Basics of VLSI

Introduction:

Invention of the transistor was the driving factor of growth in the VLSI technology. Before we get to know about the VLSI technology, let us have a basic knowledge of ELECTRONICS evolution. Electronics deals with circuits which involves active and passive components. These circuits are used in various Electronics Devices and are called Electronic Circuits.The components used in Electronic circuits are Diodes, Transistors, MOSFET'S. In the VLSI we will mainly concentrate on three factors they are: 1. AREA  2. POWER  3. TIMING.

Integrated Circuit:

Integrated Circuit is the circuit in which all the Passive and Active components are fabricated onto a single chip. Initially the Integrated Chip could accommodate only a few components. As the days passed, the devices became more complex and required more number of circuits which made the devices look bulky. Instead of accommodating more circuits in the system, an integration technology was developed to increase the number of components that are placed on a single chip. This technology not only helped to reduce the size of the devices but also improved the speed depending on the number of components to be integrated, they are categorized as SSI, MSI, LSI, VLSI, ULSI.

Small Scale Integration (SSI):
In this technology, 1-100 transistors were fabricated on a single chip, eg: Gates, Flip flops.

Medium Scale Integration (MSI):
Using this technology 100-1000 number of transistors could be integrated on a single chip. Eg: 4-bit micro processor.

Large Scale Integration (LSI):
Using this technology, 1000-10000 transistors could be integrated on a single chip. Eg: 8 bit Micro processor, RAM, ROM.

Very Large Scale Integration (VLSI):
In this technology, 10000-1 Million transistors could be accommodated. Eg: 16-32 bit Micro processors.

Ultra Large Scale Integration (ULSI):
In this technology, 1 Million- 10 Million transistors could be accommodated. Eg: Special Purpose Registers.

Moore's Law:

In 1965, Gordon Moore, an industry pioneer predicted that the number of transistors on a chip doubles every 18 to 24 months. He also also predicted that semiconductor technology will double its effectiveness every 18 months and many other factors grows exponentially.

Advantages of VLSI:

1. Higher Reliability

2. Increase the Operating speed of the circuit

3. Requires less power.

4. Reduces the size of the chip.