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HP 8971b 2-18 GHz NF test-set release 21F5DQK November 2010 part 4/4
Measures over 2 GHz with the HP 8971b
NF test-set extension
Version 2
HP 8971b 2-18 GHz NF test-set release 22F5DQK November 2010 part 4/4
Overview
1- Choice of gain/Nf analyser type:The AGILENT / HP 8970 gain/noise analyser family is limited to frequencies beyond 1.6 GHz.
- The HP 8970a isn’t compatible with the HP 8971 family because of it’s incomplete GPIB commands. - In order to extend its possibilities over 2 GHz the only way is to use an outside broadband mixer. And measures can only be done in DSB.
- Only the HP 8970bis compatible with the HP 8971 NF test set extension. And either SSB and DSB measures can be done. - The HP 8350b sweep (version b) is mandatory.
2- Choice of Nf test-set type:-HP 8971bup to 18 GHz-HP 8971cup to 26.5 GHz
HP 8971b 2-18 GHz NF test-set release 23F5DQK November 2010 part 4/4
Abstract
1- Analyser + test-set + sweep hardware
4- What’s DSB and USB mode ?
3- SSB only mode from 1.6 to 2.4 GHz, why ? ?
Abstract
2- GPIB commands
5- Unstable gain/Nf zeroiing in USB mode after calibrating & cure
6- DSB and SSB comparaison measurements on 2 amps
7- Conclusion
HP 8971b 2-18 GHz NF test-set release 24F5DQK November 2010 part 4/4
1- Whole configuration hardware
HP 8971b 2-18 GHz NF test-set release 25F5DQK November 2010 part 4/4
HP 8971b NF extension set
RF in10 MHz -18 GHz
IF out
LO in
HP 8350b sweep
HP 8970b NF analyser
HP 8971b NF test set
HPIB cables
HP 8971b 2-18 GHz NF test-set release 26F5DQK November 2010 part 4/4
- Model b goes up to 18 GHz and c, up to 26 GHz- 2 HPIB cables needed between analyser, extention and sweep
Agilent HP 8971b (or c model) noise figure test-set
RF input IF outputLO input
Measuring mode indicators (here SSB1)
Operation Modes:- Band 1 - SSB1 (10-1600 MHz) using HP 8970b internal mode- Band 2 - SSB2 (1601-2400 MHz, 700 MHz IF) mandatory !- Band 3 - SSB3 (2401-18000 MHz, 450 MHz IF)- Band 4 - DSB (2401-18000 MHZ, 10 MHz IF)
It’s principally constitued by:- a YIG following filter with HPIB tracking software- an RF front-end broadband preamp (optional)- a broadband mixer
HP 8971b NF extension set
choice of both possibilities
HP 8971b 2-18 GHz NF test-set release 27F5DQK November 2010 part 4/4
2- GPIB (or HPIB) commands
HP 8971b 2-18 GHz NF test-set release 28F5DQK November 2010 part 4/4
GPIB commands
GPIB command addresses
HP 8970b gain/Nf analysermasterdefault address 18
HPIB cableHP 8971b NF test-setslave sweepdefault address 19
HPIB cable
HP 8350b sweepslave sweepdefault address 8
HP 8971b 2-18 GHz NF test-set release 29F5DQK November 2010 part 4/4
1,5 SP 10 MHz to 18 GHz, no user LO 40,0 SP 8 HP 8970b address
45,0 SP enables HP 8971b in mode 1.5 to 1.9 40,1 SP 19 Sys LO address
45,1 SP enables HP 8971b in all modes 40,2 SP 10 HP 8971b address
41,0 SP Takes the HP 8350b control 40,4 SP 8 SIB address
41,2 SP Takes the HP 8571b synth control
42,5 SP Power level in dBm
4,1 puis 46,0 SP Enable system LO on SIB
17,0 SP SSB meases 36,0 SP enable HP 8671b fine tuning in cal
17,1 SP DSB meases 36,1 SP disable HP 8671b fine tuning in cal
Start 6000 Enter Start 6 GHz
Stop 12000 Enter Stop 12 GHz
Step size 100 Enter Step size
GPIB command examples
or
or or
GPIB commands
HP 8971b 2-18 GHz NF test-set release 210F5DQK November 2010 part 4/4
3- SSB mode between 1.6 and 2.4 GHz ??
HP 8971b 2-18 GHz NF test-set release 211F5DQK November 2010 part 4/4
SSB mode from 1.601 GHz to 2.401GHz mandatory : why ?
Spectrum around 1.9 GHz, generated by an HP 83522a (also 8.4 GHz HP 83525a) plugin
- The HP 8970 above 1.6 GHz needs a normal broadband mixer feeded with an HP 8350 sweep LO - Normal gain/Nf zeroiing in DSB mode à (1.9 +- 0.3) GHz is totally unstable- @ 1.9 GHz the sweep plugin is generating an image frequency only 35 dBc (under carrier) !
- The only way to solve the problem is to translate the LO frequency 700 MHz up SSB mode
Carrier
Image
Carrier
Image
HP 8971b 2-18 GHz NF test-set release 212F5DQK November 2010 part 4/4
4- DSB or USB mode : why ?
HP 8971b 2-18 GHz NF test-set release 213F5DQK November 2010 part 4/4
DSB and USB mode explanation
Agilent HP 8971b (or c model) noise figure test-set
DSB mode
USB mode
LSB mode
HP 8971b 2-18 GHz NF test-set release 214F5DQK November 2010 part 4/4
Agilent HP 8971b (or c model) noise figure test-set
- With relatively broadband amps, the DSB mode is preferred- In this case the error between DSB and SSB mode is little, because IF signal of equal strengths- No need of additional filter or preamplifier
DSB and USB mode explanation
HP 8971b 2-18 GHz NF test-set release 215F5DQK November 2010 part 4/4
Comparaison between Agilent/HP and Eaton/Maury designs
The choice in the industry
DSB and SSB measures comparaisons, according to Eaton
HP 8971b 2-18 GHz NF test-set release 216F5DQK November 2010 part 4/4
5- Unstable zeroiing in USB mode after calibrating & cure
HP 8971b 2-18 GHz NF test-set release 217F5DQK November 2010 part 4/4
Direct DSB and SSB modes from 2.41 to 18 GHz : great calibration stability differences
Unstable gain/Nf zero in SSB mode after calibrating
- DSB mode : no Yig filter use - - very stable gain/ Nf zeroiing - - no problem - SSB mode : unstable calibration !
-the HP 8971b internal Yig is decreasing the uncorrected NF about 10 to 15 dB down-the dynamical measure range is falling about 15 dB and SSB DUT meases on DUT are quite impossible
Cure : stable broadband amplifier inserting and calibrating again
- 1st try with an LNA 3000a broadband amp « under hand » (Fmax=3 GHz), giving 15 dB gain from 50 MHz to more than 3 GHzUSB zeroiing calibration from 1.61 to 3.5 GHzon bands 2 and 3 immediate stable gain/Nf zero
- 2nd try with a Miteq broadband amp (Fmax= 12 GHz), giving 25 dB stable gain from 50 MHz to more than 3 GHzUSB zeroiing calibration from 1.61 to 12 GHzon bands 2 and 3 immediate stable gain/Nf zero
Putting an additional amp after noise source and before NF test-set input
Then the DUT is inserted between noise source output and add amp input
HP 8971b 2-18 GHz NF test-set release 218F5DQK November 2010 part 4/4
SSB mode measures : adding a broadband stable amplifier gain>10 dB
Miteq 12 GHz broadband amp addition for SSB mode
- Direct calibration in DSB mode : no problem and stable gain/ Nf zeroiing- In SSB mode this case the error between DSB and SSB mode is little, because IF signal of equal strengths- No need of additional filter or preamplifier
Model found : Miteq 45 MHz – 12 GHz 20 dB broadband amplifier
9V<U<=15V, I=120 mA
HP 8971b 2-18 GHz NF test-set release 219F5DQK November 2010 part 4/4
Miteq model AFS2-00010600-25-S6-4 : scalar meases
U>=9V, I=120 mA
10 GHz22 dB
12.8 GHz10 dB
Miteq 12 GHz broadband amp addition for SSB mode
HP 8971b 2-18 GHz NF test-set release 220F5DQK November 2010 part 4/4
6- DSB and USB comparaison measurements on 2 amps
HP 8971b 2-18 GHz NF test-set release 221F5DQK November 2010 part 4/4
Miteq AFS2 00010600
0
5
10
15
20
25
30
0 2000 4000 6000 8000 10000 12000 14000
Frequency (MHz)
Gai
n (
dB
)
1
2
3
4
5
6
7
Nf
(dB
)
Gain DSB (dB)Gain SSB (dB)Nf DSB (dB)Nf SSB (dB)
Miteq model AFS2-00010600-25-S6-4 : gain & NF mesures in DSB & USB modes
U>=9V, I=120 mA
Miteq 12 GHz broadband amp addition for SSB mode
SSB and DSB meases comparaison
Gain 25 dB
Nf 2.1 dB
DSBSSB
HP 8971b 2-18 GHz NF test-set release 222F5DQK November 2010 part 4/4
Miteq 12 GHz broadband amp addition for SSB modeDSB & SSB meases on DB6NT preamp
5
10
15
20
25
30
35
8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000
Frequency (MHz)
Gai
n (d
B)
0,5
1
1,5
2
2,5
3
3,5
Nf (
dB
)
HP 346b Gain DSB (dB)HP 346b Gain SSB (dB)HP 346b Nf DSB (dB)HP 346b Nf SSB (dB)
10.4 GHz
4 dB attenuator as isolator after DUT
HP 8971b 2-18 GHz NF test-set release 223F5DQK November 2010 part 4/4
7- Conclusion
HP 8971b 2-18 GHz NF test-set release 224F5DQK November 2010 part 4/4
Conclusion
- In order getting a same initial stable calibration as on DSB, the SSB mode needs a further 10 to 15 dB broadband amplifier at the Nf test-set input- An additional 3 to 4 dB front-end attenuator between DUT output and broadband amp input gives a little better isolation- DSB and SSB meases are giving roughly same results in the horizontal part of the gain curve- On the side of the gain curve, better precision is achieved in SSB
