Lecture 1: VLSI Overview

Digital CMOS VLSI DesignDigital CMOS VLSI Design

Instructor: Saraju P. Mohanty, Ph. D.

NOTE: The figures, text etc included in slides are borrowedfrom various books websites authors pages and otherfrom various books, websites, authors pages, and othersources for academic purpose only. The instructor doesnot claim any originality.

Digital CMOS VLSI Design 1

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Lecture Outline

• Historical development of computersIntroduction to a basic digital computer• Introduction to a basic digital computer

• Five classic components of a computer• Microprocessor• IC design abstraction levelIC design abstraction level• Processor Trend

Developmental trends of ICs• Developmental trends of ICs• Moore’s Law

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Introduction to Digital Circuits

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What is a digital Computer ?

A fast electronic machine that acceptsdigitized input information, processes itg p paccording to a list of internally storedinstruction, and produces the resultingp goutput information.

List of instructions Computer program

Internal storage Memory

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Different Types and Forms of Computer

• Personal Computers (Desktop PCs)• Notebook computers (Laptop computers)• Handheld PCsHandheld PCs• Pocket PCs

W k t ti (SGI HP IBM SUN)• Workstations (SGI, HP, IBM, SUN)• ATM (Embedded systems)• Supercomputers

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Five classic components of a Computer

Computer

Processor

Computer

Memory Devices

Control Input

Datapath Output

(1) Input (2) Output (3) Datapath (4) Controller and (5) Memory(1) Input, (2) Output, (3) Datapath, (4) Controller, and (5) Memory

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What is a microprocessor ?

• A microprocessor is an integrated circuit (IC) built on a tiny piece ofsilicon. It contains thousands, or even millions, of transistors, which aresilicon. It contains thousands, or even millions, of transistors, which areinterconnected via superfine traces of aluminum. The transistors worktogether to store and manipulate data so that the microprocessor canperform a wide variety of useful functions The particular functions aperform a wide variety of useful functions. The particular functions amicroprocessor performs are dictated by software. (source : Intel)

• Simply speaking, microprocessor is the CPU on a single chip. CPU standsfor “central processing unit” also known as processor.

• Processor can be “general purpose” or “special purpose”. A special purposeprocessor is also known as “application specific integrated circuit” (ASIC).

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What is an Integrated Circuit ?

• An integrated circuits is a silicon semiconductorcrystal containing the electronic components forcrystal containing the electronic components fordigital gates.Integrated Circuit is abbreviated as IC• Integrated Circuit is abbreviated as IC.

• The digital gates are interconnected toimplement a Boolean function in a IC .

• The crystal is mounted in a ceramic/plasticmaterial and external connections called “pins”are made available.

• ICs are informally called chips.

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How does a microprocessor look?

(1) ASIC (2) Sun UltraSparc (3) PentiumPro

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Historical Development

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VLSI Technology: Highest Growth in History• 1958: First integrated circuit

– Flip-flop using two transistorsFlip flop using two transistors– Built by Jack Kilby at Texas Instruments

• 20032003– Intel Pentium 4 processor (55 million transistors)– 512 Mbit DRAM (> 0.5 billion transistors)512 Mbit DRAM ( 0.5 billion transistors)

• 53% compound annual growth rate over 45yearsy– No other technology has grown so fast so long

• Driven by miniaturization of transistorsDriven by miniaturization of transistors– Smaller is cheaper, faster, lower in power!– Revolutionary effects on societyy y

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VLSI Industry : Annual Sales• 1018 transistors manufactured in 2003

– 100 million for every human on the planet100 million for every human on the planet• 340 Billion transistors manufactured in 2006.

(World population 6 5 Billion!)(World population 6.5 Billion!)200

Globa

100

150

l Sem

icon(B

illions o

50

nductor Bil

of US

$)

01982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002

Year

lings

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Invention of the Transistor• Invention of transistor is the driving factor of

growth of the VLSI technologygrowth of the VLSI technology• Vacuum tubes ruled in first half of 20th century

Large expensive power hungry unreliableLarge, expensive, power-hungry, unreliable• 1947: first point contact transistor

– John Bardeen and Walter Brattain at Bell Labs– Earned Nobel prize in 1956

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Transistor Types

• Bipolar transistorsn p n or p n p silicon structure– n-p-n or p-n-p silicon structure

– Small current into very thin base layer controls largecurrents between emitter and collectorcurrents between emitter and collector

– Base currents limit integration density• Metal Oxide Semiconductor Field Effect• Metal Oxide Semiconductor Field Effect

Transistors (MOSFET)MOS d MOS MOSFETS– nMOS and pMOS MOSFETS

– Voltage applied to insulated gate controls currentbetween source and drainbetween source and drain

– Low power allows very high integration

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The Babbage Difference Machine in 1832g

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The First Electronic Computer in 1946 (ENIAC)p ( )

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How a Home PC Looks Today??

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First Integrated Circuit - 1958• The First Integrated Circuit – Jack Kilby, Texas Instruments• 1 Transistor and 4 Other Devices on 1 Chip1 Transistor and 4 Other Devices on 1 Chip• Winner of the 2000 Nobel Prize

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First Commercial Planar IC - 1960

• Fairchild -- One Binary Digital (Bit) Memory Device on a Chip4 Transistors and 5 Resistors• 4 Transistors and 5 Resistors

• Start of Small Scale Integration (SSI)!! We are in VLSI!!

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First IC Created with Computer-Aided D i T l 1967Design Tools -- 1967

MOSAIC – FairchildMOSAIC Fairchild

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First 1,024 Bit Memory Chip -- 1970

1970’• 1970’s processesusually had onlynMOS transistors

– Inexpensive, butconsume power whileidlidle.

• 1980s-present: CMOSprocesses for low idleprocesses for low idlepower

Intel Corporation DRAM

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Intel 4004 : 2.3K Transistors (1971)

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Pentium : 3.1M Transistors (1993)

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Pentium II : 7.5M Transistors (1997)

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Pentium III : 28.1M Transistors (1999)

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Pentium IV : 52M Transistors (2001)

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Core 2 Duo: 291M Transistors (2006)

Core 2 Duo T5000/T7000 series mobile processors, calledPenryn uses 800M of 45 nanometer devices (2007)

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Penryn uses 800M of 45 nanometer devices (2007).

Nvidia GT200 Graphics Processing Unit• This GPU contains 1.4 billion transistors.• This uses a 65 nm CMOS fabrication process.p

Source: http://www.gdiamos.net

Source: http://nvidiathepoweroffuture.files.wordpress.com/

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Intel’s Tukwila – 2B Transistors

• Quad core i.e. 4 cores per die.• 30 MB of cache.• 2 billion transistors on the die.• 64-bit Itanium family.• 65nm CMOS technology.• Release in early 2010.

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Release in early 2010.

Circuit Design Flow

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Integrated Circuits Categories There are many different types of ICs as listed below.

IC Categories FunctionsIC Categories FunctionsAnalog ICs Amplifiers

FiltersDigital ICs Boolean Gates

Encoders/DecodersMultiplexers / DemultiplexersFlip-flopsCountersCountersShift Registers

Hybrid ICs Mixed Signal Processorsy gInterface ICs Analog-Digital Converters

Digital-Analog Converters

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Levels of Integration (Chip Complexity)Categorized by the number of gates contained in the chip.

IC Number of Functional ExamplesComplexity Gates Complexity

p

SSI <10 Basic gates Inverters, AND gates, OR gates, NANDgates, NOR gatesg g

MSI 10-100 Basic gates Exclusive OR/NORSub modules Adders subtractors encodersSub-modules Adders, subtractors, encoders,

decoders, multiplexers, demultiplexers, counters, flip-flops

LSI 100-1000s Functional modules Shift registers stacksLSI 100 1000s Functional modules Shift registers, stacksVLSI 1000s-

100,000Major building

blocksMicroprocessors, memories

ULSI >100 000 Complete systems Single chip computers digital signalULSI >100,000 Complete systems Single chip computers, digital signalprocessors

WSI >10,000,000 Distributed systems Microprocessor systems

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Digital Logic Families• Various circuit technology used to implement an IC at

lower level of abstraction.• The circuit technology is referred to as a digital logic family• The circuit technology is referred to as a digital logic family.

RTL - Resistor-transistor Logic obsoleteDTL Diode transistor logic obsoleteDTL - Diode-transistor logic obsoleteTTL - Transistor-transistor logic not much used

ECL - Emitter-coupled logic high-speed ICsECL - Emitter-coupled logic high-speed ICsMOS - Metal-oxide semiconductor high-component densityCMOS - Complementary Metal-oxide widely used, low-power high-C OS Co p e e a y e a o desemiconductor

de y used, o po e gperformance and high-packingdensity IC

BiCMOS Bi l C l t hi h t d hi h dBiCMOS - Bipolar ComplementaryMetal-oxide semiconductor

high current and high-speed

GaAs - Gallium-Arsenide very high speed circuitsy g p

Digital CMOS VLSI Design 33

Design Abstraction Levels

SYSTEM

MODULE

+

GATE

MODULE

CIRCUIT

GATE

GDEVICE

n+n+S

GD

Digital CMOS VLSI Design 34

Digital Circuits : Logic to Device

(NAND Gate) (IEC Symbol)( Gate) ( C Sy bo )

(Transistor Diagram) (Layout Diagram)

Digital CMOS VLSI Design 35

( g ) (Layout Diagram)

Implementation Approaches for Digital ICs

Digital Circuit Implementation Approaches

Custom Semi-custom

Cell-Based Array-Based

St d d C llStandard Cells Macro Cells Pre-diffused Pre-wired(FPGA)Compiled Cells (Gate Arrays)

Digital CMOS VLSI Design 36

Implementation Approaches for Digital ICs• Full-custom: all logic cells are customized. A general purpose

microprocessor is designed this way.• Semi-custom: all of the logic cells are from predesigned cell libraries

(reduces the manufacture lead time of the IC)• Standard-cell based IC uses predesigned logic cells such as ANDStandard cell based IC uses predesigned logic cells such as AND

gates, OR gates, MUXs, FFs,.., etc.• Macrocells (also called megacells) are larger predesigned cells,

h i t ll i tsuch as microcontrollers, even microprocessors, etc.• Gate-Array, Sea-of-Gates or prediffused arrays contains array of

transistors or gates which can be connected by wires to implementg y pthe chip.

• Programmable-Logic-Array (PLA) is an example of fuse-basedFPGA design (NOTE: Fuse based nonvolatile and volatile areFPGA design. (NOTE: Fuse-based, nonvolatile and volatile arethree types of FPGAs)

Digital CMOS VLSI Design 37

Digital IC Fabrication Flow

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Technology Growth and Moore's Law

Digital CMOS VLSI Design 39

Different Attributes of an IC or chipWe will briefly discuss the VLSI technological

growth based on these attributes.g

• Transistor count of a chip

• Operating frequency of a chip

• Power consumption of a chip

• Power density in a chip

• Size of a device used in chip

NOTE: Chip is informal name for IC

Digital CMOS VLSI Design 40

NOTE: Chip is informal name for IC.

Moore’s Law

G• 1965: Gordon Moore plotted transistor oneach chip– Transistor counts have doubled every 26 months

• Many other factors grow exponentially– clock frequencyclock frequency– processor performance

Digital CMOS VLSI Design 41

VLSI Trend

PowerPower,Operatingfrequency andfrequency, andThroughputhavehaveincreased.

1967 2007

VLSI technology is the fastest growing technology in human history.

42

1967 2007

Digital CMOS VLSI Design

Technology Scaling Trend

Source: Bendhia 2003

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Evolution in Complexity

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Why Scaling?

• Technology shrinks by 0.7/generationWi h i i 2 f i• With every generation can integrate 2x more functionsper chip; chip cost does not increase significantly

• Cost of a function decreases by 2x• Cost of a function decreases by 2x• But …

– How to design chips with more and more functions?g p– Design engineering population does not double every two

years…• Hence a need for more efficient design methods• Hence, a need for more efficient design methods

– Exploit different levels of abstraction

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Increase in Transistor Count

Pentium IV (55 Million transistors)

Transistors on Lead Microprocessors double every 2 years

Digital CMOS VLSI Design 46

Die Size Growth

100m

m)

8080 8086 286386

486 Pentium ® procP610

e si

ze (m

40048008

80808085

8086Die ~7% growth per year

~2X growth in 10 years

11970 1980 1990 2000 2010

Year

Die size grows by 14% to satisfy Moore’s Law

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Increase in Operating Frequency

10000D bl

P6

1000

Mhz

)

Doubles every2 years

P6Pentium ® proc

486386286808510

100

quen

cy (

28680868085

80808008

1

10

Freq

800840040.1

1970 1980 1990 2000 2010C t I t lYear

Lead Microprocessors frequency doubles every 2 years

Courtesy, Intel

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Power will be a major problem

5KW18KW

100000

5KW 1.5KW

500W 1000

10000

Wat

ts)

8086286

386486

Pentium® proc

10

100

ower

(W

4004800880808085 386

1

10P

0.11971 1974 1978 1985 1992 2000 2004 2008

YearYear

Power delivery and dissipation will be prohibitive

Digital CMOS VLSI Design 49

Power density

10000) Rocket

1000

(W/c

m2

Nuclear

RocketNozzle

100

Den

sity

Reactor

40048008 8085

8086

286 386486

Pentium® procP610

Pow

er

Hot Plate

8080 286 48611970 1980 1990 2000 2010

YYear

Power density too high to keep junctions at low temp

Digital CMOS VLSI Design 50

Challenges in Digital Design

“Microscopic Problems” “Macroscopic Issues”Microscopic Problems• Ultra-high speed design• Interconnect• Noise, Crosstalk

p• Time-to-Market• Millions of Gates• High-Level Abstractions,

• Reliability, Manufacturability• Power Dissipation• Clock distribution.

• Reuse & IP: Portability• Predictability• etc.

Everything Looks a Little Different…and There’s a Lot of Them!

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Productivity TrendsProductivity Trends

10,000,000 100,000,00010,000(M)

100,000

100,000

1,000,000

1,000,000

10,000,000Logic Tr./ChipTr./Staff Month.

1,000

100

r per

Chi

p

1,000

10,000

ty f -M

o.

xity

1,000

10,000

10,000

100,00058%/Yr. compoundedComplexity growth rate10

1

Tra

nsis

tor

10

100

Prod

uctiv

itTr

ans.

/Sta

ff

Com

plex

10

100

100

1,000xxx

xxx

x21%/Yr. compound

Productivity growth rate

x0.1

0.01

0 001

Logi

c

0 01

0.1

1

P(K

) T

1

2003

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2005

2007

2009

100.001 0.01

S S t hSource: Sematech

Complexity outpaces design productivity

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Courtesy, ITRS Roadmap

Circuit Design Metrics

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Design Metrics

H t l t f f di it l• How to evaluate performance of a digitalcircuit (gate, block, …)?

C t– Cost– Reliability

Scalability– Scalability– Speed (delay, operating frequency)– Power dissipation– Power dissipation– Energy to perform a function

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Cost of Integrated Circuits

• NRE (non-recurrent engineering) costsdesign time and effort mask generation– design time and effort, mask generation

– one-time cost factorR t t• Recurrent costs– silicon processing, packaging, test– proportional to volume– proportional to chip area

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NRE Cost is Increasing

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Die Cost

Single die

Wafer

G i t 12” (30 )Going up to 12” (30cm)

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Cost per Transistor

0 10 111

cost: cost: ¢¢--perper--transistortransistor

Fabrication capital cost per transistor (Moore’s law)

0 0010 001

0.010.01

0.10.1 Fabrication capital cost per transistor (Moore s law)

0.000010.00001

0.00010.0001

0.0010.001

0.00000010.0000001

0.0000010.000001

19821982 19851985 19881988 19911991 19941994 19971997 20002000 20032003 20062006 20092009 20122012

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Die Yield%100

per wafer chipsofnumber Totalper wafer chips good of No.

Ypp

yieldDieper waferDiescostWafer cost Die

yieldDieper waferDies

areadie2

diameterwafer areadie

diameter/2wafer per wafer Dies2

areadie2areadie

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Die Defects

area dieareaunit per defects1yield die

is approximately 3

44area)(diecost die f

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Some Examples (1994)So e a p es ( 99 )Chip Metal

lLine idth

Wafer t

Def./ 2

Area 2

Dies/f

Yield Die tlayers width cost cm2 mm2 wafer cost

386DX 2 0.90 $900 1.0 43 360 71% $4

486 DX2 3 0.80 $1200 1.0 81 181 54% $12

Power PC 601 4 0.80 $1700 1.3 121 115 28% $53

HP PA 7100 3 0.80 $1300 1.0 196 66 27% $73

DEC Alpha 3 0.70 $1500 1.2 234 53 19% $149

Super Sparc 3 0 70 $1700 1 6 256 48 13% $272Super Sparc 3 0.70 $1700 1.6 256 48 13% $272

Pentium 3 0.80 $1500 1.5 296 40 9% $417

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Reliability―Noise in Digital Integrated Circuits

v(t) VDD

i(t)v(t) VDD

Inductive coupling Capacitive coupling Power and groundnoise

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Mapping between analog and digital signalspp g g g g

V

Slope = -1V OH

Vout

V

VOH“ 1”

OHVIH

Undefined

DC Operation:Voltage Transfer

Ch t i tiUndefinedRegion

Characteristic

Slope = -1

V OL“ 0” V

VIL

V IL V IH V in

OL0 VOL

Digital CMOS VLSI Design 63

Definition of Noise Marginsg

"1"

VNoise margin high

VIHUndefined

VOH NMH

Noise margin lowVIL

UndefinedRegion

VONML g

"0"

VOL

Gate Output Gate Input

Digital CMOS VLSI Design 64

Noise Budget

• Allocates gross noise margin to expectedsources of noisesources of noise

• Sources: supply noise, cross talk, interference,offsetoffset

• Differentiate between fixed and proportionalnoise sources

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Key Reliability Properties• Absolute noise margin values are deceptive

– a floating node is more easily disturbed than a node driven by alow impedance (in terms of voltage)

• Noise immunity is the more important metric – thebilit t icapability to suppress noise sources

• Key metrics: Noise transfer functions, Output impedance of thedriver and input impedance of the receiver;driver and input impedance of the receiver;

Digital CMOS VLSI Design 66

Fan-in and Fan-out

MN

M

Fan-out N Fan-in M

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The Ideal Gate

V out

Ri = Ro = 0o Fanout = NMH = NML = VDD/2g = NMH NML VDD/2

V in

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Delay Definitions

Vin

50%

t t

t

Vout

tpHL tpLH

90%90%

50%

tf trt10%

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A First-Order RC Network

voutR

vin C

tp = ln (2) t = 0.69 RC

Important model – matches delay of inverter

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Power Dissipation

Instantaneous power:Instantaneous power: p(t) = v(t)i(t) = Vsupplyi(t)

Peak power: P = V iPpeak = Vsupplyipeak

Average power:Average power:

Tt Ttsupply d

VdP )(1

t t supplysupply

ave dttiT

dttpT

P )(1

Digital CMOS VLSI Design 71

Energy and Energy-Delay

Power-Delay Product (PDP) =

E = Energy per operation = Pav tp

Energy-Delay Product (EDP) =Energy Delay Product (EDP)

quality metric of gate = E tp

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Summary

• Digital integrated circuits have come a long way and stillg g g yhave quite some potential left for the coming decades

• Some interesting challenges ahead– Getting a clear perspective on the challenges and potential

solutions is the purpose of this book• Understanding the design metrics that govern digitalUnderstanding the design metrics that govern digital

design is crucial– Cost, reliability, speed, power and energy dissipation

Digital CMOS VLSI Design 73