lecture 2: vlsi overview - saraju mohantylecture 2: vlsi overview csce 5730 digital cmos vlsi design...
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Lecture 2: VLSI OverviewCSCE 5730
Digital CMOS VLSI DesignInstructor: 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.
CSCE 5730: Digital CMOS VLSI Design 1
y g y
Lecture Outline
• Historical development of computersI t d ti t b i di it l t• Introduction to a basic digital computer
• Five classic components of a computer• Microprocessor• IC design abstraction levelIC design abstraction level• Intel processor family
D l t l t d f IC• 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(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 tinypiece of silicon. It contains thousands, or even millions, ofpiece of silicon. It contains thousands, or even millions, oftransistors, which are interconnected via superfine traces ofaluminum. The transistors work together to store and manipulatedata so that the microprocessor can perform a wide variety ofdata so that the microprocessor can perform a wide variety ofuseful functions. The particular functions a microprocessorperforms are dictated by software. (source : Intel)
• Simply speaking, microprocessor is the CPU on a single chip.CPU stands for “central processing unit” also known asp gprocessor.
P b “ l ” “ i l ” A• Processor can be “general purpose” or “special purpose”. Aspecial purpose processor is also known as “application specificintegrated 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
CSCE 5730: Digital CMOS VLSI Design 12
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 - 1958The First Integrated Circuit – Jack Kilby, Texas Instruments
1 Transistor and 4 Other Devices on 1 Chip1 Transistor and 4 Other Devices on 1 ChipWinner 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 Resistors4 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).
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
CSCE 5730: Digital CMOS VLSI Design 29
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
CSCE 5730: Digital CMOS VLSI Design 30
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
CSCE 5730: Digital CMOS VLSI Design 31
Design Abstraction Levels
SYSTEM
MODULE
+
GATE
MODULE
CIRCUIT
GATE
GDEVICE
n+n+S
GD
CSCE 5730: Digital CMOS VLSI Design 32
Digital Circuits : Logic to Device
(NAND Gate) (IEC Symbol)( Gate) ( C Sy bo )
(Transistor Diagram) (Layout Diagram)
CSCE 5730: Digital CMOS VLSI Design 33
( 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)
CSCE 5730: Digital CMOS VLSI Design 34
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)
CSCE 5730: Digital CMOS VLSI Design 35
Digital IC Fabrication Flow
CSCE 5730: Digital CMOS VLSI Design 36
Technology Growth and Moore's Law
CSCE 5730: Digital CMOS VLSI Design 37
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
CSCE 5730: Digital CMOS VLSI Design 38
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
CSCE 5730: Digital CMOS VLSI Design 39
VLSI Trend
PowerPower,Operatingfrequency andfrequency, andThroughputhavehaveincreased.
1967 2007
VLSI technology is the fastest growing technology in human history.
40
1967 2007
CSCE 5730: Digital CMOS VLSI Design
Technology Scaling Trend
Source: Bendhia 2003
CSCE 5730: Digital CMOS VLSI Design 41
Evolution in Complexity
CSCE 5730: Digital CMOS VLSI Design 42
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
CSCE 5730: Digital CMOS VLSI Design 43
Increase in Transistor Count
Pentium IV (55 Million transistors)
Transistors on Lead Microprocessors double every 2 years
CSCE 5730: Digital CMOS VLSI Design 44
Die Size Growth
100m
m)
8080 8086286
386486 Pentium ® procP6
10
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
CSCE 5730: Digital CMOS VLSI Design 45
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
CSCE 5730: Digital CMOS VLSI Design 46
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
CSCE 5730: Digital CMOS VLSI Design 47
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
CSCE 5730: Digital CMOS VLSI Design 48
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!
CSCE 5730: Digital CMOS VLSI Design 49
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 productivityC t ITRS R d
CSCE 5730: Digital CMOS VLSI Design 50
Courtesy, ITRS Roadmap
VLSI Trend : CPUVLSI Trend : CPU• Core 2 Duo has 291M transistors (2006).• Core 2 Duo T5000/T7000 series mobile
processors, called Penryn uses 800M of( )45 nanometer devices (2007).
Core 2 Quad: (2006)Source: http://www gearfuse com/
CSCE 5730: Digital CMOS VLSI Design 51
Source: http://www.gearfuse.com/
VLSI Trend : GPU
GeForce 6800
Source: GPU Gems 2
CSCE 5730: Digital CMOS VLSI Design52
Source: GPU Gems 2
VLSI Trend : Salient Points
• Increased Complexity: 340 Billion transistorsIncreased Complexity: 340 Billion transistorsmanufactured in 2006.
(World population 6.5 Billion!)• High Power Dissipation: Power dissipation per transistor
has reduced, but power dissipation of overall chipincreasingincreasing.
• Increased Parallelism with Multicore Architecture: Toarchive highest performance multiples have been putarchive highest performance multiples have been puttogether in the same die.
• Smaller Process Technology: Use of smaller nanoscaleCMOS technology, 32nm node and high- CMOS.
• Reduced Time-to-market: For competitiveness and profit.
CSCE 5730: Digital CMOS VLSI Design53
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
CSCE 5730: Digital CMOS VLSI Design 55
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
CSCE 5730: Digital CMOS VLSI Design 57
Die Cost
Single die
Wafer
G i t 12” (30 )Going up to 12” (30cm)
CSCE 5730: Digital CMOS VLSI Design 58
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
CSCE 5730: Digital CMOS VLSI Design 59
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
CSCE 5730: Digital CMOS VLSI Design 60
Defects
area dieareaunit per defects1yield die
is approximately 3
44area)(diecost die f
NOTE: Solve Example 1.3 , page-18 of Rabaey text book.
CSCE 5730: Digital CMOS VLSI Design 61
p , p g y
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
CSCE 5730: Digital CMOS VLSI Design 62
Reliability―Noise in Digital Integrated CircuitsNoise in Digital Integrated Circuits
v(t) VDD
i(t)v(t) VDD
Inductive coupling Capacitive coupling Power and groundnoise
CSCE 5730: Digital CMOS VLSI Design 63
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
CSCE 5730: Digital CMOS VLSI Design 64
Definition of Noise Marginsg
"1"
VNoise margin high
VIHUndefined
VOH NMH
Noise margin lowVIL
UndefinedRegion
VONML g
"0"
VOL
Gate Output Gate Input
CSCE 5730: Digital CMOS VLSI Design 65
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
CSCE 5730: Digital CMOS VLSI Design 66
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;
CSCE 5730: Digital CMOS VLSI Design 67
Fan-in and Fan-out
MN
M
Fan-out N Fan-in M
CSCE 5730: Digital CMOS VLSI Design 68
The Ideal Gate
V out
Ri = Ro = 0o Fanout = NMH = NML = VDD/2g = NMH NML VDD/2
V in
CSCE 5730: Digital CMOS VLSI Design 69
Delay Definitions
Vin
50%
t t
t
Vout
tpHL tpLH
90%90%
50%
tf trt10%
CSCE 5730: Digital CMOS VLSI Design 70
A First-Order RC Network
voutR
vin C
tp = ln (2) t = 0.69 RC
Important model – matches delay of inverter
CSCE 5730: Digital CMOS VLSI Design 71
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
CSCE 5730: Digital CMOS VLSI Design 72
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
CSCE 5730: Digital CMOS VLSI Design 73
Summary
• Digital integrated circuits have come a long way andg g g ystill have quite some potential left for the comingdecadesS i t ti h ll h d• Some interesting challenges ahead– Getting a clear perspective on the challenges and potential
solutions is the purpose of this bookp p• Understanding the design metrics that govern digital
design is crucialC t li bilit d d di i ti– Cost, reliability, speed, power and energy dissipation
CSCE 5730: Digital CMOS VLSI Design 74