12.1 INTRODUCTION

In electronics, an integrated circuit (also known as IC, microcircuit, microchip, silicon chip or chip) is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that is manufactured on the surface of a thin substrate of semiconductor material. A hybrid Integrated Circuit is a miniaturized electronic circuit constructed of individual semiconductor devices, as well as passive components, bonded to a substrate or circuit board. Integrated circuits are used in almost all electronic equipment and have revolutionized the world of electronics.

To a large extent, the demand for miniaturization was driven by the demands of the American Space Program. For some time, people had been thinking that it would be a good idea to be able to fabricate an entire circuit on a single piece of semiconductor. The first public discussion of this idea is credited to a British radar expert, Geoffrey William Arnold Dummer (1909–2002), in a paper presented in 1952. Jack Kilby's first prototype was a phase-shift oscillator comprising of five components on a piece of germanium, half an inch long and thinner than a toothpick. Although manufacturing techniques subsequently took different paths from those used by Kilby, yet he is considered as the pioneer in the area of IC fabrication.

ICs are polarized and every pin is unique in terms of both location and function. Most ICs use either a notch or a dot to indicate the pin numbers and its counting sequence. This is depicted in Figure 12.1.

12.2 IC: ADVANTAGES AND DISADVANTAGES

The main advantages of ICs over those made by interconnecting discrete components are as follows:

• 1. Extremely small size, i.e. thousands times smaller than discrete circuits. It is because of fabrication of various circuit elements on a single chip of semiconductor material.

• 2. Very small weight owing to miniaturized circuit.

• 3. Very low cost because of simultaneous production of hundreds of similar circuits on a small semiconductor wafer. Owing to mass production, IC costs as much as an individual transistor.

• 4. More reliable because of elimination of soldered joints and need for fewer interconnections.

• 5. Lower power consumption because of their smaller size.

• 6. Easy replacement as it is more economical to replace them than to repair them.

• 7. Increased operating speed because of absence of parasitic capacitance effect.

• 8. Close matching of components and temperature coefficients because of bulk production in batches.