Introduction to
VLSI Design
[Adapted from Rabaey’s Digital Integrated Circuits, ©2002, J. Rabaey et al.]
EE414 VLSI Design
What is this course is about?
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Introduction to digital integrated circuits.
» CMOS devices and manufacturing technology.
CMOS inverters and gates. Propagation delay,
noise margins, and power dissipation. Sequential
circuits. Arithmetic, interconnect, and memories.
Programmable logic arrays. Design
methodologies.
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What will you learn?
» Understanding, designing, and optimizing digital
circuits with respect to different quality metrics:
cost, speed, power dissipation, and reliability
EE414 VLSI Design
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Digital Integrated Circuits
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Introduction: Issues in digital design
The CMOS inverter
Combinational logic structures
Sequential logic gates
Design methodologies
Interconnect: R, L and C
Timing
Arithmetic building blocks
Memories and array structures
EE414 VLSI Design
Digital Integrated Circuits
What is meant by VLSI?
lBrief history of evolution
lToday’s Chips
lMoore’s Law
lMachines Making Machines
lVLSI Facts of Life
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EE414 VLSI Design
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What is a VLSI Circuit?
VERY LARGE SCALE
A circuit that has 10k ~
10M transistors on a
single chip
•Still growing as number
of transistors on chip
quadruple every 24
months (Moore’s law!)
INTEGRATED CIRCUIT
Technique where many
circuit components and
the wiring that connects
them are manufactured
simultaneously on a
compact chip (die)
EE414 VLSI Design
Brief History
The First Computer: Babbage Difference Engine (1832)
•Executed basic operations
(add, sub, mult, div) in
arbitrary sequences
•Operated in two-cycle
sequence, “Store”, and “Mill”
(execute)
•Included features like
pipelining to make it faster.
•Complexity: 25,000 parts.
•Cost: £17,470 (in 1834!)
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The Electrical Solution
•More cost effective
•Early systems used relays to make simple logic devices
•Still used today in some train safety systems
•The Vacuum Tube
•Originally used for analog processing
•Later, complete digital computers realized
High Point of Tubes: The ENIAC
•18,000 vacuum tubes
•80 ft long, 8.5 ft high, several feet wide
EE414 VLSI Design
ENIAC - The first electronic computer
(1946)
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Dawn of the Transistor Age
1947: Bardeen and Brattain
create point-contact transistor
w/two PN junctions. Gain = 18
1951: Shockley develops
junction transistor which can
be manufactured in quantity.
EE414 VLSI Design
Early Integration
Jack Kilby, working at Texas Instruments,
invented a monolithic “integrated circuit” in
July 1959.
He had constructed the flip-flop shown in the
patent drawing above.
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Early Integration
In mid 1959, Noyce develops the
first true IC using planar transistors,
back-to-back pn junctions for
isolation, diode-isolated silicon
resistors and SiO2 insulation with
evaporated metal wiring on top
EE414 VLSI Design
Practice Makes Perfect
1961: TI and Fairchild introduce first
logic IC’s (cost ~ $50 in quantity!).
This is a dual flip-flop with 4
transistors.
1963: Densities and yields
improve. This circuit has four
flip-flops.
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Practice Makes Perfect
1967: Fairchild markets the first
semi-custom chip. Transistors
(organized in columns) can be easily
rewired to create different circuits.
Circuit has ~150 logic gates.
1968: Noyce and Moore leave Fairchild to form
Intel. They raise $3M in two days and move to
Santa Clara. By 1971 Intel had 500 employees;
by 1983, 21,500 employees and $1.1B in sales.
EE414 VLSI Design
The Big Bang
1970: Intel starts selling a 1k bit
RAM, the 1103. Its density and cost
make it the only game in town.
EE414 VLSI Design
1971: Ted Hoff at Intel designed the
first microprocessor. The 4004 had
4-bit busses and a clock rate of 108
KHz. It had 2300 transistors and
was built in a 10 um process.
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Exponential Growth
1972: 8088 introduced. Had 3,500
transistors supporting a bytewide data path.
1974: Introduction of the 8080. Had
6,000 transistors in a 6 um process.
The clock rate was 2 MHz.
EE414 VLSI Design
Today
Many disciplines have contributed to the current state of the
art in VLSI Design:
•Solid State Physics
•Materials Science
•Lithography and fab
•Device modeling
•Circuit design and
layout
•Architecture design
•Algorithms
•CAD tools
To come up with chips like:
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Today
Intel Pentium
•~3.5M
transistors
EE414 VLSI Design
Today
Intel Pentium Pro
•Actually a MCM comprising of
microprocessor and L2 cache
Why not make it on
one chip?
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Today
Sun UltraSparc
EE414 VLSI Design
Today
Intel Pentium II
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Intel Pentium IV
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Evolution of Electronics
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Moore’s Law
In 1965, Gordon Moore noted that the
number of transistors on a chip doubled
every 12 months.
He made a prediction that semiconductor
technology will double its effectiveness
every 18 months
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1975
1974
1972
1973
1971
1970
1968
1969
1967
1966
1964
1965
1963
1962
1960
1961
1959
LOG 2 OF THE NUMBER OF
COMPONENTS PER INTEGRATED FUNCTION
Moore’s Law
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Electronics, April 19, 1965.
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Evolution in Complexity
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Transistor Counts
1 Billion
Transistors
K
1,000,000
100,000
10,000
1,000
i486
Pentium ® III
Pentium ® II
Pentium ® Pro
Pentium ®
i386
80286
100
8086
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Source: Intel
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1975 1980
1985 1990 1995 2000
2005 2010
Projected
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Courtesy, Intel
Moore’s law in Microprocessors
Transistors (MT)
1000
2X growth in 1.96 years!
100
10
486
1
386
286
0.1
0.01
P6
Pentium® proc
8086
8080
8008
4004
8085
0.001
1970
1980
1990
Year
2000
2010
Transistors on Lead Microprocessors double every 2 years
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Courtesy, Intel
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Die Size Growth
Die size (mm)
100
10
8080
8008
4004
8086
8085
1
1970
386
286
1980
P6
486 Pentium ® proc
~7% growth per year
~2X growth in 10 years
1990
Year
2000
2010
Die size grows by 14% to satisfy Moore’s Law
EE414 VLSI Design
Courtesy, Intel
Frequency
Frequency (Mhz)
10000
Doubles every
2 years
1000
100
486
10
8085
1
0.1
1970
8086 286
P6
Pentium ® proc
386
8080
8008
4004
1980
1990
Year
2000
2010
Lead Microprocessors frequency doubles every 2 years
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Courtesy, Intel
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Power Dissipation
Power (Watts)
100
P6
Pentium ® proc
10
8086 286
1
8008
4004
486
386
8085
8080
0.1
1971
1974
1978
1985
Year
1992
2000
Lead Microprocessors power continues to increase
EE414 VLSI Design
Courtesy, Intel
Power will be a major
problem
100000
18KW
5KW
1.5KW
500W
Power (Watts)
10000
1000
100
Pentium® proc
286
8086 386486
8085
8080
8008
1 4004
10
0.1
1971 1974 1978 1985 1992 2000 2004 2008
Year
Power delivery and dissipation will be prohibitive
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Courtesy, Intel
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Power density
Power Density (W/cm2)
10000
1000
100
Rocket
Nozzle
Nuclear
Reactor
8086
10 4004
Hot Plate
P6
8008 8085
Pentium® proc
386
286
486
8080
1
1970
1980
1990
2000
2010
Year
Power density too high to keep junctions at low temp
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Courtesy, Intel
Not Only Microprocessors
Cell
Phone
Small
Signal RF
Digital Cellular Market
(Phones Shipped)
1996 1997 1998 1999 2000
Units
48M 86M 162M 260M 435M
Power
RF
Power
Management
Analog
Baseband
Digital Baseband
(DSP + MCU)
(data from Texas Instruments)
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Challenges in Digital Design
“Macroscopic Issues”
“Microscopic Problems”
• Time-to-Market
• Millions of Gates
• High-Level Abstractions
• Reuse & IP: Portability
• Predictability
• etc.
• Ultra-high speed design
• Interconnect
• Noise, Crosstalk
• Reliability, Manufacturability
• Power Dissipation
• Clock distribution.
Everything Looks a Little Different
…and There’s a Lot of Them!
EE414 VLSI Design
10,000
10,000,000
100,000
100,000,000
Logic Tr./Chip
Tr./Staff Month.
Complexity
1,000
1,000,000
10,000
10,000,000
100
100,000
Productivity
(K) Trans./Staff - Mo.
Logic Transistor per Chip (M)
Productivity Trends
1,000
1,000,000
58%/Yr. compounded
Complexity growth rate
10
10,000
100
100,000
1,0001
10
10,000
x
0.1
100
xx
x x
0.01
10
x
1
1,000
21%/Yr. compound
Productivity growth rate
x
x
0.1
100
2009
2005
2007
2003
1999
2001
1997
1995
1993
1989
1991
1987
1983
1985
0.01
10
1981
0.001
1
Source: Sematech
Complexity outpaces design productivity
EE414 VLSI Design
Courtesy, ITRS Roadmap
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Why Scaling?
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Technology shrinks by 0.7/generation
With every generation can integrate 2x more
functions per chip; chip cost does not increase
significantly
Cost of a function decreases by 2x
But …
» How to design chips with more and more functions?
» Design engineering population does not double every
two years…
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Hence, a need for more efficient design methods
» Exploit different levels of abstraction
EE414 VLSI Design
Design Abstraction Levels
SYSTEM
MODULE
+
GATE
CIRCUIT
DEVICE
G
S
n+
D
n+
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