Integrated Circuits

An integrated circuit (IC), sometimes called a chip or microchip, is a semiconductor wafer on which thousands or millions of tiny resistors, capacitors, and transistors are fabricated. An IC can function as an amplifier, oscillator, timer, counter, computer memory, or microprocessor. A particular IC is categorized as either linear analog or digital, depending on its intended application. IC's are are of Linear , digital and mixed types Linear ICs have continuously variable output (theoretically capable of attaining an infinite number of states) that depends on the input signal level. As the term implies, the output signal level is a linear function of the input signal level. Linear ICs are used as audio-frequency (AF) and radio-frequency (RF) amplifiers. The operational amplifier (op amp) is a common device in these applications. Digital ICs operate at only a few defined levels or states, rather than over a continuous range of signal amplitudes. These devices are used in computers, computer networks, modems, and frequency counters. The fundamental building blocks of digital ICs are logic gates, which work with binary data, that is, signals that have only two different states, called low (logic 0) and high (logic 1). Applications and Uses of Integrated Circuits
The advantages of Integrated Circuits are:
1. Very small size: Hundred times smaller than the discrete circuits.
2. Lesser weight: As large number of components can be packed into a single chip, weight is reduced
3. Reduced cost: The mass production technique has helped to reduce the price, 
4. High reliability: Due to absence of soldered connection, few interconnections and small temperature rise failure rate is low. 5. Low power requirement: As the size is small power consumption is less.
6. Easy replacement: In case of failure chip can easily be replaced.  Linear IC's also known as analog
Integrated circuits are:
1. Power amplifiers
2. Small-signal amplifiers
3. Operational amplifiers
4. Microwave amplifiers
5. RF and IF amplifiers
6. Voltage comparators
7. Multipliers
8. Radio receivers
9. Voltage regulators

Digital IC's are mostly used in computers. They are also referred as switching circuits because their input and output voltages are limited to two levels - high and low i.e. binary.
They include:
1. Flip-flops     
2. Logic gates
3. Timers
4. Counters
5. Multiplexers
6. Calculator chips
7. Memory chips
8. Clock chips
9. Microprocessors
10. Microcontrollers
11. Temperature sensors

Mixed type applications - cars (automotive controls), televisions, computers, microwaves, portable devices like laptops, MP3, play stations, cameras, cellular phones to ship equipments, aero planes, space craft’s. These are also used in switching telephone circuits and data processing. They also found applications in military equipments. The most common application of IC is digital watch which tells hour, second, minute, day and month. Another common but important application is scientific calculator which can perform basic functions like addition, subtraction, multiplication and division as well as complex functions like square root, cube, permutations, combinations , trigonometric functions, etc