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EE 261 Krish Chakrabarty 1 EE 261: Full Custom VLSI Design Prof. Krish Chakrabarty Dept. Electrical and Computer Engineering Room 110, Hudson Hall Ph: 660-5244 E-mail: [email protected] URL: http://www.ee.duke.edu/~krish Course URL: http://www.ee.duke.edu/~krish/teaching/261.html EE 261 Krish Chakrabarty 2 Course Objectives Introduction to CMOS VLSI design methodologies Emphasis on full-custom design Circuit and system levels Extensive use of Mentor Graphics CAD tools for IC design, simulation, and layout verification Specific techniques for designing high-speed, low-power, and easily-testable circuits
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EE 261: Full Custom VLSI Designpeople.ee.duke.edu/~krish/teaching/Lectures/Intro.pdf · EE 261 Krish Chakrabarty 8 Annual Sales •1018 transistors manufactured in 2003 – 100 million

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Page 1: EE 261: Full Custom VLSI Designpeople.ee.duke.edu/~krish/teaching/Lectures/Intro.pdf · EE 261 Krish Chakrabarty 8 Annual Sales •1018 transistors manufactured in 2003 – 100 million

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EE 261 Krish Chakrabarty 1

EE 261: Full Custom VLSI DesignProf. Krish Chakrabarty

Dept. Electrical and Computer EngineeringRoom 110, Hudson Hall

Ph: 660-5244E-mail: [email protected]

URL: http://www.ee.duke.edu/~krish

Course URL: http://www.ee.duke.edu/~krish/teaching/261.html

EE 261 Krish Chakrabarty 2

Course Objectives

• Introduction to CMOS VLSI design methodologies– Emphasis on full-custom design– Circuit and system levels

• Extensive use of Mentor Graphics CAD tools for IC design, simulation, and layout verification

• Specific techniques for designing high-speed, low-power, and easily-testable circuits

Page 2: EE 261: Full Custom VLSI Designpeople.ee.duke.edu/~krish/teaching/Lectures/Intro.pdf · EE 261 Krish Chakrabarty 8 Annual Sales •1018 transistors manufactured in 2003 – 100 million

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Designing for VLSI

• Designing a system on a chip– Craft components from silicon rather than selecting catalog parts

• ICs (chips) are batch fabricated– Inexpensive unit cost

• Bugs are hard to fix!– Extensive design verification needed

EE 261 Krish Chakrabarty 4

VLSI Design: Overview• VLSI design is system design

– Designing fast inverters is fun, but need knowledge of all aspects of digital design: algorithms, systems, circuits, fabrication, and packaging

– Need to bridge gap between abstract vision of digital design andthe underlying digital circuit and its peculiarities

– Circuit-level optimization, verification, and testing techniques are important

• Tall thin approach does not always work– Today’s designer is “fatter”, but well-versed in both high-level and

low-level design skills

Page 3: EE 261: Full Custom VLSI Designpeople.ee.duke.edu/~krish/teaching/Lectures/Intro.pdf · EE 261 Krish Chakrabarty 8 Annual Sales •1018 transistors manufactured in 2003 – 100 million

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VLSI: Enabling Technology

• Automotive electronic systems– A typical Chevrolet has 80 ICs (stereo systems, display panels, fuel

injection systems, smart suspensions, antilock brakes, airbags)

• Signal Processing (DSP chips, data acquisition systems)• Transaction processing (bank ATMs)• PCs, workstations• Medical electronics (artificial eye, implants)• Multimedia

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Design Complexity• Transistor counts and IC densities continue to

grow!– Moore’s Law-The number of transistors on an IC doubles every

1.5 years– Intel x486: 1 million transistors (1989), PowerPC: 2-3 million

transistors (1994), Pentium: 3.1 million transistors (1994), DECAlpha: 10 million transistors (1995)-9 million in SRAM, Pentium IV (2001): 42 million transistors

• Memory (DRAM) is the “technology driver”– 256 Mbits DRAM now commercially available

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A Brief History• 1958: First integrated circuit

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

• 2003– Intel Pentium 4 µprocessor (55 million transistors)– 512 Mbit DRAM (> 0.5 billion transistors)

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

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

EE 261 Krish Chakrabarty 8

Annual Sales

• 1018 transistors manufactured in 2003– 100 million for every human on the planet

0

50

100

150

200

1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002

Year

Global S

emiconductor B

illings(B

illions of US

$)

Page 5: EE 261: Full Custom VLSI Designpeople.ee.duke.edu/~krish/teaching/Lectures/Intro.pdf · EE 261 Krish Chakrabarty 8 Annual Sales •1018 transistors manufactured in 2003 – 100 million

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VLSI Technology

• CMOS: Complementary Metal Oxide Silicon– Based on voltage-controlled field-effect transistors (FETs)

• Other technologies: bipolar junction transistors (BJTs), BiCMOS, gallium arsenide (GaAs)– BJTs, BiCMOS, ECL circuits are faster but CMOS consumes

lower power and are easier to fabricate– GaAs carriers have higher mobility but high integration levels are

difficult to achieve in GaAs technology

EE 261 Krish Chakrabarty 10

Transistor Types

• Bipolar transistors– npn or pnp silicon structure– Small current into very thin base layer controls large currents

between emitter and collector– Base currents limit integration density

• Metal Oxide Semiconductor Field Effect Transistors– nMOS and pMOS MOSFETS– Voltage applied to insulated gate controls current between source

and drain– Low power allows very high integration

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IC Manufacturing• Some manufacturing processes are tightly coupled to the

product, e.g. Buick/Chevy assembly line• IC manufacturing technology is more versatile• CMOS manufacturing line can make circuits of any type

by changing some basic tools called masks– The same plant can manufacture both microprocessors and microwave

controllers by simply changing masks

• Silicon wafers: raw materials of IC manufacturing

Teststructure Wafer

IC

EE 261 Krish Chakrabarty 12

The First Computer

The BabbageDifference Engine(1832)25,000 partscost: £17,470

Page 7: EE 261: Full Custom VLSI Designpeople.ee.duke.edu/~krish/teaching/Lectures/Intro.pdf · EE 261 Krish Chakrabarty 8 Annual Sales •1018 transistors manufactured in 2003 – 100 million

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EE 261 Krish Chakrabarty 13

ENIAC - The first electronic computer (1946)

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Invention of the Transistor• Vacuum tubes ruled in first half of 20th century

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

– John Bardeen and Walter Brattain at Bell Labs– Read Crystal Fire

by Riordan, Hoddeson

Page 8: EE 261: Full Custom VLSI Designpeople.ee.duke.edu/~krish/teaching/Lectures/Intro.pdf · EE 261 Krish Chakrabarty 8 Annual Sales •1018 transistors manufactured in 2003 – 100 million

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• 1970’s processes usually had only nMOS transistors– Inexpensive, but consume power while idle– 1980s-present: CMOS processes for low idle power

MOS Integrated Circuits

Intel 1101 256-bit SRAM Intel 4004 4-bit µProc

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Moore’s Law• 1965: Gordon Moore plotted transistor on each

chip– Fit straight line on semilog scale– Transistor counts have doubled every 26 months

Year

Transistors

40048008

8080

8086

80286Intel386

Intel486Pentium

Pentium ProPentium II

Pentium IIIPentium 4

1,000

10,000

100,000

1,000,000

10,000,000

100,000,000

1,000,000,000

1970 1975 1980 1985 1990 1995 2000

Integration Levels

SSI: 10 gates

MSI: 1000 gates

LSI: 10,000 gates

VLSI: > 10k gates

Page 9: EE 261: Full Custom VLSI Designpeople.ee.duke.edu/~krish/teaching/Lectures/Intro.pdf · EE 261 Krish Chakrabarty 8 Annual Sales •1018 transistors manufactured in 2003 – 100 million

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Corollaries• Many other factors grow exponentially

– Ex: clock frequency, processor performance

Year

1

10

100

1,000

10,000

1970 1975 1980 1985 1990 1995 2000 2005

4004

8008

8080

8086

80286

Intel386

Intel486

Pentium

Pentium Pro/II/III

Pentium 4

Clock S

peed (MH

z)

EE 261 Krish Chakrabarty 18

Evolution in Complexity

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Evolution in Transistor Count

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Evolution in Speed/Performance

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Intel 4004 Micro-Processor

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Intel Pentium (II) microprocessor

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Silicon in 2010

Die Area: 2.5x2.5 cmVoltage: 0.6 VTechnology: 0.07 µm

Density Access Time(Gbits/cm2) (ns)

DRAM 8.5 10DRAM (Logic) 2.5 10SRAM (Cache) 0.3 1.5

Density Max. Ave. Power Clock Rate(Mgates/cm2) (W/cm2) (GHz)

Custom 25 54 3Std. Cell 10 27 1.5

Gate Array 5 18 1Single-Mask GA 2.5 12.5 0.7

FPGA 0.4 4.5 0.25

EE 261 Krish Chakrabarty 24

Design Abstraction Levels

n+n+S

GD

+

DEVICE

CIRCUIT

GATE

MODULE

SYSTEM

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New Design Challenges• Interconnect-centric design

– Capacitive coupling, inductance effects, delay modeling• Power densities, power grid design, leakage

– 80 W/cm2 ∼ 100 W/cm2

• Nuclear reactor: 150 W/cm2

– 80% increase in power density per generation (voltage scales by 0.8)

– 225% increase in current density– 1.3V power supply leads to 60W power with 60A

sustained current• 2X the current (surge) in your car’s alternator

• Statistical design (P,V,T)