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Transcript of Ppt of Principles of Cmos Vlsi Design
EE559 MOS VLSI Design
Prepared by CK & KR 1
EE559: MOS VLSI Design
I t t K RInstructors: K. RoyEmail: [email protected]: www.ece.purdue.edu/~kaushikOffice: MSEE 232Telephone: 494-2361Office Hours: Tuesday/Thursday 11am-12noon
b i t tor by appointments
Grading Policy
• Mid-terms + quizzes + hw will account for 75% of the grade– 3 mid-terms– Mandatory and has to be taken on the scheduled day of the exam.
• Project will account for 25% of the grade. Late projects will not be accepted.
• You are guaranteed an A if your weighted average score over exams, quizzes, and projects is 90 or above.
• Any form of cheating will be heavily penalized and reported to the Dean of students and may result in a failing grade.y g g
• Instructor reserves right to change project requirements.
EE559 MOS VLSI Design
Prepared by CK & KR 2
Text and References
• Text:Text:– Digital Integrated Circuits: A Design Perspective,
J. Rabaey, Prentice Hall, Second edition
• References:– Principles of CMOS VLSI Design: A Systems Perspective,
2nd Ed., N. H. E. Weste and K. Eshraghian, Addison Wesley
– Circuits, Interconnects, and Packaging for VLSI, H. Bakoglu, Addison Wesley
• Class Notes:– http://www.ece.purdue.edu/~vlsi/ee559/20001
Conferences & Journals
• IEEE Transactions on VLSI Systems• IEEE Transactions on CAD of IC’sIEEE Transactions on CAD of IC s• IEEE Journal of Solid State Circuits• IEEE VLSI Circuits Symposium• Journal of Electronic Testing• ACM Design Automation Conference• IEEE International Conference on CAD• IEEE Solid State Circuits Conference• International symposium on Low-Power Electronics & Design• IEEE Conference on Computer Design• IEEE International Test Conference
EE559 MOS VLSI Design
Prepared by CK & KR 3
Course Outline
• Introduction: Historical perspective and Future Trend• Semiconductor Devices
CMOS Logic Layout techniques• CMOS Logic, Layout techniques• MOS devices, SPICE models• Inverters: transfer characteristics, static and dynamic
behavior, power and energy consumption of static MOS inverters
• Designing combinational logic gates in CMOS– Static CMOS design: Complementary CMOS, ratioed logic,
pass-transistor logic– Dynamic CMOS logic
Course Outline (Cont’d)
• Designing combinational logic gates (Cont’d)– Power consumption in CMOS gatesp g– Low-power design
• Designing sequential circuits• Interconnect and timing issues• Designing memory and array structures• Designing arithmetic building blocks
S f• VLSI testing and verification
EE559 MOS VLSI Design
Prepared by CK & KR 4
VLSI CAD Lab and TA
• VLSI CAD Lab located in 360 Potter Engineering Center– SUN workstations running Mentor Graphics tools– Courtesy key for after-hour access can be obtained from
front desk in Potter Engineering Library– Additional workstations in MSEE 186
• Lab TA: Kuntal Roy ([email protected])– Facilitates the use of lab design tools. – Office hours: TBA– Lab Orientation will be held in the second week
• Lab URL– http://min.ecn.purdue.edu/~mgcdevel/ee559_lab.html
Course Project
• Complete design of a functional logic block or system– Complexity of 1000+ transistors or novelty– Design using the CADENCE tools and HSPICE
• Design your own library from scratch– Functionality to be verified– Critical path timing should be verified using HSPICE– Project report due the last day of class– Project presentation by each group in the last week of class– Work in a group of 2 will be allowed in special cases– Start early!Start early!– Emphasis on new ideas, power dissipation, performance,
reconfigurability, low voltage design
EE559 MOS VLSI Design
Prepared by CK & KR 5
Introduction:A Historical Perspective and Future
Trends
References: Adapted from: Digital Integrated Circuits: A Design Perspective, p g g g p ,
J. Rabaey © UCBPrinciples of CMOS VLSI Design: A Systems Perspective,
2nd Ed., N. H. E. Weste and K. Eshraghian
Digital Computation: Particle Location is an Indicator of State
1 1 0 0 1 0
EE559 MOS VLSI Design
Prepared by CK & KR 6
Physical Medium for Computation: Barrier Model
V=0 SOURCE DRAIN
GATE
Eb
V=Vmin=Ebmin
ToxLeff
Vg
Vd
1. Can we operate with Vmin ~ KBTln2 ?
2. Can we operate with Qmin = q ?
EE559 MOS VLSI Design
Prepared by CK & KR 7
The First Computer
• The Babbage Differential gEngine (1834)
• 25,000 mechanical parts• Cost £17,470
Digital Electronic Computing
• Started with the introduction of vacuum tube• ENIAC for computing artillery firing tables in 1946• ENIAC for computing artillery firing tables in 1946• Integration density
– 80 feet long, 8.5 feet high, and several feet wide– 18,000 vacuum tubes
• Reliability issues and excessive power consumption• Did not go far until the invention of the transistor at
Bell Lab in 1947
EE559 MOS VLSI Design
Prepared by CK & KR 8
HISTORY• MOS field-effect transistor: Lilienfeld (1925), Heil (1935)
• Bipolar transistors: Bardeen (1947), Schockley (1949)
• First Bipolar digital logic: Harris (1956)First Bipolar digital logic: Harris (1956)– IC Logic family:
• Transistor-Transistor Logic (TTL) (1962)
• Emitter-Coupled Logic (ECL) (1971)
• Integrated Injection Logic (I2L) (1972)
• PMOS and NMOS transistors on the same substrate: Weimer (1962), Wanlass (1965)( ), ( )
• PMOS-only logic until 1971 when NMOS technology emerged• NMOS-only logic until late 1970s, when CMOS technology took
over• Later developments: BiCMOS, GaAs, low-temperator CMOS,
super-conducting technologies, Nano-electronic
Exponential Increase in Leakage
Non-SiliconSilicon Silicon
1 µm 100 nm 10 nm
1970 1980 2000 2010 2020
5 µm
Non Silicon Technology
Silicon Micro- electronics
Silicon Nano- electronics
GateS
Subthreshold Leakage
Gate Leakage
% o
f Tot
al)
40%
50%Must stop
at 50%
610ON
OFF
II
=310ON
OFF
II
= 2~6~ 10ON
OFF
II
Junctionleakage
Source
n+n+
Bulk
Drain
A. Grove, IEDM 2002
Technology (μ)
Leak
age
Pow
er (%
0%
10%
20%
30%
1.5 0.7 0.35 0.18 0.09 0.05
EE559 MOS VLSI Design
Prepared by CK & KR 9
Technology Trend
Buried Oxide (BOX)Substrate
Fully-depleted body
Gate
VG
VS VD
DrainSource
Vback
Buried Oxide (BOX)Substrate
Fully-depleted body
Gate
VG
VS VD
DrainSource
Vback
Bulk-CMOS
FD/SOI
Nano devices Carbon nanotubeIII-V devices nano-wiresSpintronics
DGMOS
FinFET TrigateBuried Oxide (BOX)
Substrate
Source Floating Body Drain
GateVS
VG
VD
Buried Oxide (BOX)
Substrate
Source Floating Body Drain
GateVS
VG
VD
PD/SOISingle gate device Multi-gate devicesPD/SOI
Design methods to exploit the advantages of technology innovations
Things NaturalThings Natural Things ManmadeThings ManmadeHead of a pin
1-2 mm
Ant~ 5 mm
Dust mite
200 μm
The Challenge
0 1 mm
1 millimeter (mm)
1 cm10 mm
10-2 m
10-3 m
10 4
Micro
wave
1,000,000 nanometers =
The Scale of Things The Scale of Things –– Nanometers and MoreNanometers and More
MicroElectroMechanical (MEMS) devices10 -100 μm wide
Fly ash~ 10-20 μmHuman hair
~ 60-120 μm wide
Red blood cellswith white cell
~ 2-5 μm
200 μm
O O
O
OO
O OO O OO OO
O
S
O
S
O
S
O
S
O
S
O
S
O
S
O
S
PO
O
Fabricate and combine nanoscale building blocks to make useful devices, e.g., a photosynthetic reaction center with
Mic
row
orld
0.1 μm100 nm
1 micrometer (μm)
0.01 mm10 μm
0.1 mm100 μm
10-4 m
10-5 m
10-6 m
10-7 m
Visib
le
1,000 nanometers =
Infra
red
Zone plate x-ray “lens”Outer ring spacing ~35 nm
Red blood cellsPollen grain
Smaller is different!
DNA~2-1/2 nm diameter Atoms of silicon
spacing ~tenths of nm
Quantum corral of 48 iron atoms on copper surfacepositioned one at a time with an STM tip
Corral diameter 14 nm
ATP synthase
~10 nm diameterNanotube electrode
Carbon nanotube~1.3 nm diameter
integral semiconductor storage.
0.1 nm
1 nanometer (nm)
0.01 μm10 nm
10-8 m
10-9 m
10-10 m
Nan
owor
ld Ultra
violet
Soft
x-ray
Office of Basic Energy SciencesOffice of Science, U.S. DOE
Version 10-07-03, pmd
Carbon buckyball
~1 nm diameter
Self-assembled,Nature-inspired structureMany 10s of nm
More is different!
EE559 MOS VLSI Design
Prepared by CK & KR 10
Variation in Process ParametersDevice 1 Device 2
130nm
30 %
1.11.1
1 .21 .2
1 .31 .3
1 .41 .4
rmal
ized
Fre
quen
cyrm
aliz
ed F
requ
ency
Source: Intel
Channel length
5X0.90 .9
1 .01 .0
11 22 33 44 55N o rm alized L eakag e (N o rm a lized L eakage ( IsbIsb ))
NorNor
Delay and Leakage Spread
100
1000
10000
nt a
tom
s Source: Intel
Inter and Intra-die Variations
Device parameters are no longer deterministic
10
100
1000 500 250 130 65 32Technology Node (nm)
# do
paRandom dopant fluctuation
ReliabilityTemporal degradation of performance -- NBTI
y
Tech. generation
Failu
re p
roba
bilit
y
TimeLif tiDefects Life time degradationInterface trap generation over time
EE559 MOS VLSI Design
Prepared by CK & KR 11
Scaling & Ion/Ioff
1 um 100 nm 10 nm
• Increasing leakage
• Increasing process variations
Non-Silicon technology
Silicon micro electronics
I
V• Carbon Nanotubes
Silicon nano electronics
610=OFF
ON
II 310=
OFF
ON
II
p
• Short Channel Effects
• Molecular transistors
• Molecular RTDs
410=OFF
ON
II
2. Power & Power Density
atts
)
P6Pentium ® proc
10
100
cm2 )
Pow
er (W
a 486
3862868086
80858080
80084004
0.1
1
Pow
er D
ensi
ty (W
/
Year1971 1974 1978 1985 1992 2000
Year
Increased Average Power• Battery Life • Cooling Cost
Increased Power Density• Reliability
Source: Intel
EE559 MOS VLSI Design
Prepared by CK & KR 12
Nano-Scaled Si DevicesSi Fin
DGMOSPlanar double-gate structure
FinFET or Tri-GateQuasi-planar DG structure
Ground PlaneSOI MOSShared back gate DG devices
Independent gate FinFET Bulk Si MOSFETs
Variation in Process Parameters
1 3 0 n m
3 0 %
1 .11 .1
1 .21 .2
1 .31 .3
1 .41 .4
qy
ency
(nor
m)
S I t l
1000
10000
oms Source: Intel
5 X0 .90 .9
1 .01 .0
11 22 33 44 55Leakage (normalized)
Freq
ue Source: Intel
Inter and Intra-die Variations
10
100
1000 500 250 130 65 32Technology Node (nm)
# do
pant
ato
Random dopant fluctuation
EE559 MOS VLSI Design
Prepared by CK & KR 13
Evolution in Complexity
Processor Trends
PP 66 PPro-150UltraSparc-167
HP PA8000
700
800
i486C-33486-66
PP-66
DX4 100
PPC 601-80MIPS R4400
PP-133
PPro 150
PPro200
MIPS R10000A21164-300SuperSparc2-90
HP PA7200
PPC 604-120A21064APP-100
300
400
500
600
Die
Siz
e (m
il2)
i386i386C-33
0
100
200
300
'91 '93 '94 '95 '96
EE559 MOS VLSI Design
Prepared by CK & KR 14
Processor Trends (cont’d)
A21064A
A21164-300300
PP-100
MIPS R4400
SuperSparc2-90
PPC 604-120
PPro-150
PPC603e-100
PP166MIPS R10000
PPro200
PP-66486-66 PPC 601-80
HP PA7200PP-133
UltraSparc-167HP PA8000
MIPS R5000
DX4 100100
150
200
250
Freq
(MH
z)
i386i486C-33
i386C-33PP-66
0
50
'91 '93 '94 '95 '96
Higher Performance:•Higher Frequencies (2x/Generation)•Higher Device counts (2x /Generation)
Power Trends
A21164-300 HP PA8000
35
40
PP-66
A21064A
MIPS R4400
SuperSparc2-90PPC 604-120
PPro-150
PP166MIPS R5000
MIPS R10000
PPro200UltraSparc-167
HP PA7200
15
20
25
30
35
Pow
er(W
)
[Source: Microprocessor Report]
486-66DX4 100
PP-100MIPS R4400
PP-133
PPC603e-100
PP166PPC 601-80
i386C-33i486C-33
i3860
5
10
'91 '93 '94 '95'94 '96
2x Performance Increase ==> 2x power increase
EE559 MOS VLSI Design
Prepared by CK & KR 15
• Chips fail when they get hot• Need compact and cost-effective cooling solns
Heat Dissipation
p g
CPU Thermal Soln Cost
486/33mhz HeatSink $0.50486DX2 66mhz Heatsink $1.00Pentium 66mhz Larger Heatsink $2.00
System Fan $4.00
• Cooling Solns will become more exotic/expensive– Extruded Heatsinks, Heatpipes, Blowers, Noise....
• Every Watt impacts System Cost, esp. for HVM
Where is the Power Going? (Mobile PC)
20
25
30
CPU Power: predicted from average device count/area growth
0
5
10
15
89 91 92 93 94 95 96 97
CPU Graphics I/O Subsystem Total
• CPU Power increasing (Predicted in 1994 Low power workshop)
• Graphics & Chipset Power increasing faster than predicted
p g g
Power reduction is not only a CPU problem
EE559 MOS VLSI Design
Prepared by CK & KR 16
Intel 4004 Microprocessor
Intel Pentium (II) Microprocessor
EE559 MOS VLSI Design
Prepared by CK & KR 17
Dunnington is the first IA (Intel Architecture) processor with 6-cores, is based on the 45nm high-k process technology, and has large shared caches.
Tukwila, 4-cores, world's first 2 billion transistor microprocessor
EE559 MOS VLSI Design
Prepared by CK & KR 18
T h l ( ) 0 25 0 18 0 13 0 10 0 07
National Technology Roadmap for Semiconductor (NTRS)
Technology (um) 0.25 0.18 0.13 0.10 0.07Year 1998 2001 2004 2007 2010
# transistors 28M 64M 150M 350M 800MOn-Chip Clock (MHz) 450 600 800 1000 1100
Area (mm2) 300 360 430 520 620Wiring Levels 5 5-6 6 6-7 7-8
Interconnect Performance Trend
Technology (um) 0.25 0.18 0.15 0.13 0.10 0.072cm line delay (ns) 2.589 2.480 2.650 2.620 3.730 4.670
1mm line delay (ns) 0.059 0.049 0.051 0.044 0.052 0.042
Intrinsic gate delay (ns) 0.071 0.051 0.049 0.045 0.039 0.022
EE559 MOS VLSI Design
Prepared by CK & KR 19
Interconnect Complexity
Technology (um) 0.25 0.18 0.13 0.10 0.07Length (m) 820 1,480 2,840 5,140 10,000
6 6 8 8 9Wiring Levels 6 6-7 7 7-8 8-9Opt. # buffers per net few many
Opt. # wiresizes per net few manyOpt. # buffers per chip 5K 25K 54K 230K 797K
• Performance
• Signal reliability
• Electromigration
Distributions of Wire lengths
1E+06
1E+07
ts
Rent's exponent = 0.6Rent's coefficient = 4.0
1E+01
1E+02
1E+03
1E+04
1E+05
umbe
r of
Inte
rcon
nect
0.07 um tech.
Rent s coefficient 4.0Avg. fanout = 3
1E+00
1E+01
0 10 20 30Length (mm)
Nu
0.25 um tech.
EE559 MOS VLSI Design
Prepared by CK & KR 20
Technology Scaling
Technology scaling improves:
Transistor & interconnect performanceTransistor densityEnergy consumed per switching transition
0.7X scaling factor (30% scaling) results in:
30% t d l d ti (43% f ↑ )30% gate delay reduction (43% freq. ↑ ) 2X transistor density increase (49% area ↓ )Energy per transition reduction
Technology Scaling
• Speed & PerformanceHigh drive current and low parasitics– High drive current and low parasitics
– Low gate delay and high frequency
• Density & Area– Small feature size
• Power & Reliability– Low power supply voltage
L ff t t l k– Low off-state leakage
EE559 MOS VLSI Design
Prepared by CK & KR 21
Technology Generation Scaling
,,7.0 ββ ⎯⎯ →⎯⎯⎯ →⎯⎯⎯→⎯ scalest
scalesdd
scale VVDimensions
reduction)delay (30% 7.07.0
7.07.0 )(
ββ
ββ
=×
⎯⎯ →⎯=
=×⎯⎯ →⎯−=
scalesdd
scalestdd
ICV
D
VVTkWI
ox
22 7.0 β⎯⎯ →⎯= scalesddCVE
IC Frequency & Power Trends
• Clock frequency improves 50%
• Gate delay Hz)100
1000
800
1000
)
PowerPentium
Pentium IIProcessor
R
R
1000
100W)
1000
800improves ~30% • Power increases
50%• Power =
CL V2 f
Freq
uenc
y (M
H
0.1
1
10
Chi
p Po
wer
(W)
200
400
600
requ
ency
(M H
z)
Frequency
486DX CPU
Pentium Processor
386
R100
10
1
0.1Chi
p Po
wer
(W 800
600
400
200
58
1.0 0.8 0.6 .35 .25 .18
Technology Generation (μm)
0.01 1 2 3 4 5 6 7 0
Fr0.01 0
Active switched capacitance “CL” is increasing.
EE559 MOS VLSI Design
Prepared by CK & KR 22
Constant Voltage vs Field Scaling
• Recently: constant e-field scaling, aka voltage scaling 4
5VCC
5voltage scaling
• VCC ⌫ 1V
• VCC & modest VT
scaling• Loss in gate overdrive
(VCC-VT)
0
1
2
3
4
VC
C o
r VT (V
)
VT=.45V
VCC=1.8V
VT
(VCC- VT)Gate over drive
V CC o
r V T
(V) 4
3
2
1
59
1.4 1.0 0.8 0.6 .35 .25 .18Technology Generation (μm)
0 0 1 2 3 4 5 6 70
Voltage scaling is good for controlling IC’s active power, but it requires aggressive VT scaling for high performance
Barriers to Voltage Scaling
Voltage Scaling = Constant Electric Field Scaling
Voltage scaling is good for IC’s active power, but degrades gate over
Leakage powerShort-channel effectsSpecial circuit functionality, noise
drive. Requires VT scaling.
60
Soft errorParameter variation
EE559 MOS VLSI Design
Prepared by CK & KR 23
Barriers to Voltage Scalingka
ge 1000 constrained Ioffmaintain Vcc/Vt
Leakage powerbt
hres
hold
Lea
k
10
100
maintain Vcc/VtShort-channel effectsSoft errorSpecial circuit functionality
61
Technology Generation
Su 10.25um 0.18um 0.13um 0.09um
functionality
Delay
D
DDLd I
VC=τ
2)1()2
(DD
TDDox
Ld
VVVC
LW
C
−=
μτ Long Channel MOSFET
2WW
1 .τ =
−+
CL Tox
VVT
V n p
05 05
0 3 0 9 13
2. .
. ( ) .( ) [1]
D
)1(DD
TSATox
Ld
VVWC
C
−=
υτ Short Channel MOSFET
62
VDD VDDn p0 9( . )
[1] C. Hu, “Low Power Design Methodologies,” Kluwer Academic Publishers, p. 25.
Performance significantly degrades when VDD approaches 3VT.
EE559 MOS VLSI Design
Prepared by CK & KR 24
VT Scaling: VT and IOFF Trade-off
Performance vs Leakage:
VT ↓ IOFF ↑ ID(SAT) ↑ Low VT
ID(SAT)
High VTI DS
IOFFL
IOFFH
VD = VDDfixed Tox2
2 )()( TGSeff
effD VVK
LW
SATI −∝
)(1
TGS VV
eff
effsubthOFF eK
LW
II −∝∝
63
As VT decreases, sub-threshold leakage increasesLeakage is a barrier to voltage scaling
VGVTL VTH)()( 3 TGSSAToxeffD VVCWKSATI −∝ υ
IOFF vs VT
1E-04
IOFF
Log IOFF
1E-09
1E-08
1E-07
1E-06
1E-05IOFF
(A)
)( TGS VVOFF eI −∝
VTP (V)IOFF is an exponential function of VT.
1E-10-0.5 -0.45 -0.4 -0.35 -0.3 -0.25 -0.2
VT (V) - Normalized
EE559 MOS VLSI Design
Prepared by CK & KR 25
Future: Projected Leakage Trends
1,000
10,0000.10 um0.13 um0.18 um0 25 um
1
10
100
IOFF
(nA
/ μm
) 0.25 um
IOFF (0.25um) = 1 nA/um (scales 5X)VT (0.25um) = 450 mV (scales by 15%)
St (30C) = 80 mV/decSt (100C) = 100d VT/dT = 0.7 mV/C
1
30 40 50 60 70 80 90 100 110Temperature (C)
Why Excessive leakage an Issue?
• Leakage component to active power becomes significant % of total power
100
10
1 1.E+00
1.E+01
1.E+02
Active Power
P ti
Pentium Pro Processor
R
R
101
101
100)significant % of total power• Approaching ~10% in 0.18
μm technology• Acceptable limit less than
~10%, implies serious challenge in VT scaling!
1
10-1
10-2
10-3
10-4
10-5
10-6
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
Standby power (component Transistor
Leakage T=110C)
486DX CPU
Pentium Processor386
R100
10-1
10-2
10-3
10-4
10-5
6
Pow
er
(W)
67
1.0 0.8 0.6 .35 .25 .1810
1.E-060 1 2 3 4 5 6 7
Technology Generation (μm)
10-6
Barrier high static leakage (standby) power
EE559 MOS VLSI Design
Prepared by CK & KR 26
Power Trends
• Enable development of ultra low voltage circuits• At lower Vt,
– leakage becomes a problem
Vt Variation for optimum energy2.5
g p– Signal integrity and
Noise margin
• Multiple on-chip Vt 0.5
1
1.5
2
Nor
mal
ized
Ene
rgy
Decreasing Switching Power
Decreasing Leakage Power
Vdd =1.7V
f=20MHz
Vdd = 0..9V
Vdd = 0..5V
• Multiple on-chip Vt, dynamic Vt
• Other challenges for low voltages ?
0.50 0.2 0.4 0.6 0.8 1
Threshold Voltage (Vt)[Source: A.Chandrakasan et.al. Proc of IEEE April’95]
Trends in Microelectronics
• Improvement in device technology– Smaller circuits– Faster circuitsFaster circuits– More circuits on a chip
• Higher Integration– More complex systems– Lower cost of computation– Higher reliability
• Limitations• Limitations– Intrinsic device scaling limits– Cost of fabrication– Interconnect limitation– Large scale design management
EE559 MOS VLSI Design
Prepared by CK & KR 27
Problems of Microelectronics• Design Cost:
– design time– fabrication time
i ibilit t i– impossibility to repair– reduce design cost to be competitive in price
• Marketing Issues:– use most recent technologies to stay competitive in
performance– volume production is inexpensive– time-to-market is critical– time-to-market is critical– evolving market
• Solution:– Hierarchical and abstraction– Different design styles– Computer-Aided-Design
Circuit and System RepresentationsComplex digital system Component gates
+Memory systems
• 3 design domains– Behavioral
• specifies what a particular system does– Structural
• how entities are connected together to effect the prescribed manner
Memory systems
manner– Physical
• how to actually build a structure that has the required connectivity to implement the prescribed behavior
EE559 MOS VLSI Design
Prepared by CK & KR 28
Design Abstraction Levels
SYSTEM
+
CIRCUIT
GATE
MODULE
n+n+S
GD
DEVICE
CIRCUIT
For a Digital Design
• ArchitectureArchitecture• Algorithm• Module or Functional Block• logical• Switch• Circuit• Layout
EE559 MOS VLSI Design
Prepared by CK & KR 29
Behavioral Representation Domain
• Hardware description languageVHDL V il– VHDL, Verilog
• Boolean equation• Within this domain, there are various level of
abstraction– Algorithm– Register transfer level (communication between registers)
Acc Acc + R1
CO = A.B + A.C + B.C
carry
– Boolean equations
Behavioral Representation Domain - cont.
• Algorithm level (Verilog)
output coinput a, b, c
MODULE carry (co, a,b,c)
can include speed info assign co = (a&b)|(a&c)|(b&c);
ENDMODULE
EE559 MOS VLSI Design
Prepared by CK & KR 30
Structural Domain• The levels of abstraction include
– module– gate
input a, b, c;output co;
MODULE carry (co, a, b, c)
wire x, y, z
– switch– circuit
, y,AND g1 (x, a, b)AND g2 (y, a, c)AND g3 (z, b, c)OR g4 (co, x, y, z);
ENDMODULE
Structural Domain- cont.
bab
ac
x bc
z
y xy
co
g3g1
zg4g2
z
EE559 MOS VLSI Design
Prepared by CK & KR 31
Transistor Level
input a, b, c;MODULE carry (co, a, b, c)
output co;wire i1, i2, i3, i4, cn;
NMOS n1(i1, vss, a)NMOS n2(i1, vss, b)
PMOS p1(i3, vdd, b);
...
ENDMODULE
p ( , , );PMOS p2(cn, i3, a);
..
.
Physical Representation
Input a, b, c;MODULE carry ;
p , , ;output co;boundary [0, 0, 100, 400]
port a aluminum width = 1 origin = [0,2]port b aluminum width = 1 origin = [0,7]
.
.port
.
ENDMODULE
Port ci polysilicon ……..
EE559 MOS VLSI Design
Prepared by CK & KR 32
CMOS Logica a
b
s s
b
Consider them as switches
s = 0
a
b
s = 0
a b s = 0
a
b
a b
NMOS transistor PMOS transistorb
s = 1
a
b
as = 1
a
b
s = 1a b b
Inverter (A)
VDD
BA
- Low power dissipation
EE559 MOS VLSI Design
Prepared by CK & KR 33
NAND (AB)
AA
B
A
BBA+
Out
1 1
1 0
0 1
0
1
A
B
A
B
BA.
NOR (A+B)
A
B
A
B
1 0
0 0
0 1
0
1
A
B
A . B
A + B
EE559 MOS VLSI Design
Prepared by CK & KR 34
A
CBADDCBAF +=++= )).((
DCBAF ).( ++=
Complex Gates
B
C
D
D
A B C
VLSI Design is Inter-Disciplinary
• Breadth of field– Semiconductor physics and technology– Integrated electronics– Systems design– Testing– Computer-Aided Design
• Depth of fieldp– Complexity of fabrication technology– Difficulty of design problems