An integrated circuit (IC) consists of several interconnected transistors,resistors,capacitors etc.,all contained in one small package with external connecting terminals. The circuit may be entirely self-contained,requiring only input and output connections and supply voltage to function. Alternatively,a few external components may have to be connected to make the circuits operative.
on the basis of fabrication techniques used, the ICs can be divided into following three classes.
1. Monolithic ICs. The word 'monolithic' is derived from the Greek momos, meaning 'single' and lithos,meaning 'stone' and implies that the entire circuit is fabricated on a single chip of a semiconductor.In monolithic ICs,the components like transistors,diodes,resistors and capacitors are formed simultaneously by diffusion process steps.Then,the process of metallization is used in interconnecting these components to from the required circuit. The dielectric or P-N junction is used to provide electrical isolation in monolithic identical ICs are by far the most common type of ICs used in practice,because of mass production,lower cost and higher reliabilty.
since their invention,manufacturers have been manufacturing monolithic ICs to carry out all types of functions. commercially available ICs of this type can be used as amplifiers, voltage regulators,crowbars,AM receivers,TV circuits,and computer circuits.
However,the monolithic circuits have the following limitations or drawbacks:
(i) Low power rating.since monolithic ICs are of about the size of a discrete small-signal transistor,they typically have a maximum power rating of less than 1 watt.This limits their use to low-power applications.
(ii)poorer isolation between components.
(iii) No possibility of fabrication of inductors.
(iv)small range of values of passive components used in the ICs.
(v)Lack of flexibility in circuits design as for making any variation in the circuit, a new set of marks is required.
2. Thin and Thick Film ICs. These devices are larger than monolithic ICs but smaller than discrete circuits. These ICs can be used when power requirement is comparatively higher.with a thin-or thick-film IC,the passive cmponents like resistors and capacitors are integrated, but the transistors and diodes are connected as discrete components to from a complete circuit.Therefore,commercially available thin and thick-film circuits are combination of integrated and discrete components.
The essential difference between the thin- and thick-film ICs is not their relative thickness but method of deposition of film.Both have similar appearance,properties and general characteristics.
Thin-Film ICs are fabricated by depositing films of conducting material on the surface of a glass or ceramic base. By controlling the width and thickness of the films,and by using different materials selected for their resistivity, resistors and conductors are fabricated.capacitors are produced by sandwiching a film of insulating oxide between two conducting films,Inductors are made by depositing a spiral formation of film. Transistors and diodes can be produced by thin-film technology;but usually tiny discrete components are connected into the crcuit.
on the basis of fabrication techniques used, the ICs can be divided into following three classes.
1. Monolithic ICs. The word 'monolithic' is derived from the Greek momos, meaning 'single' and lithos,meaning 'stone' and implies that the entire circuit is fabricated on a single chip of a semiconductor.In monolithic ICs,the components like transistors,diodes,resistors and capacitors are formed simultaneously by diffusion process steps.Then,the process of metallization is used in interconnecting these components to from the required circuit. The dielectric or P-N junction is used to provide electrical isolation in monolithic identical ICs are by far the most common type of ICs used in practice,because of mass production,lower cost and higher reliabilty.
since their invention,manufacturers have been manufacturing monolithic ICs to carry out all types of functions. commercially available ICs of this type can be used as amplifiers, voltage regulators,crowbars,AM receivers,TV circuits,and computer circuits.
However,the monolithic circuits have the following limitations or drawbacks:
(i) Low power rating.since monolithic ICs are of about the size of a discrete small-signal transistor,they typically have a maximum power rating of less than 1 watt.This limits their use to low-power applications.
(ii)poorer isolation between components.
(iii) No possibility of fabrication of inductors.
(iv)small range of values of passive components used in the ICs.
(v)Lack of flexibility in circuits design as for making any variation in the circuit, a new set of marks is required.
2. Thin and Thick Film ICs. These devices are larger than monolithic ICs but smaller than discrete circuits. These ICs can be used when power requirement is comparatively higher.with a thin-or thick-film IC,the passive cmponents like resistors and capacitors are integrated, but the transistors and diodes are connected as discrete components to from a complete circuit.Therefore,commercially available thin and thick-film circuits are combination of integrated and discrete components.
The essential difference between the thin- and thick-film ICs is not their relative thickness but method of deposition of film.Both have similar appearance,properties and general characteristics.
Thin-Film ICs are fabricated by depositing films of conducting material on the surface of a glass or ceramic base. By controlling the width and thickness of the films,and by using different materials selected for their resistivity, resistors and conductors are fabricated.capacitors are produced by sandwiching a film of insulating oxide between two conducting films,Inductors are made by depositing a spiral formation of film. Transistors and diodes can be produced by thin-film technology;but usually tiny discrete components are connected into the crcuit.
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