, byletting curiosity lead to recklessdisregard for the punch behind apower outlet, or for the internalenergy stressing the bonds in cer-tain nervously-bound substances.It is not wise to idly seek answersto the What If? question using liveammunition!

At about 8, using the metal gird-ers, plates, pulleys and gears of mygrowing Meccano set, I builtbridges, Ferris wheels, tractors,robots and steam locomotives.None ever came from How-Tobooks or magazines. It was anunspoken (and unbroken) rulethat the things I made had to beentirely the product of my imagi-nation. For example, a new modelboat might have begun as a solidbar of balsa wood. As I cut into itand removed pieces, a form beganto appear. Soon, the form wouldtake over, and from that pointonward, the knife was at the com-mand of the model: I merelywatched.

For better or worse, this stub-born independence has remainedwith me throughout my life. Even

today, solitude, a fresh pad ofinviting paper, a fine-tipped penand feline companionship bettersuit my temperament than life inthe madding crowd.

A novel IC product often startswith ideas of the How About? sort.I deliberately leave the detailsunstated: all options remain open.Working with the elements, I gen-tly persuade the product intoadopting a certain shape: thebroad outline of its function, andessential aspects of performance.At some point, a serviceable struc-ture appears; but I give it consid-erable latitude to guide me. I allowit to breathe; to talk to me. I listenfor signs of distress welling upfrom deep within its physics-bound heart, and attend to themright away. We work as a team, thestructure and I, in this fluid andcongenial fashion, always pre-pared to take big chances andmake major changes as unexpect-ed ideas for elaboration and refine-ment come along.

As the structure reveals its ownprimal shape, I’ll often allow thisto remain its form, even if differentfrom my original vision. Each IC ofthe hundreds I have designed wasshaped by forces deeper and rich-er than a one-dimensional list ofobjectives, even though thesemight have been subliminal guide-posts. What finally emerges, in thebest cases, is a well-balanced childof many such forces: a productwell-trained, disciplined in the pri-mary tasks it has to faithfully exe-cute during its life on a circuitboard, as learned by one deeplyinvolved with issues of usefulnessand suitability, not by the dictatesof an inflexible and heartless Prod-uct Definition.

RADIO AND TV EXPERIMENTSBy 9, electronics had become mydaily diet. I experimented withdozens of circuits, trying out newforms, blithely unaware of all theprior work. Replicating somethingfound in a magazine was no fun atall. A sufficient few of these HowAbout? circuits actually performeda useful function! This was how Idiscovered regeneration in a short-wave radio. I was too young tohave the knowledge or the

patience to perform a pen andpaper analysis before picking up asoldering iron. Initially, these cir-cuits used ancient components thatwere screwed down on to a thickwooden board, usually with anoth-er, thinner board forming a frontpanel for mounting switches, pots,lights and binding-posts. Thesereally were ‘breadboards’ (Figure4a).

In an early trial, in 1946, I wasexperimenting with a simpleamplifier. Its two stages were iden-tical, comprising a triode with aresistive load from the anode to+120V. A capacitor from this firststage coupled the signal to the gridof the second-stage triode (Figure5a). With my headphones connect-ed to the second-stage anodethrough a DC-blocking capacitor, Inoticed that touching my finger tothe input resulted in a hum, ema-nating from the neighbors’ AC sup-plies, mixed with the demodula-tion of the strongest of the AM sig-nals. (It was more exciting to con-

Figure 4: (a) In my natural habitat,the Happylab, about 1946; (b) Later,still there, probably at midnight,doing something gross to one of sev-eral home-brew TV receivers, 1951.My elder brother took these pix.



nect its input to the telephonewires on an outside wall of ourhouse. We had no phone. Theunused wires just hung alongsideother lines. But they often wereactive, and their inductively-cou-pled conversations were quiteclear; and often interesting!)

On this occasion, with questionsof the What If? and How About?sort sizzling in my head, I con-nected the output of this amplifierback to its input (Figure 5b).Immediately, the music on thefamily radio was hashed by fizzingwhistles. Tuning over the frequen-cy span of that receiver, I noticed“my” whistles came and went.More careful note-taking revealedthat these squeals were spaced atregular frequencies and appearedto form low-integer ratios. I acci-dentally discovered two things thatday: a basic type of cross-coupledrelaxation oscillator; and its abilityto generate not just one frequencybut many, in perfect ratios!

Later checking books in thelibrary, I found a similar circuit. Inanother of these books, I cameacross something wonderful calledthe Fourier transform, and realizedthat this was pretty useful, as itexplained the ratios in my scrib-

bled notes about that experiment.About two years later, I designedmy own multi-band superhetreceiver (Figure 6) learning entire-ly (although often painfully) bydoing. Below decks, it was a terri-ble “rat’s nest”; but it workedremarkably well!

I enjoyed many windfalls. Alady for whom my mother house-cleaned had also lost her husbandin the war, and he had left abonanza of 4- and 5-pin tubes,audio transformers, 3-inch longresistors that clipped into holders,fixed and variable capacitors, andother basic components, most stillin their original cartons; and scoresof spools of enameled copperwire, of assorted gauges, andgreen-silk-wrapped multi-strand“Litz” wire.

Another mecca was a radiorepair shop, run by a certain Mr.Sparks (I assumed that was his realname). He allowed me to rum-mage in a back room, a storehouseof beautiful old telephones andcrystal sets in walnut cases, withbright brass screw-terminals (I stillhave one – a GEC Marconiphone)and two- or three-tube “wirelesssets”, with fat tuning coils whosesturdy turns were held in place byheavy coatings of shellac, sportingebony panels and overly-preciseprotractor dials. Inside one was anodd-looking rotating spherical coil,which I was told was a “goniome-

ter.” Of course, I bought as manyof these treasures as I could afford.

Only a few years after the terri-ble attacks on Britain (and theequally terrifying attacks on Ger-many’s heartland), a glut of gov-ernment-surplus stuff appeared onthe market. Among my many treas-ures from that time were ‘rotaryconverters’ (small motor/genera-tors sets), electromechanical servosystems, IFF receivers and manystrange, exotic tubes. But it wasthe radar displays that were mygreatest inspiration. (Figure 7).One, an Indicator Unit 62A,included a 15-cm CRT and a feastof tubes; cannibalizing it and partsfrom a surplus UHF receiver, I builta TV receiver. Another providedthe 9-cm CRT which became theheart of my first oscilloscope. Iimmodestly note that both of thesewere entirely of my own design.Building something was as muchan adventure in learning as theprovision of a new tool for myHappyLab.

Oscilloscopes were to become aspecial fascination for me, trace-able to my exposure to these won-drous and enigmatic radar indica-tor units, and I designed several asa kid, experience that was to laterprove invaluable in industry. How-ever, until we got electricity in ourhouse, I had to carry the heavysteel chassis of my first TV receiv-

Figure 5: “Inventing” the classical mul-tivibrator. (a) Starting with this two-stage amplifier, I asked What If? theoutput is connected back to the input.(b) Lacking a ’scope, I learned the cir-cuit was oscillating only because of theradio interference it generated, theanode voltages being rich in harmonics.

Figure 6: (a) The top-side of my firstsix-valve superhet and (b) the under-belly – not a pretty sight!

Figure 7: “Some radar ‘Indicator Unitspurchased as WW2-surplus equipment.



er on the saddle of my old bicycle,which I pushed to the home of aschool-friend who lived about 2km away. Their house did havepower, and I painstakingly testedmy awkward contraption on theirkitchen table. The first time it wasplugged in, a spot of about 2 cm indiameter appeared at roughly thecentre of the screen. A propitiousstart, I thought; and back it wenton to the bicycle. Over the courseof numerous journeys, the spotbecame smaller and turned into ahorizontal line; the line eventuallyturned into a raster. One day, afteranother long walk to Mark Dore’shouse, the raster finally revealed asnowy picture. It was upsidedown.

EARLY “WORKING” YEARS At age 17, I started my first job, atSRDE (the Signals Research andDevelopment Establishment, Christchurch), as an “Assistant, scientific”in a group developing speech-encryption for narrow-band trans-mission. There I handled my firsttransistor, a frail point-contact typecosting the Government an armand a leg. It was one of three tech-nologies being considered toreplace the ECC81 double-triodesused in scores of shift-registers.The other two were trigger-tube orferroresonant flip-flops. In the end,none prevailed, and the next gen-eration of encoding systems woulduse miniature wire-ended vacuumtubes. This was fascinating andentertaining work. I recall buildingan 8-bit A/D converter using a spe-cial CRT with an encoded target.

But as a rookie in the job-mar-ket (to use today’s jargon) I wasnaïve about the full scope of thecharter at SRDE; and when, after afew months, it became clear thatsome very sinister military systemswere also being developed there, Iimmediately left. Later, on trial as apacifist, I was directed to work fortwo years in the local hospital, inlieu of military training. I providedgeneral patient care in a ward forthe elderly and the terminally sick.Many nights I would hold the handof a dying patient and the nextmorning prepare him for themorgue. But electronics kept pop-

ping to the surface. I made a sen-sor that clipped on to the glassdrip-window of an infusion set,and the associated circuitry, to dis-play the drip rate on Dekatroncounter tubes, and developedother sensors and displays to showvital signs. These simple aids couldnot be bought; medical electronicswas yet to become a business; andthe rotating plasma domain in theDekatron was to become animportant bridge between themagnetron and my carrier domainmagnetron, described later.

At the end of the two years ofmandatory service, my affectionfor the patients, staff and the hos-pital environment led me torequest a transfer to their surgicaloperating rooms. The work wasnot always charming: more thanonce I carried a warm, freshly-amputated leg to the incinerator.But during these two further yearsI developed electronic devices of aless trivial kind for use in surgery.And, incredible as it must seem, Iwas eventually entrusted to moni-tor patients under anesthesia,maintaining their critical parame-ters and the gas-flow rates, when-ever a major emergency led to ashortage of doctors; eventuallyeven inducing anesthesia withPentothal and Flaxedil (a powerfulmuscle-paralyzing agent). At othertimes, scrubbed-up and gowned,the surgeons allowed me to carryout minor steps in almost every

kind of surgery. Today, of course,any hint of such of thing would be,appropriately, a litigious causecélèbre.

Dragging myself from hospitallife with teary-eyed reluctance in1958, and back in full-time work asan electron-director, I found myselfat the part-time airplane companyVickers-Armstrong, I designedtriply-redundant PID systems usingearly germanium PNP transistors,for controlling the insertion depthof the critical moderator rods in anexperimental nuclear reactor at theAtomic Energy Research Establish-ment, located at Winfrith Heath,close to the same chalk cliffswhere the magnetron had causedsuch excitement 18 years earlier.AERE’s charter was the develop-ment of reactors for power gener-ation, of the kind later used wide-ly in Britain to provide electricity.

Seeing the need for a device thatcould detect trace amounts of leak-ing sodium, I proposed a detectorsystem that chopped light betweenan air sample in a tube from thereactor housing and a second tubefilled with outside air (Figure 8).Using synchronous demodulationand averaging over a very longinterval (many minutes), I figuredthis scheme should be able todetect trace amounts of sodiumvapor. No-one at Vickers showedany enthusiasm for the idea, so Ibuilt it. A need was recognized,and the solution provided, before

Figure 8: My leak detector monitored the status of a sodium-cooled nuclearreactor.



being requested, which I believe tobe the hallmark of the seriousinventor. Whether or not this is atenable position in these tiresomedays of what is called “market-driven innovation,” this has alwaysbeen my personal mantra, and wasto become an attitude I wouldencourage my team to adopt, andknown as ‘inciting to mutiny’ at theAnalog Devices NW Labs inBeaverton. Incidentally, this wasthe second-only remote design siteof ADI, established in 1979, thefirst being that archetypical one inEngland from 1972-77 – a riskystep that Ray Stata described in a1985 article in Forbes Magazine [4].

A MAJOR EPIPHANYAfter moving to Mullard, in 1959, Isaw a Tektronix oscilloscope for thefirst time. Its ergonomics, its preci-sion and ease of use inspired me todesign an entirely new dual-channelsampling plus real-time oscilloscopealong the same lines. I was neverasked to do this, but I believed itwould surely be needed soon, toprovide ‘millimicrosecond’ measure-ment capabilities (the ’scopes of theday were limited to a bandwidth ofabout ‘10 Mc/s’ with very poorgeometry, spot size and almost notime- and voltage-calibration) whileat the same time providing a usefuldemonstration what these thingscalled ‘transistors’ could do, first, bypublishing all of its circuitry in fulldetail in open papers, then using it todevelop faster devices and circuits.

The L362 was a crude yet trail-blazing sampling ’scope, based ona design by Chaplin and Owens ofthe Royal Radar Establishment thathad been commercialized byMullard. One is visible on the leftof Figure 9a. When it was learnedthat these oscilloscopes were fail-ing by the phalanx in the field, mypersonal rationale to build it final-ly came along, and no-one wassaying “No!” (nor even “Yes, goodidea!”). The failures were due tothe stresses caused by avalancheoperation of its germanium alloy-junction PNP transistors. Beingfamiliar with this mode of transis-tor operation, I was given the jobof “finding a quick fix”. Instead, Idesigned a radically new kind of

oscilloscope, closely mimickingthe appearance of the Tektronix545 scope, as a sort of homage, butalso to exploit familiarity and easeof operation (Figure 9b).

It was a rare occasion when I feltcomfortable about emulating a mas-terwork. Its designers evidently hadan exceptional understanding of theimportance of ergonomics in craft-ing the human interface – the “frontpanel.” The presentation of each ofthe functions (which were literallyat one’s fingertips, just behind eachknob) were very clear; the use ofcolor to identify these functions; the

way in which this ’scope faithfullyand precisely executed its promisedbehavior – all these were exempla-ry, and quite unprecedented. Myinterpretation of this was that thefolks at Tektronix had a deep empa-thy for the needs of the customer.This was a powerful object lesson initself, although it resonated fiercelywith my own passion to put elec-tronics at the service of people.

Whether designing systems,instruments or ICs, it is our job ascreative engineers to make cus-tomers’ lives a little easier, andtheir work more enjoyable. (In

Figure 9: (a) The L362 oscilloscope (on the left) and my own sampling oscillo-scope (on the right); a second plug-in can be seen. (b) Shows its similarity to thesuperb Tektronix 545 oscilloscope.



doing that, our lives will beenriched, too). A project must startwith such questions as: What MustBe? (that is, what are the externalrequirements and constraints thatput bounds on the project?); WhatIf? I put myself into their shoes:how would I like this new productto work? How About? adding [somefeature] to make it more useful? Inthis empathic approach to design,one constantly alternates betweenthe customer’s perspective – look-ing into the shop window – andone’s outward view from the back-room workshops of novelty.

The design of this oscilloscope(and later in life, of ICs) came outof that philosophy. To begin with,I decided it should look like a 545with the same familiar arrange-ment of controls and functions,allowing the user to immediatelyapply his knowledge about a simi-lar instrument of this sort and feelcomfortably expert. Thus, oftenthe customer was, and is, myself,whether designing an instrumentor a novel function IC. Later,Solartron made a hundred copiesof a sampling add-on unit Idesigned (described in the refer-ences) to functionally and visuallycomplement one of their low-cost30-MHz ‘scopes (top-centre, Figure8a).

Just as fine art and great musicprojects a sense of effortless simplic-

ity while concealing its complex rootresources and techniques, mydeceptively familiar-looking oscillo-scope was a very different machineinside. It used the same TektronixCRT and other parts, from the high-voltage-supply rectifier to theirunique ceramic component mount-ing strips and control knobs; and itneeded the help of a handful of‘valves,’ for example, as high-input-Z cathode followers and CRT platedrivers. But beyond that, it was fullytransistorized. One may wonderhow I pulled this off, in 1959-61since those early devices were pret-ty slow. But this is precisely thebeauty of the sampling technique: ina single step, it can transform giga-hertz phenomena into benign audio-bandwidth signals [5]. It is a sort ofmagic, a modern léger de main.

In the ‘Delaying’ mode, it oper-ated as a conventional (real-time)scope: just as in the Tektronix 545,this slower ‘B’ timebase could beused to precisely delay a trigger tostart the fast ‘A’ timebase, whosetime-range was shown by a gatingbright-up. When the ‘Delayed’mode was selected (or using the‘A’ timebase alone) this clevermachine seamlessly converted to adual-channel 700-MHz samplingoscilloscope, having the novelbenefit of high-impedance probes(all early instruments used 50-inputs). These probes included the

sampling gate proper and the cru-cial “strobe pulse” generator, usinga special transistor, the ASZ23, Ihad developed with the processpeople at Mullard, to operate reli-ably in the stressful, high-energyavalanche mode.

For the first time in a samplingoscilloscope, to my knowledge, aclosed-loop system was used toensure near-perfect linearity. Inthis scheme (Figure 10) the previ-ously-acquired sampled voltage isfed right back to the load side ofthe sampling gate – one step fromthe probe tip – thus predicting thenext output of this gate and allow-ing it to operate simply as an error-detector, affording a near-exactunity closed-loop gain. You couldcompare this to the operation ofan op-amp connected as a unity-gain voltage-follower, though witha more complicated forward-gainpath. It is also called a ‘slide-back’scheme, a reference to Kirchoff’spractical implementation of HunterChristie’s clever technique formeasuring a voltage to state-of-the-art accuracy [6]. It allowed theseprobes to make multi-digit voltagemeasurements at the node beinginvestigated, at any time-point onthe waveform, and display theseon an external DVM. Alternatively,the sampling channel could as eas-ily be used simply as an accurateDC “preamplifier” thus avoidingthe loading effects of a typical mul-timeter’s high input capacitance. Itoccurred to me at the time that itwould be wonderful if this digitaldata could be actually presentedright on the CRT – an idea thatlater saw fulfillment at Tektronix.

Early in this development, I dis-covered that by lowering the gainof the loop amplifier (AL), andexploiting the high correlationbetween adjacent samples in aperiodic-stationary signal (such asa stable-frequency sine-wave orpulse-train), the noise on a dis-played waveform could be greatlyreduced, at the risk of some time-smearing. As has often been thecase, the theory came later, and itis simple. So I exploited this, as auser-adjustable function, for eachchannel independently. Latercalled “smoothing”, it became astandard feature of progressive-

Figure 10: Sampling-scope processor using predictive feedback, novel in its day.



time samplers for averaging awave vector. An ingeniousadvance, the random sampler, laterinvented by Frye and Zimmermanat Tektronix, no longer requiredthe user to provide a pre-trigger inadvance of the waveform segmentof interest. This was a great stepforward. However, the randomlocations of the sampling instantspreclude the benefits of suchsmoothing.

I was understandably proud ofthese advances in oscilloscopedesign, much ahead of their time.Looking back almost 50 years, Iwonder where I found the energyto do it, single-handedly, but forthe invaluable help of an excellentmechanical engineer whose nameI confess to have forgotten. (Irecall he preferred the matureMahler’s 9th to my preference, atthe time, of the spooky nacht-musik of the 7th.) Its two,matched, high-bandwidth channelswith high-impedance probes,using the robust ASZ23 avalanchetransistor, for strobe-pulse genera-tion [7], the feedback samplingloop [8] the low-jitter timebase forreal-time sweeps and precise trig-ger delay, and its linear nanosec-ond-scale timebase for equivalent-time modes [9] – all requiredentirely new approaches. All of itscircuits were nonexistent transistortopologies in the 1960’s, and theyhad to be implemented using thelow-frequency alloy-junction tran-sistors of the time.

The Monsterscope had othertricks up its sleeve. Simply bypressing a button, an accurate,multi-color, plain paper copy ofthe waveforms appeared effort-

lessly on an analog XY plotter.This was yet another novel, andobviously valuable, operationalfeature stemming from the time-translation process (comparable tothe benefits of frequency-transla-tion in a superhet receiver). How-ever, it led me to stumble on anexceptionally powerful noise-reduction technique [10]. This wasan unintentional benefit of the tinyanalog computer (using the sameold PNP transistors!) which I hadinitially incorporated for the fol-lowing pragmatic reason. Conven-tionally, the equivalent-time sam-pling instant progresses at a con-stant horizontal rate across thewaveform, tracked by the X-loca-tion on either the CRT or the plot-ting table. An abrupt change, suchas the edge of a pulse, wouldcause the |dV/dt| of the time-transformed output to rise. Butvery rapid changes could not betracked by the analog plotter’s Y-axis servo, which first would beslew-rate limited and then severlyovershoot, causing the plottedwaveform to be seriously distort-ed. The problem could be avertedby using an extremely slow hori-zontal progression; but this was an

unsatisfactory way to cope with afew rare regions of rapid change.

The “analog computer” (Figure11, updated here with NPN transis-tors) subtracted a current propor-tional to |dV/dt| from the fixedcurrent which charged the capaci-tor in the plotting-specific time-base, which determined both theequivalent-time sampling instantand the plotter’s X-position. At apulse edge, the |dV/dt| reducedthe charging current, slowing theprogression of the samplinginstant. Consequently, the |dV/dt|dropped. The self-adjustingdynamics of this control systemresulted in the pen moving at aconstant scalar speed, whetherstrolling across ‘flatter’ regions ofthe waveform or climbing straightup near-vertical edges. The recon-structed waveform geometry wascompletely free of the usual aber-rations due to a plotter’s mechani-cal inertia. Another amazing bit ofléger de main, which could equallybe applied to the CRT display.

Here’s where some more magicmade a welcome appearance. Thisspeed-stabilizing process inciden-tally resulted in the transformedwaveform being trapezoidal in realtime. (Think about it). The glacialslope of this intermediate represen-tation of the waveform allowedheavy averaging to be applied withno smearing of rapid pulse edgeson the reconstruction; indeed, with-out being noticeable at all. Figure12 – an actual CRT photo and pen-plot, extracted from [10] – illustratesthe routine way in which this littleanalog computer exhibited mischie-vous disregard for the tyrannicalrule of noise and averaging statis-tics. The nonlinear averaging of thisrate-adaptive filter provides a farhigher degree of noise reduction,

Figure 11: This simple analog computer ensures high-resolution in plotter-gen-erated hard-copy.

Figure 12: Pulse details buried in a noisy screen display are clearly revealedusing rate-adaptive scanning.



over a given time interval, than ispossible by linear filtering. To myknowledge, this neat techniquehasn’t been used since, althoughmodern embodiments and applica-tions would be straightforward.

For example, in a conventionalspectrum analyzer, where the bandof frequencies of interest is progres-sively scanned at a constant rate, therepresentation of signal powershows many sudden sharp peaks.These often limit the permissibleminimum IF and video bandwidths,unless an inordinately slow scan canbe tolerated. But these are benefitsone may need to invoke: very lowreceiver bandwidths raise the resolu-tion acuity for tiny, narrow-band sig-nals nestling alongside much larger“interferers”, as well as reducing thenoise bandwidth. A technique suchas just described could be very use-ful. Likewise, when vector data ispre-stored in RAM, the rate of with-drawal can be controlled, and DSPcan perform the discrete-time differ-entiation of the signal.

High Jinx at TektronixMonsterscope had introduced severalbreakthrough in sampling scopedesign, and it became my opensesame to jobs in the US. In 1964, witha plane ticket to Hewlett Packard inLoveland, CO already in my hand, Iswitched preferences to Tektronix inBeaverton, OR (at a 10% lower salary)after an eleventh-hour phone-callfrom their VP Lang Hedrick. I joineda group designing sampling scopes(what else?), directed by the energeticNorm Winningstad. However, I wassoon invited by Wim Velsink to join anew team to develop an exciting fam-ily of laboratory oscilloscopes, Thisteam included a clever youngsternamed Les Larson, with whom Ienjoyed a close collaboration.

Out of this New Generation proj-ect came the acclaimed 7000-series:an ambitious design, with manyadvances in structure, function andimplementation. The first productwould accept four plug-in units.Numerous new plug-ins were to bedesigned. Of special note were theexquisite low-noise differentialamplifier with HP and LP filtersdesigned by John Addis, the ultra-compact dual time-bases and sam-pling-scope plug-ins (using two of

the available slots) designedfrom George Frye, Al Zimmer-man, and Gene Cowen. It was tobe permissible for any plug-in tobe placed in any slot, in anycombination: the 7000 had tooperate as “expected”. (Thus,one could swap the verticalplug-in and the time-base ifone’s head happened to be ori-ented 90° to the horizontal).

Furthermore, its back-plane/router (largely Les Larson’s work,with some involvement on mypart) needed to support very highvertical and horizontal bandwidths,since the plug-ins were expected toget faster as the years went by. The7000-series had to last forever!Such grand objectives made eventhe physical design of the back-plane – the mechanical interfacesto the plug-ins, the choice of con-nector types and the fixed set ofpin assignments extremely chal-lenging – quite apart from how thesignals were supposed to be rout-ed to all the right places! And allthis would, for the first time, makenear-exclusive use of TektronixICs.

These instruments would alsoextend the practice – first used inthe Tektronix 576 SemiconductorCurve Tracer – of showing themajor operating conditions, set upby the control knobs, in the samearea as the waveforms. HiroMoriyasu wanted to use bundles ofcoherent fibres, illuminated ineach plug-in unit by passing lightthrough characters printed on plas-tic discs attached to the mechanicalcontrol shafts. As these were rotat-ed, new characters would be pro-jected through coherent opticalconnectors at the interface to themainframe, then through morefibre bundles up to an area to theright of the CRT display. The plas-tic molding at the rear of theseplug-ins still included the 5mmholes where Hiro’s fibre bundleswere expected to go; an indicationof how close to production thisapproach had progressed).

While this scheme needed noextra “fancy electronics,” in analready complex design, I felt itwould be a mechanical engineer’snightmare, from the registrationtolerances at the interfaces, to the

snaking of dozens of fibre bundlesfrom the dense plug-in mother-board up to the front panel along-side the CRT. It was also hopeless-ly inflexible, for an instrumentintended to have a long produc-tion life. I frankly expressed theseand other concerns to Hiro, whowas, typically, quietly adamant thathis was the best approach.

I already had all the key ideasfor a novel, tight-knit set of ICs fora fully electronic ‘knob read-out’(KRO) system, that would adven-turously exploit the new possibili-ties opened up by custom analogintegration, using Tektronix’s newwafer-fab. But to prove the ideas Ihad to build a working demo. Thecrucial analog character “ROMs”(this was long before cheap ICmemories) were made using papercircuits! A resistive paper knownas Teledeltos (used for facsimiletransmission) formed resistiveboundaries onto which I placedmy “emitters” – blobs of silverpaint – whose physical locationformed a set of eight points foreach of about 40 alphanumericcharacters. In the demo, thesewere written on the same focalplane as the waveforms by furthertime-sharing the one CRT. Theydisplayed various operational set-tings, with independent control ofsize, style, position and brightness.

When I showed this to HowardVollum, Tek’s president, and oneof the founders, he was visiblyimpressed, and very supportive.

Howard was always an ardentand enthusiastic engineer, deeplyinvolved in the technical life of hisengineers, to the point of sittingdown with them sometimes overbreakfast at Tom’s Pancake Houseon Canyon Road and actually talk-

Figure 13: Howard Vollum (right) and I talkshop at Tom’s Pancake House, 1968.



ing circuits! (Figure 13). Whatpresident of a large technologycompany now has the time to dothat? (Answer: Every one of themhas exactly as many hours today asdid Vollum back then). Rather likethe Square and Compass was ‘theonly pub in town’ for the TREfolks, Tom’s was just about theonly restaurant in Beaverton, in themid-1960’s: close to the Tek cam-pus, to the Satellite Motel with itsgarish flashing ‘flying saucer’ sign,and to the little airstrip wheremany Tekkies parked their planes.We thought nothing of flying to thecoast, about 100 km west, for achange of scenery and a fully-stacked hamburger! We were allworking in new and unfamiliar ter-ritories, feeling our way forwardby instinct, rather than by refer-ence to maps. But I was now inthe hot seat to quickly deliver thiseleventh-hour readout scheme,and at low cost. In one unusuallyproductive year, I designed 15ASICs for this unique synergisticsystem. Its most interesting aspectsrelated to the design of the super-integrated character generators:the analog ROMs. These evolvedin form, becoming more effi-cient in their structure over threegenerations of fast prototypes [11].My decision to use fully-analogdata-coding also raised a lot ofeyebrows and was declared to be“unworkable.” (However, whenclothed in Teflon criticism-deflec-tors, it’s easy to respond to naysay-ers with an absent-mindedbemused smile). Two sets of ten-level analog-current sequenceswould access locations on a 10×10matrix; about 50 corresponded tocharacters, the rest were specialinstructions, such as those relatedto shifting the interpretation of thedata when attenuating probeswere added. (I learned recentlythat when these inscrutable 10-level data codes had to be adaptedto a new all-digital scheme forreadout, they caused immeasura-ble grief!).

In those days, the schematicswere hand-drawn on pale greenengineering pads, and handeddirectly to the small layout team.After only a few rough sketches,they picked up their “scalpels”

(Exacto knives) and began tomake cuts on the thin red-plasticfilm bonded to a stable mylarbacking. The maker’s name for thismaterial was Rubylith, so thesemasters were called “rubies”.About a dozen rubies were neededto define all the photo-layers forTek’s first NPN-only process, hav-ing an ft of 0.6 GHz. After cuttingthe polygons corresponding to onelayer of the final IC (say, transistoremitters) the red film in all theseregions had to be manually peeledoff, making many clear windows;then each was hung on a largeback-lit surface and photographedat ×500 reduction. It became thedesigner’s responsibility to checkthe accuracy of the rubies using amulti-color ×100 set of theseimages, overlaid in the actualsequence of process steps.

In this tedious process, errorswere easily missed. For example,the hundreds of 10-μm contactpolygons for emitters, as cutregions of film, were only 5 mmsquare on the ×500 rubies, andoften not stripped off. This over-sight could easily go unnoticed inexamining the ‘overlays,’ as a miss-ing 1 mm opening. An easily-com-mitted error, with disastrous conse-quences. But in spite of all thelabor-intensive steps in going fromHB pencil-lines to a complete andaccurate set of rubies, then the ICmasks and the waiting days inwafer-fab, first silicon invariablyworked well enough to be finalsilicon. On a wall at Tek whereLes Larson still works, he proud-ly displays the schematic of theirfirst production IC, the M001. The7000-scope took us up to aboutM059 (a 4-decade superintegrat-

ed counter/latch/quad-DAC ofmine, for a DVM integral to thereadout).

TRANSLINEAR TOMFOOLERYIn my spare time – my best times –at Tektronix I developed an exten-sive new class of current-mode cir-cuit-cells, based on what I laternamed the Translinear Principle[13,14], and also vigorouslyexploited what I called super-inte-gration. These included super-compact logic cells, a foretaste ofI2L [15], and an intriguing class ofsemiconductor devices based oncurrent domains – narrow, mobileregions of current injection whichcan be physically positioned on thechip either by magnetic fields orapplied voltages, to realize compo-nents such as solid-state poten-tiometers and common functionssuch as analog multiplication [15].Many of these inventions wereannounced in ISSCC papers, andto my surprise, they garnered aclutch of ‘Best Paper’ awards.

My first ISSCC paper [16] wasone such. It described some ideasthat are especially neat, and waslater expanded into a pair of JSSCpapers [17,18]. I am told thesewere the first JSCC papers to havebeen cited at least 100 times; andI’ve been asked to comment onthe impact of this body of inven-tions. One way to assess theirimpact is to note that for decadesthereafter scarcely an issue of theJSCC went by without at least onereference to one of these papers.Another is the fact that only todayI devised yet another uniquetopology within this tight genre of‘stem cells’. Yet another is to notethat, in my office, I have a do-it-

Figure 14: Transformations of the current mirror, leading to a new multiplier form.



yourself crystal-set kit, presentedto me on my 60th birthday, onwhose cardboard box a friend gen-erously wrote: “The only radio thatdoes not contain a Gilbert Mixer!”Let’s leave it at that; the truth isalways more nuanced.

Those early papers onlyscratched the surface. A muchdeeper lode was already beingmined, even as I wrote them,namely, the translinear gold-mine,although I coined that term later,and didn’t publicly advocate its useuntil 1975, in a brief ElectronicsLetters item. The ubiquity of theseideas quickly became evident, andled to scores of other papers, atfirst by myself, and later by others,including Evert Seevinck (I was hisPh.D. advisor) who added, to myinitial twenty or so basic translin-ear topologies, some ideas aboutformal synthesis; and with myagreement wrote the first book onthe topic [19]. Special Issues inmany of the Journals, and full Con-ference sessions, followed.

What was the Big Deal? Asmuch as anything else it was thearrival of ‘current-mode’ as an emi-nently practical and advantageoussignal processing paradigm,enabled by the BJT. As ideas go, itwas deliciously rebellious, andpotentially iconoclastic, while alsoof immediate value. More recently,I have tried to discourage the laxusage of the term current mode inpapers, since in practice, good cir-cuit design requires the use ofwhatever “modes” – and thus theprinciple state variables – as areappropriate at each stage of theprocessing chain [20]. However, sofar, my sage advice seems to havegone unnoticed! One can still findnumerous papers with titles like ANovel Current-Mode Filter; but no-one is staking claims to A NovelVoltage-Mode Filter. Yet both mustequally depend on the interchangeof voltage and current states.

The current-mode paradigm allstarted with the current mirror, acell that had no equivalent in vacu-um-tube design, mostly becausetubes are “depletion-mode”devices. Since a mirror accepts acurrent and delivers a current, andthe voltages associated with thecell are largely incidental, it was the

first genuinely useful current-modecell. Its “gain” is also described incurrent-transfer terms, and in thebasic form of the mirror, this isfixed by the ratio of emitter areas,A2/A1 (Figure 14a). In fact, it’s easyin principle to electrically alter thisgain (Figure 14b); but I was curiousabout another possibility. WhatWould Happen If? I were to set twomirrors side-by-side (Figure 14c)then, after severing the emitterbranches of just the output transis-tors from their roots, I enjoinedthem to hold hands, one-to-one? Amarriage made in Imagination!

My matchmaking efforts fostered aradically different cell concept: a newcreature. Two mirrors were trans-formed into a tightly-knit – indeed,indivisible and enduring – unit offour transistors. Now, the collectorcurrents IC1 through IC4 were forced tohonor and obey the (yet to be codi-fied and ratified) Law of Translineari-ty: which requires that IC1. IC3 ≡ IC2. IC4

under certain trivial and readily-metassumptions. In other words, herewas a circuit form that did notprocess signals as voltages mixed withcurrents, but thrived entirely on adiet of current-ratios. Such ratiomet-ric representations were a totally newsort of signal processing-paradigm.And that was the Big Appeal.

By casting the inputs IC1 and IC4 intothe complementary form shown,using the notion of a modulation fac-tor X acting on a fixed bias IX, andsupplying a tail current IY, we findthat Y, the modulation factor in theoutput, is simply identical to X , overthe full large-signal range -1 ≤ X ≤ +1.This identity doesn’t depend on IX andIY, nor the transistor scaling, nor thetechnology, nor temperature, nor (inmoderation) on supply voltages. Eventhe BJT’s finite beta does not impairthis identity! Viewed as a novel linearamplifier, the gain is simply the ratioIY/IX. No amplifier before (or since!)could claim to be linear to the extrem-ities of the signal range that is, fromthe limit X = -1 right up to X = +1. Fur-ther, by varying IY, we had an elegant,wideband, inherently linear two-quadrant multiplier. The extension tofour-quadrant operation was easy.

In fact, the actual trajectory of theinvention was slightly different. Itstarted with another rudimentarycell, the differential pair – the topol-

ogy assumed by Q2 and Q3 in Fig-ure 13 (c), once their emitters werejoined – which forms a crudetransconductance multiplier. Butthis cell is nonlinear with respect towhat may be called its “X” input, thevoltage VB2-VB3 (the tail current IY

being the “Y” input). I asked: HowAbout? using a similar nonlinear pairto cancel the inherent tanh form ofthis transconductance. (I refer to thisdesign-think as an appeal to a‘homeopathic cure’ – the eliminationof a cell pathology by appealing to amathematically similar one in aninverse mode). The first account alsoavoids any reference to intermediateand merely incidental voltages andthus holds true to a pure current-mode theme. And it demonstrateshow tiny gene-slips in the chromo-somes of an analog topology canstrongly impact the near-identicalmutant, having critically modified itsDNA (Design, Nature, Applications).

During a leave of absence fromTektronix (1970-77) to expose myyoung family to a taste of life inEurope, and before being ‘discov-ered’ by Ray Stata of Analog Devicesin 1972, to set up the first ADI remotedesign center, I took a job as GroupLeader at Plessey Research Labs,managing a variety of ambitious proj-ects. One was a holographic memo-ry: a translucent cube of about 25mm on a side was written by severallasers; we hoped to cram a gigabyteof data into it – unthinkable at thattime. To my surprise (and onlybecause the Department Head diedof a heart attack) I also briefly man-aged MOS memory development. Asthese became faster and denser, theholographic research was eventuallyeclipsed. Another of my projectresponsibilities was the developmentof a new high-speed optical characterrecognition (OCR) system. Its front-end image processing circuitry usedwhat I called multi-channel adaptivethreshold. (Today, these circuitswould be classified as ‘neural net-works’). The Plessey 4200 systemsthat were currently in the field had160 analog adjustments, each ofwhich needed an expert in the fieldto align. I insisted that a key objectivefor the new system (intended for theBritish Post Office) was that it shouldhave no adjustments. In the end,there was one: an iris in front of the



camera lens! In reading the addresseson sometimes fuzzy or faintly-typedenvelopes at very high throughputs,its recognition accuracy was the high-est ever reported.

I also had ‘spare time’ to designseveral communications ICs atPlessey. In one, an HF modulator, thedistortion generated by the DVBEnonlinearities of a BJT differential pairwere sensed as they re-appeared in adifferential cascode and applied to anauxiliary gm cell, which added cor-rection currents in anti-phase at thefinal output – a technique I namedfeedforward correction. Such ‘homeo-pathic’ techniques, first exploited inthe earlier “current-mode” cells atTekronix, addressed both the signal-dependent nonlinearities and themuch slower time-dependent VBEerrors associated with the power-induced temperature shifts in thesetransistors. They provide a goodexample of the “continuity of con-cepts” themes that permeate one’s life.

Incidentally, Plessey were hope-lessly unsupportive. They saw fitto ignore the patent disclosure Ifiled on those thermal correctiontechniques. And after having had apreviously-cleared paper submis-sion to the ISSCC accepted, theyrefused to pay for travel to theconference and a hotel. So I paidmy own way. Apparently shamedby this, they reneged a month afterI returned.

Later, back at Tektronix, I sharedthe thermal-correction concept andlater elaborations of the cells with PatQuinn. It became widely used toavoid the previously serious thermaldistortion in vertical (Y-axis) deflec-tion amplifiers, and known as theCasComp. Today’s BJTs, fabricated onsilicon-on-insulator (SOI) processes,exhibit thermal resistances often high-er than 10,000°C/W. Extraordinarycare is needed to combat the effectsof non-isothermal operation – one ofthe firm promises made by transistorswhen they first roamed the planet.Translinear cells fare especially badly:for IC = 1mA and VCE = 1V, the ΔTcould be 10°C; at, say –1.8mV/°C, thistranslates to a whopping –18mV ofΔVBE, causing a 2:1 current-ratio errorin a TL loop! This concern led me tointroduce thermal modeling into oursimulator’s BJT equations at ADI,about 20 years back, now standard

for all processes. It is sobering towatch the consequences of turningthe self-heating terms back on again,after briefly being off.

I had developed an excellent rap-port with ADI and a great respectRay Stata – an “engineeer’s engineer”like Howard Vollum – while design-ing the first laser-trimmed IC multi-plier (AD534), the first monolithicRMS-DC Converter (AD536/636),and first IC V/F Converter (AD537)[21, 22, 23]. But my life-long fascina-tion with oscilloscopes and myregard for Howard remained strong:now my loyalties were in an awk-ward tension. When the family trav-eled back to the USA, in 1997, thisangst compelled me to return towhat I had come to regard as myalma mater, Tektronix, where I feltthere was unfinished work to flushout of my system. Anyway, I couldstill “do ICs” there, I reasoned. (Mycar sports IDO ICS plates).

A LINK TO MAXWELL A memorable assignment took meback to the lair of Philip Dee (remem-ber him?) – the Cavendish Labs atCambridge University, to spend timein the company of the world’s largestvacuum tube, their 2-Angstrom elec-tron transmission microscope. Thismonster was nearly a metre in diam-eter at the viewing ports on theground floor. From there it rose upthrough three floors; at the top, thecathode was supplied with _700 kV,donated by a huge transformer andrectifier inside a shielded room.

My thing was to provide the elec-tronics to measure the cathode cur-rent. It used a V-F converter I haddesigned at Analog Devices (theAD537 – the first monolithic V-F, stillin the catalog). One of the usefulfeatures of this empathy-borne ICwas that I’d made sure it couldoptionally supply large currents toan LED at its square-wave output.The buzzing light then droppeddown through the three floors on athin glass fibre, to the workingdesks at the anode level where thescientists struggled to see Very TinyThings through very thick windows,fiddling with “my” cathode current,I suspect, in a struggle to improvethe contrast of these images.

Once, my host mischievouslydefeated the safety interlocks and

opened the door to the EHV roomwhile the supply was operational. Ifelt my hair being tugged forward bythe fringing field just outside. Withthe power off, and the interlocksagain grounding everything in sightit was safe for me to enter and workon the cathode-current monitor. Butof course, to make my calibrationadjustments, the microscope had tobe fully operational; so I blissfullytoiled in this little room at 700 kV“below sea-level”!

As an invited lecturer at Cam-bridge University, I was delighted tolearn that the classroom in which mytalks were to be presented was thevery one used by James ClarkeMaxwell, while teaching his newmathematical theory of electromag-netism. The musty atmospheredescended on me with the fullweight of history. The students’ deskswere the original ones, with initialsand other cryptic symbols carveddeeply into the noble dark wood, ris-ing toward the back from the speak-er’s level, and the long demonstrationbench, on which Maxwell rested hispalms in an earlier age. Standingthere, soaking up the vibes, and dis-missing my modern audience toinvisibility for a moment, I felt oddlylike a distant ancestor, William Gilbert(1544-1603), who wrote De Magnete,Magneticisique Corporibus and, blesshis wooly socks, coined the wordelectricity. In this venerable setting, Itook the opportunity to remind theaudience of the work ethic of anoth-er great electronics engineer, MichaelFaraday [24]:

“Faraday never could workfrom the experiments of others,however clearly described. He knewwell that from every experiment thereissues a kind of radiation, luminousin different degrees to differentminds… And here, for the sake ofyounger inquirers, if not for the sakeof us all, it is worth while to dwell fora moment on a power which Fara-day possessed in an extraordinarydegree. He united vast strengthwith perfect flexibility. Hismomentum was that of a river, whichcombines weight and directness withthe ability to yield to the flexures of itsbed. The intentness of his vision inany direction did not apparentlydiminish his power of perception inother directions; and when he



attacked a subject, expectingresults he had the faculty of keep-ing his mind alert, so that resultsdifferent from those which heexpected should not escapehim through preoccupation.”[emphases mine]

“MY MAGNETRON”I started this piece by describingthe marvelous magnetron. While atCambridge, one of my lecturesconcerned a superintegrated solid-state device which I had devisedand fabricated at Tektronix [25], buthad not yet tested. It invoked thesame intertwining of magnetismand electricity, and because of that,my blithe interlude with the ghostsof Maxwell and Gilbert was espe-cially poignant. In 1970, during theworking period back in England,samples of this carrier-domainmagnetometer (CDM) were sup-plied to Prof. Greville Bloodworth(University of York) and Prof.Henry Kemhadjian (University ofSouthampton), and later successful-ly demonstrated [26]. Among sever-

al Ph.D. projects spawned by thisconcept, Martin Manley providedan elaborate mathematical treat-ment of its temperature-dependentscaling coefficients, and demon-strated a robust compensation ruse.Sadly, he was killed in a car acci-dent far to soon thereafter.

The CDM was unique in twodistinctly valuable ways: first, in itsability to convert magnetic fieldstrength directly to frequency, byvirtue of a circumferentially-rotat-ing domain; second, in having anintegrating response, meaning thatin principle even the weakest H-

field caused a slow, but readilymeasurable rotation – a very lowfrequency output. Figure 15 showsthe principle elements of a repre-sentative device. A junction-isolat-ed disc of n-type collector is con-tacted only at its center, ‘1.’ Over it,and grounded only at inner contact‘2,’ is another disc, a p-type base;just inside its circumference is dif-fused an n+ ring emitter, contacteduniformly all around its perimeter,thus at an equipotential, beingbiased by a fixed current. Beyondthe p-base edge is a coaxial ring,another p-type diffusion, ‘4,’ alsocontacted uniformly around itsperimeter and biased by a fixedcurrent. This ring acts as the emit-ter of a lateral PNP, whose localbase is also the n-type collector forthe NPN section, and whose(inside) collector is the edge of thep-disc ‘2,’ which simultaneouslyforms the base for the NPN sec-tion. Notice that the only path forthe minority carriers (holes) issu-ing from this LPNP’s emitter isunderneath the NPN disc-base,where the sub-emitter (‘pinch’)resistance is very high.

Thus, even small currents fromthe LPNP in the vicinity of its emis-sion zone can raise the localizedNPN VBE thus raising its emissionexclusively in that zone. Althoughan elemental PNPN structure existsall around the circumference, onlyone confined region of intense cur-rent injection, ‘5’, can be support-ed. Since the currents IEN and IEPare finite, the spatial feedbackprocess is bounded (the PNPNloop can’t ‘latch up’); it serves onlyto force both n- and p- injectioninto a small angular range. This isthe carrier domain: a mobile fila-ment of current (roughly analo-gous to an ‘isolated north pole’) ofa few microns in length, flowinglaterally from the p-ring back tothe p-base. In a perfect world, thedomain would arise in a totallyrandom location at power-up; inpractice, it won’t. Either way, it isthereafter obliged to chase aroundthe circumference under the intox-icating influence of the magneticfield perpendicular to the page, ina tantalizingly-reminiscent fashionas did in ancient times those elec-trons grazing the anode rim of the

new-born magnetron, glowingwith self-satisfaction on Dee’sbench.

Just outside the p-emitter, Iplaced p-type sectors formingouter collectors, ‘6,’ in a locationanalogous to the cavities of a mag-netron; and while these are notmicrowave resonators, compar-isons to the magnetron are irre-sistible. After all, this CDM really isan RF oscillator, although unlikethe magnetron its frequency is pro-portional to the H-field strength,fulfilling its lesser destiny as an ‘H-f ’converter. Which is pretty neat;but beyond that, these things areinherently (and uniquely, I’m pret-ty sure) integrating magnetic sen-sors. Acting as it should, a domainwill stroll leisurely around this cir-cus-ring at a slow angular velocityeven for minuscule fields. Thedirection of its stately promenade,thus the field polarity, can besensed by the phasing of the cur-rent pulses generated by the outersectors, while its magnitude canbe ratcheted up in a counter.

Unfortunately (although pre-dictably) my first devices sufferedfrom a malaise I called ‘electrostic-tion’. Mask-alignment skews gavethe domain the determination towake up in its ‘home state’. Thisforced us to go chasing after a fewmega-Teslas to overcome its stub-born will, long before MRI-gradesuperconducting magnets came onthe scene. We finally did trackdown a cast-off from some earlyNMR work (really!), quietly rustingin a dark corner of the Southamp-ton University campus. This stick-ing-point was later addressed. Iasked How About? applying a largealternating field having a meanvalue of zero, exactly as I’d oncedone in my home-brewed tape-recorder to thwart magnetizationhysteresis in the medium. The netangular drift of the domain due toa small superimposed DC fieldshould now be measurable, usingup-down counters to integrate thepulses as it rushes in a CW- thenCCW-swirling tornado.

It worked! – thus making theCDM a viable integrating magsen-sor and the only such concept tohave been reported. Incidentally,when the magnetic field lies across

Figure 15: My “magnetron”: a super-integrated carrier-domain magne-tometer.



the device, it acts as an electroniccompass (and yes, the cosine lawbears on the frequency scaling inoff-perpendicular cases). I also

devised linear structures for oper-ation in a field-nulling feedbackloop to convert an H-field directlyto a proportionate DC current.Although this work was gleefullypresented in lectures all over themap, in memos, letters and peer-reviewed papers, none of it wasever patented, largely for lack oftime on my part. (Others gladlyrushed in to fill that vacuum). Theoriginal work has found its wayinto a 2004 textbook by G.W.A.Drummer of electronic’s mostnoteworthy inventions [27]. And,just as the terms ‘current-mode’and ‘translinear’ have been ram-pantly misapplied, it is regrettablethat so has ‘carrier-domain,’ beingused in subsequent work on lin-ear-mode (non-integrating) mag-netic sensors.

GLANCING BACKIt has been my good fortune tohave grown up through the mostprolific period of genius in elec-tronics: to have witnessed its majorinventions, not as a journalist, butas a user, being intimately involvedin exploiting them in numerousapplications; to have welcomedthe arrival of the first, fragile point-contact transistors, not in a news-paper headline, but as an experi-menter; to have immersed myselfin silicon technologies, reachinginto their rich treasure trove ofpossibilities, not by replicating theadvances of others, but as a stub-born and fiercely independentinventor. Today, much of what iscalled electronics is block manipu-lation and re-use. One needs toknow little about electronic funda-

ments to design many of today’s ITproducts.

Understandably (although regret-tably), few of today’s students ofmicrocircuits have a visceral aware-ness of the electronics of the pastcentury. So here’s a micro-history.Perhaps the most ingenious andseminal advance was the inventionof the triode tube, by Lee De Forestin 1906. However, we cannot saythat ‘electronics’ arose at that time.The word was not even coineduntil 1927, in an obscure profes-sional paper. In that same year,using a primitive ‘cathode-ray tube’,the Scottish genius John Logie Bairddemonstrated the first practical TVsystem (Figure 16). In 1930, SamWeber launched the influential peri-odical Electronics. Our journey onBig Maps had begun.

Baird’s TV was a profoundlyimportant milepost, by applyingtubes to a far broader scope offunctions than previously found intelegraph, telephone and radio. It,and radar, spawned clever circuitsof every imaginable kind for spe-cialized waveform- and pulse-gen-eration: all described for my boy-hood pleasure in the biblicalWaveforms [28], just one of thecornucopia of books in MIT’s Radi-ation Lab series, published afterthe war (1949). Many of these cir-cuits sported mystical descriptors,while others were weighed downby their names, some of portman-teau proportions (“Hey Joe! ThePhantastron sure beats the Pen-tode-Miller-Sweep-with-Integral-Suppressor-Grid-Gating!”). Just asany war has propelled technology,WW2 was the essential engine ofadvances in electron-beam optics,which would one day become theopen sesame to creating the ultra-fine spot-size of the magnificentCRT found in thousands of Tek-tronix 545’s; and one more, stealth-ily hiding in my monster-mutant.

From 1930 onward, technolo-gies for vacuum-tube and electron-optics developed rapidly, to abroad peak around 1950, duringwhich time numerous and diversetypes were developed, as thescope of applications grew expo-nentially. This progress radicallyexpanded peoples’ faith in scienceand technology, and expectations

of a coming dream-world, alreadyelevated beyond reasonable hopeof consummation. (Even washingmachines were hyped as“Designed for the Atomic Age.”Nowadays, we have “Digital-Ready” loudspeakers (?), micro-processor-controlled toothbrushes(?) and “Digital-” everything else,including digital war; while Par-adise is postponed).

In that same mid-century year,the transistor – the BJT – was gear-ing up to change the world evenmore dramatically. It’s known as aBell Labs “invention”, but its histo-ry is very different. First, it was anaccidental discovery of bulk con-duction, in their fruitless attempt todevelop a field-effect device [29],although an upstaged Shockleymust be credited with having pre-dicted minority-carrier transport.Second, merchant-ship wireless-telegraphers were experimentingwith HF oscillators (that is, withcircuits that require power gain)using two, differently-biasedwhiskers on a chunk of galena asearly as 1915 [30]. Third, therefinement and commercializationof transistor technology – theessential know-how of semicon-ductor processing, the growingawareness of the yield losses dueto particulate matter, the develop-ment of protective packaging tech-niques, and a better understandingof device behavior and the cre-ation of models – emerged incre-mentally over a period of manyyears, and was spread over manycompanies and universities. No-one was the “Father of the BJT.”

From 1955 onward, the use ofvacuum tubes declined; twentyyears later, they were practicallyobsolete. They now sleep in pri-vate museums, such as Prof. TomLee’s collection of 10,000 (andmine of about 100!). But the accu-mulated knowledge of managingelectron beams in a vacuum per-sisted. It was firmly establishedduring the development of special-ized CRTs for radar, television,oscilloscopes, medical-, analytical-and industrial-instrumentation, andcountless other information dis-plays; in the design of transmission(TEM) and scanning (SEM) elec-tron microscopes; in complex pho-

Figure 16: Scots Experimenter/Tinker-er/Inventor (ETI) Baird fiddles withhis CRT-based TV receiver (1927).



ton detectors equipped with high-gain secondary-emission multipli-ers for use in such applications asneutrino detection; in gas-filledvariants, such as the thyratron, oras gated-rectifiers using mercuryvapor, in power control devices(roughly doing the same as aCMOS switch in a regulator, butcontrolling a million times theenergy); and in huge triodes forgenerating the RF power used inindustrial induction heating appli-cations (frequently in semiconduc-tor processing); and in other exot-ic ways. Tube-museum web-sitessuch as [31] and [32] offer aninspiring visit.

While few of the small, ordinarytubes remain in use today, special-ized types continue to have greatpractical value, and in fact are stillbeing developed. Viewed asextended structures having a plu-rality of functionally distinctivesections, each of these cleverinventions is a System in a Tube(SiT?). From this modern perspec-tive, they bear a certain relation-ship to the contemporary analogSystem on a Chip (SoC). Of specialrelevance in this respect was thedevelopment of the traveling-wavetube (TWT) and the klystron, bothof which are RF power amplifiers.The reflex klystron, and the inef-fective and transitional split-anodemagnetron, which was soontrumped hands down by the pow-erful cavity magnetron – are RFpower oscillators.

These tubes deserve comparisonto the SoC because they co-inte-grate such elements, for example,as low-loss lumped-element trans-mission lines for velocity-matching(as in the TWT, and in theadvanced ultra-wide-band CRTsdeveloped at Tektronix) or theultra-high-Q resonators found inmagnetrons and klystrons. Thesemodulate, manage and magnifyelectron flow or direction in novelways. Formerly, in a vacuum tube,the only way to control this flowwas by one or more grids (six inthe octode). However, combina-tions of two, three or even fourindependent active devices weredeveloped, some with integratedpassive elements; others, such asthe “Magic Eye”, widely used as a

tuning indicator, integrated a vacu-um tube with a tiny phosphorscreen. A study of Adler’s 1946inscrutably-complicated wave-weaving Phasitron tube [33], onceused in FM broadcasting, shouldconvince you of the validity of the‘SiT’ notion – if it doesn’t leaveyour head spinning.

THE GEARS OF GENIUSThese experiences form a longchain whose links remain unbro-ken, and which is still growing inlength, sixty years after I becamean avid Experimenter/Tinkerer/Inventor –an ETI – in real elec-tronics: to wit, the analog domain,where circuit concepts andtopologies are Diverse, Dimen-sional, Durable and downrightDifficult [34]. This chain is an unin-terrupted continuum of constantly-developing knowledge, orbiting anucleus of only a handful of sem-inal themes. In today’s immenselycomplex world, few can hope toexcel as professionals in a broadrange of disparate endeavors.Most of us have just one bag oftricks. We reach into it numeroustimes, to again extract inspirationfrom our expanding museum ofideas; and each time we put anidea back into our bag, it will havebecome a little smarter, and shinea little brighter the next time itpops out.

I have three, maybe four, semi-nal themes: my daisy-chains ofconcepts. The chain magnetron-to-dekatron-to-carrier-domain-magnetometer provides a greatexample of the persistence-of-envisioning. They all involve elec-trons – sometimes as plasmas –that are persuaded to bunch inpreferred locations and thenrotate around a circular outerperimeter, where they do some-thing useful. For the first and thirdlinks in this particular chain, thepersuasion comes from a magnet-ic field. In the second, it is dis-crete plasma transference, insti-gated by clock pulses, and in thatregard it bears a closer resem-blance to another daisy-chain –the super-integrated string coun-ters of [14]. Indeed, it was myexposure to (and as a user of) the

Dekatron counter tube as a kidthat inspired the invention of thisand subsequent “string” counters(which are extremely efficient intheir use of chip area).

I suspect most careers are char-acterized by such ‘continuity phe-nomena’ as the daisy-chain-of-concepts, the persistence-of-envi-sioning and the little-bag-of-tricks.But these daisy-chains are gregari-ous: they intertwine. In my experi-ence, many of the resulting cross-connections have led to branchingideas of equally satisfying quality.

As well as these, we also carryaround in our head models –imagination-maps which give us asense of location, direction andintention. The topological map ofa metro such as Tokyo’s will seemarcane to the casual visitor: yet aresident must understand itsdetails, and the lines and stationsfor daily travel must be commit-ted to memory. However, if welike to explore the roads less trav-eled, to venture forth to an invig-oratingly different place, to risk,to remoteness, to travel upthrough Tohoku to Hokkaido,then a geographically-faithfulmap is indispensable.

Absorbing the key aspects ofthe metro map (many lines andstations may need to be ignored,for now) is like acquiring a firmfoundation in the fundaments ofelectronics. Numerous equations,criteria, methods, models andminutiae must be assimilated,filed and sorted in one’s mind.While many (say, Bessel func-tions) can be overlooked, fornow, all the rest must be distilleddown to everyday essentials.What is the noise-spectral-densityof a 50 Ω resistor at 300K? Whatis the value of the electroncharge? Why does VBE decline lin-early over temperature? Can itreally fall right down to zero, forpractical conditions? Such issuesmust be at one’s finger-tips, asnumerous individual, intellectualknowledge objects: but beyondthat, they must be integrated intothe instinctive, emotional fabricthat is your core being. You won’tget very far on the metro if youneed to consult the map each dayas you travel to work, and scruti-



nize every station-name beyondthe window as something per-plexingly new.

On the other hand, for mostETIs, a thorough grasp of thebusiness of contemporary elec-tronics – as a phenomenon, as anenterprise, as an industry, as acompetitive forum – comes slow-ly, and requires us to take somelong and lonely journeys on BigMaps. Like this one, articles in theSSCS Newsletter describing suchjourneys – situations encounteredin technical, business and emo-tional places very far from thereader’s own familiar landmarks,or the sentimental recollections ofsomeone else’s youthful adven-tures and irrepressible aspirations– serve to refresh us. Informed bythese vicarious expeditions, thereader can return to the detailedchallenges of daily work with anew perspective, a little betterequipped to examine issuesunder a brighter light.

Younger engineers: you’ll findthe world is full of naysayers, whoshould be firmly but politelyignored. Rebut the accepted wis-dom, but reserve respect for thewise. Understand the reason formy insistent repetition of thepower-questions What Must Be?,How About?, Why? (and Why Not?)and rising high above them all,WHAT IF? These are your launch-pads to novelty; they are your gilt-edged Invitation to Mutiny; they’reyour instruments of invention;they’re the primary drive-line gearsof genius.

Take big risks. It is to be hopedthat all the little histories of a thou-sand minor past-players such asmyself will add up to a powerfultestament to risk-taking. Withoutgoing out on a limb, novelty isunlikely to emerge from one’swork. Walk out onto the fragilecanopy of thin limbs as often asyou dare. You risk a breakthrough, and may be in for a bigfall; and what’s wrong with that, Iwant to know. Don’t wait to be toldwhat to do: do it anyway. Anyway,never do as you are told: or rather,do it only when it seems the rightand smart thing to do; then go100% beyond what you wereasked to do, and 200% beyond

what you were expected to do, and300% beyond what you thoughtyou could do, rising to the pinna-cle of what you really can do. Doit soon.

I’m starting to sound suspicious-ly syrupy, so here’s a soberingpost-script: In 1966, Sir RobertAlexander Watson-Watt, at age 64,married Dame Katherine Jane Tre-fusis-Forbes. Jane died five yearslater, leaving him hopelessly con-fused in a sea of jumbled memo-ries suffering from what was likelythe dreaded Alzheimer’s. A fewdays before Christmas, 1973, unno-ticed in a nursing home in Inver-ness, this Scot, this giant gear ofgenius, Sir Robert died alone. Bud-eri, in The Invention that Changedthe World, called him “a scientist, akind of philosopher, even a poet;and a bad businessman.” Nowthat’s an epitaph to live for.

REFERENCES[1] R. Buderi, The Invention that

Changed the World, Simon

and Schuster, 1996, p. 88.

Much of the information

came from this magnificent,

met icu lous ly - researched

source, which should be on

every engineer’s bookshelf.

Some embellishments of life

at TRE are mine, though with-

out compromising substantive

facts and dates.

[2] M. Riordan et al., Crystal Fire:

The Birth of the Information

Age, W.W. Norton, Co. 1997,

p.262.

[3] O. Sacks, Uncle Tungsten

Memories of a Chemical Boy-

hood, Alfred A. Knopf, 2001.

[4] Main, Jeremy, ‘A Chipmaker

Who Beats the Business

Cycle,’ Fortune, December 23,

1985, pp. 114-20, in which

Ray Stata talks about his

readiness to invest in Gilbert

“wherever he wants to live.”

[5] B. Gilbert, Sampling Tech-

niques Applied to High-Speed

Pulse Oscillography, Mullard

Technical Communications,

No. 48, pp. 317-329, June

1961. The rest of the work on

my oscilloscope project at

Mullard was not allowed to

be published until several

years later, each as the vari-

ous topics appeared to be

useful in promoting newly-

introduced transistors, the

actual mission of the MTC.

[6] Re: The Slide-Back Technique,

physics.kenyon.edu/Early_Ap

partus/Electrical_Measure-

ments\ . Also of interest: The

Bakerian Lecture: An Account

of Several New Instruments

and Processes for Determin-

ing the Constants of a Voltaic

Circuit , Charles Wheatstone,

Philosophical Transactions of

the Royal Society of London,

Vol. 133, 1843 (1843), pp.

303+, //links.jstor.org/sici?sici=

0261-523(1843)133%3C303%3

ATBLAAO%3E2.0.CO%3B2-0.

[7] B. Gilbert, Signal-Gating Cir-

cuits for Sampling Oscillo-

scopes, Mullard Technical

Communications, No 56, pp.

246 – 258, April 1962.

[8] B. Gilbert, Feedback Sam-

pling Channel for Sampling

Oscilloscopes, Mullard Tech-

nical Communications, No.

70, pp. 293-303, May 1964.

[9] B. Gilbert, Timebases for

Sampling Oscilloscopes,

Mullard Technical Communi-

cations, No. 67, pp. 211-226.,

Dec. 1963.

[10] B. Gilbert, An X-Y Plotter Sta-

blizing Adaptor for Use With

Sampling Oscilloscopes”,

Mullard Technical Communi-

cations, No. 74 pp. 90-104,

Dec. 1964.

[11] B. Gilbert, Monolithic Analog

READ-ONLY Memory for

Character Generation”, IEEE

J. of Solid-State Circuits, Vol.

SC-6, No. 1, pp. 45-55,Feb.

1971.

[12] B. Gilbert, Translinear Cir-

cuits: A Proposed Classifica-

tion, Electronics Letters, Vol.

11, No. 1, pp. 14 -16., Jan.

1975.

[13] B. Gilbert, Translinear Cir-

cuits: An Historical Overview,

Analog Integrated Circuits and



Signal Processing, Vol. 9, No.

2, pp. 95 – 118, March 1996.

[14] B. Gilbert, Superintegrated 4-

Decade Counter with Buffer

Memory and D/A Output

Converters, 1970 ISSCC Digest

of Tech. Papers, pp.120-121.

Feb. 1970.

[15] B. Gilbert, A New Technique

for Analog Multiplication,

IEEE J. of Solid-State Circuits,

Vol. SC-10, No. 6, pp. 437-

447.

[16] B. Gilbert, A DC-500MHz

Amplifier/Multiplier Principle,

1968 ISSCC Digest of Techni-

cal Papers, pp. 114 – 115,

Feb. 1968.

[17] B. Gilbert,A New Wideband

Amplifier Technique, IEEE J.

of Solid-State Circuits, Vol. SC-

3, No. 4, pp. 353 - 365., Dec.

1968.

[18] B. Gilbert, A Precise Four-

Quadrant Multiplier with Sub-

nanosecond Response, IEEE

J. of Solid-State Circuits, Vol.

SC-3, No. 4, pp. 365 - 373.

Dec. 1968.

[19] E. Seevinck, Analysis and Syn-

thesis of Translinear Integrat-

ed Circuits, Studies in Educa-

tional and Electronic Engi-

neering, Vol. 31, Jan. 1988.

[20] B. Gilbert, Current Mode,

Voltage Mode, or Free Mode?

A Few Sage Suggestions, Ana-

log Integrated Circuits and

Signal Processing, Vol. 38,

Issue 2-3, pp. 83-101, Feb.-

March 2004.

[21] B. Gilbert, A High-Performance

Monolithic Multiplier Using

Active Feedback, IEEE J. of

Solid-State Circuits, Vol. SC-9,

No. 6, pp. 364-373, Dec. 1974.

[22] B. Gilbert, A Monolithic RMS-

DC Converter with Crest-Fac-

tor Compensation”, 1976

ISSCC Digest of Technical

Papers, p. 110. Feb. 1976.

[23] B. Gilbert, A Versatile Mono-

lithic Voltage-To-Frequency

Converter, IEEE J. of Solid-

State Circuits, Vol. SC-11, No.

6, pp. 852-864. Dec. 1976.

[24] John Tyndall (1820-1893)

www.worldwideschool.org/li

brary/books/hst/biography/F

aradayasaDiscoverer/chap3.ht

ml\\ (Faraday quote).

[25] B. Gilbert, Novel Magnetic-

Field Sensor Using Carrier-

Domain Rotation: Proposed

Device Design, Electronics

Letters,Vol.12, No.23, pp. 608-

610, Nov.1976. Note: This the

title I used for this paper did

not tack on the last three

word, since I had not simply

proposed a design, but pro-

vided the devices originally

tested by Manley.

[26] M. H. Manley et al., Novel

Magnetic-field Sensor Using

Carrier-Domain Rotation:

Operation and Practical Per-

formance, Electronics Letters,

Vol.12, No.23, pp. 610-611.

[27] G.W.A. Drummer et al., Elec-

tronic Inventions and Discov-

eries: Electronics from its Ear-

liest Beginnings to the Present

Day, 4th Ed, Jan. 1997.

[28] B. Chance et al., Waveforms,

MIT Rad Lab Series, Vol. 19.

McGraw-Hill, 1949.

[29] B. Gilbert, Introduction to “The

Transistor – A New Semicon-

ductor Amplifier”, Proc. IEEE,

Vol. 87, No. 8, Aug. 1999.

[30] A. Emmerson, Who Really

Invented the Transistor?

under the section Oscillating

Crystals, www.porticus.org/

bell/belllabs_transistor1.html

[31] J. M. Harmer, www.tubecol-

lector.org/about.htm\\ The

navigation of this site takes a

bit of getting used to, but it’s

worth the effort. There are

almost 2,000 tubes in this virtu-

al museum; excellent photos.

[32] H. Dijkstra, members.chello.

nl/~h.dijkstra19/ A wonderful

tour of old electron tubes

especially relevant to devices

in the field of physics. Also

try www.roehren-museum.

de/englisch/user/home.htm//.

[33] R. Adler, A New System of Fre-

quency Modulation, Proceed-

ings of the I.R.E, and Waves and

Electrons, Jan. 1947. Complete

paper can be found at this web-

site: www.w9gr.com/adler.html/

For a modern presentation, by

someone who has re-built FM

exciters using this wonderful,

arcane tube, see www.w9gr.

com/phasitron.html/.

[34] www.analog.com/library/

analogDialogue/leif1.html//.

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The gears of genius