vlsi circuit design

1. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
Introduction to VLSI Design
 Instructor: Steven P. Levitan levitan@ee.pitt.edu
 TA: Jeremiah Cessna jecst40@pitt.edu
 Book: Digital Integrated Circuits: A Design
Perspective; Jan Rabaey
 Lab Notes: at Copycat
 http://kona.ee.pitt.edu/steve/EE1192
 http://infopad.EECS.Berkeley.EDU/~icdesign/

2. Jan M. Rabaey
Digital Integrated Circuits
A Design Perspective

3. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
Course Outline (approximate)
– Introduction and Motivation
– The VLSI Design Process
– Details of the MOS Transistor
– Device Fabrication
– Design Rules
– CMOS circuits
– VLSI Structures
– System Timing
– Real Circuits and Performance

4. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
Reference Books
– Principles of CMOS VLSI Design: Neil Weste
and Kamran Eshraghian
– CMOS: Baker, Li, Boyce
– Application Specific Integrated Circuits: Smith
– The Design and Analysis of VLSI
– Circuits: Lance Glasser and Daniel Dobberpuhl
– Introduction to VLSI Systems: Carver Mead &
Lynn Conway
– NewsGroups: comp.lsi, comp.lsi.cad

5. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
Software
– Magic
 Unix Based
 Interactive Design Rule Checking
 Circuit Extraction
 Supported Technology files
– Spice
 Well known and disliked
 Spice 3 allows user models
 Good support/documentation
 Interface with Magic extraction
– Irsim
 Switch / Switched - Resistor level
 Fast functional validation
 Good interface with Magic

6. The First Computer
The Babbage
Difference Engine
(1832)
25,000 parts
cost: £17,470
Digital Integrated Circuits © Prentice Hall 1995
Introduction

7. ENIAC - The first electronic computer
(1946)
Digital Integrated Circuits © Prentice Hall 1995
Introduction

8. Evolution in Complexity
Digital Integrated Circuits © Prentice Hall 1995
Introduction

9. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
What is “CMOS VLSI”?
– MOS = Metal Oxide Semiconductor (This used
to mean a Metal gate over Oxide insulation)
– Now we use polycrystalline silicon which is
deposited on the surface of the chip as a gate.
We call this “poly” or just “red stuff” to
distinguish it from the body of the chip, the
substrate, which is a single crystal of silicon.
– We do use metal (aluminum) for interconnection
wires on the surface of the chip.

10. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
CMOS:Complementary MOS
– Means we are using both N-channel and P-
channel type enhancement mode Field Effect
Transistors (FETs).
– Field Effect- NO current from the controlling
electrode into the output
 FET is a voltage controlled current device
 BJT is a current controlled current device
– N/P Channel - doping of the substrate for
increased carriers (electrons or holes)

11. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
N-Channel Enhancement
mode MOS FET
– Four Terminal Device - substrate bias
–The “self aligned gate” - key to CMOS

12. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
VLSI:Very Large Scale
Integration
 Integration: Integrated Circuits
» multiple devices on one substrate
 How large is Very Large?
– SSI (small scale integration)
 7400 series, 10-100 transistors
– MSI (medium scale)
 74000 series 100-1000
– LSI 1,000-10,000 transistors
– VLSI > 10,000 transistors
– ULSI/SLSI (some disagreement)

13. Intel 4004 Micro-Processor
Digital Integrated Circuits © Prentice Hall 1995
Introduction

14. Evolution in Transistor Count
Digital Integrated Circuits © Prentice Hall 1995
Introduction

15. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
Scale Example
 Consider a chip size of 20mm X 20mm
 Consider a transistor size of 2um X 2um
» With area for wires, etc.
 1x108 transistors / chip
 Or - plot at 1 transistor : 1 mm
– 1 chip : 20 meter x 20 meter plot

16. Intel Pentium (II) microprocessor
Digital Integrated Circuits © Prentice Hall 1995
Introduction

17. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
VLSI Design
– But the real issue is that VLSI is about
designing systems on chips.
– The designs are complex, and we need to use
structured design techniques and sophisticated
design tools to manage the complexity of the
design.
– We also accept the fact that any technology we
learn the details of will be out of date soon.
– We are trying to develop and use techniques
that will transcend the technology, but still
respect it.

18. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
The Process of VLSI Design:
Consists of many different representations/Abstractions
of the system (chip) that is being designed.
– System Level Design
– Architecture / Algorithm Level Design
– Digital System Level Design
– Logical Level Design
– Electrical Level Design
– Layout Level Design
– Semiconductor Level Design (possibly more)
Each abstraction/view is itself a Design Hierarchy of
refinements which decompose the design.

19. Design Abstraction Levels
n+
n+
S
G
D
+
DEVICE
CIRCUIT
GATE
MODULE
SYSTEM
Digital Integrated Circuits © Prentice Hall 1995
Introduction

20. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
Help from Computer Aided
Design tools
 Tools
» Editors
» Simulators
» Libraries
» Module Synthesis
» Place/Route
» Chip Assemblers
» Silicon Compilers
 Experts
» Logic design
» Electronic/circuit
design
» Device physics
» Artwork
» Applications - system
design
» Architectures

21. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
New Design Methodologies
 Methodologies which are based on:
» System Level Abstractions v.s. Device
Characteristic Abstractions
– Logic structures and circuitry change slowly
over time
 trade-offs do change, but the choices do not
» Scalable Designs
– Layout techniques also change slowly.
 But the minimum feature size steadily decreases with
time (also Voltage, Die Size, etc.)

22. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
Design Approaches
– Custom
 full control of design
 best results, slowest design time.
– Semi-custom (std cell)
 use Cell libraries from vendor
 cad tools, faster design time
– Gate Array
 fastest design time
 worst speed/power/density
 best low volume (worst high volume)
– EPLA/EPLD - FPGA - electrically programmable
(in the field) -

23. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
Close up of Intel Chip?
Time Magazine, July 1998

24. Evolution in Speed/Performance
Digital Integrated Circuits © Prentice Hall 1995
Introduction

25. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
Technologies
– Bipolar (BJT)
 TTL, Schottky
 ECL
 I^2 L
– Dual Junction, current controlled devices
 MOS (FET unipolar)
» NMOS, PMOS
» CMOS <== our course
– Single Junction voltage controlled devices
 GaAs (typically JFET’s)
 OEIC’s - MQW’s, Integrated Lasers,?

26. Silicon in 2010
Die Area: 2.5x2.5 cm
Voltage: 0.6 V
Technology: 0.07 m
Dens
ity Acces
sTime
(Gbits
/cm2) (ns
)
DRAM 8.5 10
DRAM (Logic) 2.5 10
SRAM (Cache) 0.3 1.5
Dens
ity Max. Ave. Power Clock Rate
(Mgates
/cm2) (W /cm2) (GHz)
Cus
tom 25 54 3
Std. Cell 10 27 1.5
GateArray 5 18 1
Single-Mas
k GA 2.5 12.5 0.7
FPGA 0.4 4.5 0.25
Digital Integrated Circuits © Prentice Hall 1995
Introduction

27. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
SIA -National Technology
Roadmap for Semiconductors

28. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
SIA -National Technology
Roadmap for Semiconductors
8 inch 18 inch

29. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
SIA -National Technology
Roadmap for Semiconductors

30. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
SIA -National Technology
Roadmap for Semiconductors

31. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
SIA -National Technology
Roadmap for Semiconductors

32. Introduction to VLSI Design © Steven P. Levitan 1998
Introduction
SIA -National Technology
Roadmap for Semiconductors