INTRODUCTION TO VLSI

Author - personEngineering Lecture Notes Pdf

March 04, 2024

In 1958, Jack Kilby built the first integrated circuit flip-flop at Texas Instruments.
Bell Labs developed the bipolar junction transistor. Bipolar transistors were more reliable, less noisy and more power-efficient.
In 1960s, Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) began to enter in the production.
MOSFETs offer the compelling advantage that; they draw almost zero control current while idle.
They come in two flavors: nMOS and pMOS, using n-type and p-type silicon respectively.
In 1963, Frank Wanlass at Fairchild described the first logic gates using MOSFETs.
Fairchild’s gates used both nMOS and pMOS transistors, naming as Complementary Metal Oxide Semiconductor (CMOS).
Power consumption became a major issue in the 1980s as hundreds of thousands of transistors were integrated onto a single die.
CMOS processes were widely adopted and replaced nMOS and bipolar processes for all digital logic applications.
In 1965, Gordon Moore observed that plotting the number of transistors that can be most economically manufactured on a chip gives a straight line on a semi logarithmic scale.

o Moore’s Law is defined as transistor count doubling every 18 months.

The level of integration of chips is classified as

1. Small scale Integration:

Small-Scale Integration (SSI) circuits have less than 10 gates. Example: 7404 inverter.

Medium-Scale Integration (MSI) circuits have up to 1000 gates. Example: 74161 counter.

Large-Scale Integration (LSI) circuits have up to 10,000 gates. Example: 8-bit microprocessor (8085).

Very large scale Integration (VLSI) with gates counting up to lakhs. Example: 16-bit microprocessor (8086).

The feature size of a CMOS manufacturing process refers to the minimum dimension of a transistor that can be reliably built.

Ultra Large-Scale Integration (ULSI) is the process of integrating millions of transistors on a single silicon semiconductor microchip.