vlsi

Introduction to VLSI Circuits and Systems

4th Generation Microprocessor VLSI

Prepared by: Soma.O.Muhammad

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.

Monday, April 10, 2023

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Prepared by:Soma.O.Muhammad

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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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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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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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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Moore’s Law

Gordon Moore: co-founder of IntelPredicted 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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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 siliconareas of p-type siliconareas 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 chipConnections 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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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 electronsdopant is (typically) phosphorus, arsenic, antimony

•P-Typesemiconductor has free holesdopant 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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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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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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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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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 hierarchyMonday, April 10, 2023

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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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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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Integrated Circuits

SSI – Small-Scale Integration (0-102)---1960MSI – Medium-Scale Integration (102-103)---1967LSI – Large-Scale Integration (103-105)---1972VLSI – Very Large-Scale Integration (105-107)---

1978ULSI – Ultra Large-Scale Integration (>=107)---

1989GSI _ Giant Scale Integration (>=109)---2000


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Integrated Circuits

Why Make Ics ? Integration improves

size speed power

Integration reduce manufacturing costs (almost) no manual assembly


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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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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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IC

From Howe, Sodini: Microelectronics:An Integrated Approach, Prentice Hall


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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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Current Processors

Pentium® 442M transistors / 1.3-1.8GHz / 49-

55WL=0.18µm

Pentium® 4 “Northwood”55M transistors / 2-2.5GHz

L=0.13µm


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VLSI-Chip Manufacturing

Monday, April 10, 2023Prepared by:Soma.O.Muhammad

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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 Systems6. http://www.cs.sun.ac.za/museum/gen4.html7. http://www.youtube.com/watch?v=hO455B9d7zY


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vlsi

Devices & Hardware

chip vlsi

silicon chip

generation microprocessor

number of personal computers

vlsi device

generation computers

vlsi circuits

laptop computers