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Monday, November 24, 2014

Intergrated circuit(IC)


Intergrated circuit(IC) in Modern Electronics


An intergrated circuit is an electronic circuit in which allthe active and passive components are fabricated on a single crystal chip.
The area of Silcon Chip is 50 X 50 mils*
*mil = 25/1000000 m.

Analog IC(Linear IC)


An Analog IC is one which performs amplification or other essentially linear operations on signals. Hence it is also known as linear IC. An analog IC deals with continuously varying quantities such as temperature, pressure.
Examples : Simple amplifier, Operational amplifier etc.

Digital IC(Non-Lineae IC)


In digital IC, information is represented by binary digits, bits. A bit assume either one of two values : 0 or. It is based on a mathematical system that uses that uses only two digit and is called a binary system. Digital circuit generally require only "on-off" operation of transistors, the design requirements for digital ICs are often less stringent than for analog circuits.
Examples : Computers, Calculators

Advantage of ICs


Size and Weight


IC technology offers reduction in size i.e. miniaturization and weight of the circuit. This is obvious because a circuit made of large number of discrete components can be deposited on a chip which is housed in a package similar to that used for the encapsulation of discrete transistor. Such equipments can be suitably, employed in many apllications where weight and space are critical, such as aircraft or space vehicles and medical electronics.

Increase of Reliability


Unlike discrete component circuits where individual transistor and other components wired together or placed on a circuit board, IC allows many extra components to be included economically. This back up circuitry can be included in the product, making it more reliable. Such extra addition of component does not raise greatly the cost of the product.

Reduction in Circuit Cost


The processing steps for the wafer may be involved and expensive, the larger number of resulting circuits makes the ultimate cost of each fairly. The processing steps are essentially the same for a circuit containing 1000 transistors as for a simple 100 transistor circuit. This means that the number of components in each circuit is relatively unimportant in terms of the ultimate cost of the system.

Reduction in Power Consumption


It is something difficult to fully appreciate the revolutionary changes that were made possible through the development of ICs. For example, the largest early computers occupied a volume of hundreds of cubic meters and required many kilowatts of electrical power and a sizable air-conducting plant to allow this amount of energy to be dissipate without raising the room temperature to undesirable values. This drastic reduction in power consumption is not only due to IC technology but also due to on-off switching operation.

Improvement in speed


The signal propagation time is longer on connections made on printed circuit board than on connections inside, the chip. Also, by making the physical size of the entire digital system small, the speed is improved.


Types of IC


There are several ways of categorizing ICs as their use and methods of fabricates. The most common categories based on fabrication are
(1)Monolithic IC
(2)Hybrid IC

(1)Monolithic Circuits


Intergrated circuits which are included entirely in a single chip of semi conductor are called Monolithic circuit. The word monolithic literally means "one stone" and implies that the entire circuit is conducted in a single piece of semiconductor.


Hybird Circuits


Hybird circuit one or more monolithic circuit or individual transistors bonded to an insulating substrate with resistors, capacitors or other circuit elements with appropriate inter-connections. When resistors and capacitors are made external to monoliyhic silicon chip, basically two types of technolgy are used, the passive elements are fabricated and interconnected by thick-film process. The dividing line between thin and thick films is not precise. In thick-film type hybird circuits, the resistors and interconnection patterns are printed on a ceramic substrate. Thin film interconnection patterns and resistors can be deposited vacuum evaporation technique on a glass ceramic substrate.


Application of Linear or Analog IC


1)In DC Amplifier
2)In video Amplifier
3)In Modulator
4)In Voltage regulator


Application of Non-linear or digital IC


1)In logic circuit
2)In computer
3)In memory
4)In calculatorss



  

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