An integrated circuit (IC) is a piece of semiconductor material, most commonly silicon and often referred to as a chip. 

Circuit components are built into and on one face (monolithic) and inter-connected by metal tracks to form a complex electrical circuit. 

Key features are small size, high complexity, low cost and very high reliability. 

Penalties are limited range of component values available and unwanted interactions caused by close proximity of circuit components on the same chip. 

IC designer’s role is to achieve required circuit functionality despite IC limitations due to unwanted interactions.

Typically 1 cm 

1 cm 

Containing up to 1 million components

• First ICs developed in 1958 by Jack Kilby of  Texas Instruments.

• Development of IC a result of the development of the first transistor by Shockly, Bardeen and Brattain at Bell Laboratories in 1947.

• Initial ICs consisted of only a few transistors and resistors but offered advantages on systems, based on thermionic values, used in computers at that time in terms of reduced size, improved reliability and reduced power.

• Technological improvements now enable chips to be designed containing up to 10 million transistors referred to as Very Large Scale Integration (VLSI).
  
  Scale of increase of complexity (number of transistors on a chip) often expressed as complexity doubles every 2.2 years (Moore’s Law) - shown diagrammatically over the last 35 years in Graph 1. Some recent evidence that the increase in complexity is slowing down becoming more of a curve than a straight line (see graph 1)
   
   

Graph 1 - Integrated circuit complexity versus time

What’s CMOS ?

        Complementary Metal-Oxide Semiconductors (CMOS) logic devices are the most common devices used today in the high density, large number transistor count circuits found in everything from complex microprocessor integrated circuits to signal processing and communication circuits. The CMOS structure is popular because of its inherent lower power requirements, high operating clock speed, and ease of implementation at the transistor level. Students in introductory electronic circuits classes can gain insight into the operation of these CMOS devices through a few exercises in constructing simple CMOS combinational logic circuits such as AND, NAND gates, OR, NOR gates and INVERTERS. These circuits are created using both p and n-channel Metal-Oxide Semiconductor Field Effect Transistors (MOSFET) connected in complementary configurations.

The complementary p-channel and n-channel transistor networks are used to connect the output of the logic device to the either the V_DD or V_SS power supply rails for a given input logic state. In a simplified view, the MOSFET transistors can be treated as simple switches. This is adequate for an introduction to simple CMOS circuits where switching speeds, propagation delays, drive capability, and rise and fall times are of little concern.

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