The document provides an overview of Very Large Scale Integration (VLSI) and its significance in the development of microprocessors, essential components in everyday electronics. It traces the evolution of microprocessors from early computers reliant on vacuum tubes to modern integrated circuits, showcasing the advancement in technology and the miniaturization of components. VLSI technology, which allows thousands of transistors to be combined on a single chip, has played a crucial role in enhancing computer performance, reducing costs, and expanding their applications across various devices.

1. Introduction to VLSI Circuits and
Systems
4th
Generation Microprocessor
VLSI
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2. The beginning
 Microprocessors are essential to many of the products we use every day such as TVs, cars, radios,
home appliances and of course, computers. Transistors are the main components of
microprocessors.
 At their most basic level, transistors may seem simple. But their development actually required
many years of painstaking research. Before transistors, computers relied on slow, inefficient
vacuum tubes and mechanical switches to process information. In 1958, engineers managed to put
two transistors onto a Silicon crystal and create the first integrated circuit, which subsequently led
to the first microprocessor.
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3. History and Evolution
 In 1976, Steve Jobs and Steve Wozniak built the Apple II, the first personal computer in a garage
in California.
 Then, in 1981, IBM introduced its first personal computer. The personal computer was such a
revolutionary concept and was expected to have such an impact on society that in 1982, "Time"
magazine dedicated its annual "Man of the Year Issue" to the computer. The other feature of the
microprocessor is its versatility. Whereas previously the integrated circuit had had to be
manufactured to fit a special purpose, now one microprocessor could be manufactured and then
programmed to meet any number of demands. Soon everyday household items such as microwave
ovens, television sets and automobiles with electronic fuel injection incorporated microprocessors.
 The 1980's saw an expansion in computer use in all three arenas as clones of the IBM PC made the
personal computer even more affordable. The number of personal computers in use more than
doubled from 2 million in 1981 to 5.5 million in 1982. Ten years later, 65 million PCs were being
used. Computers continued their trend toward a smaller size, working their way down from
desktop to laptop computers (which could fit inside a briefcase) to palmtop (able to fit inside a
breast pocket).
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4.  Integration improves the design
 Lower parasitics = higher speed
 Lower power consumption
 Physically smaller
 Integration reduces manufacturing cost - (almost) no manual assembly
Why VLSI?
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5. Introduction
Very-large-scale integration (VLSI) is the process of creating an IC by combining thousands of
transistors into a single chip. VLSI began in the 1970s when complexsemiconductor and
communication technologies were being developed. The microprocessor is a VLSI device. Before
the introduction of VLSI technology most ICs had a limited set of functions they could perform.
An electronic circuit might consist of a CPU, ROM, RAM and other glue logic. VLSI lets IC
makers add all of these into one chip.
By the 1980's, very large scale integration (VLSI) squeezed hundreds of thousands of components
onto a chip. The ability to fit so much onto an area about half the size of a U.S. dime helped diminish
the size and price of computers. It also increased their power, efficiency and reliability. Marcian Hoff
invented a device which could replace several of the components of earlier computers, the
microprocessor. The microprocessor is the characteristic of fourth generation computers, capable of
performing all of the functions of a computer's central processing unit. The reduced size, reduced
cost, and increased speed of the microprocessor led to the creation of the first personal computers.
Until now computers had been the almost exclusively the domain of universities, business and
government.
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6. Introduction
IC: Integrated Circuits, many transistors on one chip
VLSI: Very Large Scale Integration, a modern
technology of IC design flow
MOS: Metal-Oxide-Silicon transistor (also called
device)
CMOS: Complementary Metal Oxide Semiconductor
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7. Moore’s Law
Gordon Moore: co-founder of Intel
Predicted that the number of transistors per chip would grow
exponentially (double every 18 months)
Exponential improvement in technology is a natural trend:
e.g. Steam Engines - Dynamo - Automobile
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8. Technology Background
What is a Silicon Chip?
A pattern of interconnected switches and gates on the surface of a crystal
of semiconductor (typically Si)
These switches and gates are made of
areas of n-type silicon
areas of p-type silicon
areas of insulator
lines of conductor (interconnects) joining areas together
Aluminium, Copper, Titanium, Molybdenum, polysilicon, tungsten
The geometryof these areas is known as the layout of the chip
Connections from the chip to the outside world are made around the edge
of the chip to facilitate connections to other devices
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9. Technology Background
Semiconductors and Doping
•Adding trace amounts of certain materials to semiconductors alters the crystal
structure and can change their electrical properties
in particular it can change the number of free electrons or holes
•N-Type
semiconductor has free electrons
dopant is (typically) phosphorus, arsenic, antimony
•P-Type
semiconductor has free holes
dopant is (typically) boron, indium, gallium
Dopants are usually implanted into the semiconductor using Implant Technology,
followed by thermal process to diffuse the dopants
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10. Silicon Lattice
Transistors are built on a silicon substrate
Silicon is a Group IV material
Forms crystal lattice with bonds to four neighbors
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11. Dopants
Silicon is a semiconductor
Pure silicon has no free carriers and conducts poorly
Adding dopants increases the conductivity
Group V: extra electron (n-type)
Group III: missing electron, called hole (p-type)
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12. Complexity and Design
 Creating a design team provides a realistic
approach to approaching a VLSI project, as it
allows each person to study small sections of the
system
 Needing hundreds of engineers, scientists, and
technicians
 Needing hierarchy design and many different “Level
Views”
 Everyone of each level depends upon the Computer-
Aided Design (CAD) tools
Figure 1.1 The VLSI design funnel
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13. Design Hierarchy (1/2)
 System specifications: is defined in both general and
specific terms, such as functions, speed, size, etc.
 Abstract high-level model: contains information on the
behavior of each block and the interaction among the
blocks in the system
 Logic synthesis: To provide the logic design of the
network by specifying the primitive gates and units needed
to build each unit
 Circuit design: where transistors are used as switches and
Boolean variables are treated as vary voltage signals
 Physical design: the network is built on a tiny area on a
slice of silicon
 Manufacturing: a completed design process is moved on to
the manufacturing line Figure 1.2 General overview
of the design hierarchy
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14. Design Hierarchy (2/2)
 Hierarchical design
 Top-down design
 the initial work is quite abstract and
theoretical and there is no direct
connection to silicon until many steps
have been completed
 Acceptable in modern digital system
design
 Co-design with combining HW/SW is
critical
 Similar to Cell-based Design Flow
 Bottom-up design
 starts at the silicon or circuit level and
builds primitive units such as logic gates,
adders, and registers as the first steps
 Acceptable for small projects
 Similar to Full-custom Design Flow
 An example of a design hierarchy in
Figure 1.3
 an instruction design of a microprocessor
Figure 1.3 A simple design
flow for a microprocessor
BA +←Register_X
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15. VLSI Chip Types
At the engineering level, digital VLSI chips are classified by
the approach used to implement and build the circuit
 Full-custom Design: where every circuit is custom designed for the
project
 Extremely tedious
 Time-consuming process
 Application-Specific Integrated Circuits (ASICs): using an
extensive suite of CAD tools that portray the system design in terms of
standard digital logic constructs
 Including state diagrams, functions tables, and logic diagram
 Designer does not need any knowledge of the underlying electronics or the
physic of the silicon chip
 Major drawback is that all characteristics are set by the architectural design
 Semi-custom Design: between that of a full-custom and ASICs
 Using a group of primitive predefined cells as building blocks, called cell
library
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16. Integrated Circuits
SSI – Small-Scale Integration (0-102
)---1960
MSI – Medium-Scale Integration (102
-103
)---1967
LSI – Large-Scale Integration (103
-105
)---1972
VLSI – Very Large-Scale Integration (105
-107
)---1978
ULSI – Ultra Large-Scale Integration (>=107
)---1989
GSI _ Giant Scale Integration (>=109
)---2000
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17. Integrated Circuits
Why Make Ics ?
 Integration improves
 size
 speed
 power
 Integration reduce manufacturing costs
 (almost) no manual assembly
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18. IC Evolution (1/3)
 SSI – Small Scale Integration (early 1970s)
 contained 1 – 10 logic gates
 MSI – Medium Scale Integration
 logic functions, counters
 LSI – Large Scale Integration
 first microprocessors on the chip
 VLSI – Very Large Scale Integration
 now offers 64-bit microprocessors,
complete with cache memory (L1 and often L2),
floating-point arithmetic unit(s), etc.
 Bipolar technology
 TTL (transistor-transistor logic)
 ECL (emitter-coupled logic)
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19. IC Evolution (2/3)
 MOS (Metal-oxide-silicon)
 although invented before bipolar transistor,
was initially difficult to manufacture
 nMOS (n-channel MOS) technology developed in 1970s
required fewer masking steps, was denser, and consumed less power than equivalent bipolar
ICs => an MOS IC was cheaper than a bipolar IC and led to investment and growth of the
MOS IC market.
 aluminum gates for replaced by polysilicon by early 1980
 CMOS (Complementary MOS): n-channel and p-channel MOS transistors =>
lower power consumption, simplified fabrication process
 Bi-CMOS - hybrid Bipolar, CMOS (for high speed)
 GaAs - Gallium Arsenide (for high speed)
 Si-Ge - Silicon Germanium (for RF)
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20. IC
From Howe, Sodini: Microelectronics:An Integrated Approach, Prentice Hall
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21. Chips
Integrated circuits consist of:
 A small square or rectangular “die”, < 1mm thick
 Small die: 1.5 mm x 1.5 mm => 2.25 mm2
 Large die: 15 mm x 15 mm => 225 mm2
 Larger die sizes mean:
 More logic, memory
 Less volume
 Less yield
 Dies are made from silicon (substrate)
 Substrate provides mechanical support and electrical common point
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22. Current Processors
Pentium® 4
42M transistors / 1.3-1.8GHz /
49-55W
L=0.18µm
Pentium® 4 “Northwood”
55M transistors / 2-2.5GHz
L=0.13µm
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23. VLSI-Chip Manufacturing
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24. References:-
1. AUTHOR STREAM:
http://www.authorstream.com/Presentation/aSGuest43958-383515-vlsi-spdas1vlsibput-education-ppt-powerpoint/
2. SLIDE SHARE:
http://www.slideshare.net/illpa/introduction-to-vlsi
3. ENGINEERS GARAGE: -
http://www.engineersgarage.com/articles/vlsi-design-future
4. FORCEPERFECT:
http://www.forcedperfect.net/hardware/cards/applepowermacintoshupgradecard/images/applepowermacintoshupgradecard-vlsi.jpg
5. Uyemura, John P.
Introduction to VLSI Circuits and Systems
6. http://www.cs.sun.ac.za/museum/gen4.html
7. http://www.youtube.com/watch?v=hO455B9d7zY
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