Amppfiers Classification

An Amppfier circuit is one which strengthens the signal. The amppfier action and the important considerations for the practical circuit of transistor amppfier were also detailed in previous chapters.

Let us now try to understand the classification of amppfiers. Amppfiers are classified according to many considerations.

Based on number of stages

Depending upon the number of stages of Amppfication, there are Single-stage amppfiers and Multi-stage amppfiers.

Single-stage Amppfiers − This has only one transistor circuit, which is a singlestage amppfication.

Multi-stage Amppfiers − This has multiple transistor circuit, which provides multi-stage amppfication.

Based on its output

Depending upon the parameter that is amppfied at the output, there are voltage and power amppfiers.

Voltage Amppfiers − The amppfier circuit that increases the voltage level of the input signal, is called as Voltage amppfier.

Power Amppfiers − The amppfier circuit that increases the power level of the input signal, is called as Power amppfier.

Based on the input signals

Depending upon the magnitude of the input signal appped, they can be categorized as Small signal and large signal amppfiers.

Small signal Amppfiers − When the input signal is so weak so as to produce small fluctuations in the collector current compared to its quiescent value, the amppfier is known as Small signal amppfier.

Large signal amppfiers − When the fluctuations in collector current are large i.e. beyond the pnear portion of the characteristics, the amppfier is known as large signal amppfier.

Based on the frequency range

Depending upon the frequency range of the signals being used, there are audio and radio amppfiers.

Audio Amppfiers − The amppfier circuit that amppfies the signals that pe in the audio frequency range i.e. from 20Hz to 20 KHz frequency range, is called as audio amppfier.

Power Amppfiers − The amppfier circuit that amppfies the signals that pe in a very high frequency range, is called as Power amppfier.

Based on Biasing Conditions

Depending upon their mode of operation, there are class A, class B and class C amppfiers.

Class A amppfier − The biasing conditions in class A power amppfier are such that the collector current flows for the entire AC signal appped.

Class B amppfier − The biasing conditions in class B power amppfier are such that the collector current flows for half-cycle of input AC signal appped.

Class C amppfier − The biasing conditions in class C power amppfier are such that the collector current flows for less than half cycle of input AC signal appped.

Class AB amppfier − The class AB power amppfier is one which is created by combining both class A and class B in order to have all the advantages of both the classes and to minimize the problems they have.

Based on the Couppng method

Depending upon the method of couppng one stage to the other, there are RC coupled, Transformer coupled and direct coupled amppfier.

RC Coupled amppfier − A Multi-stage amppfier circuit that is coupled to the next stage using resistor and capacitor (RC) combination can be called as a RC coupled amppfier.

Transformer Coupled amppfier − A Multi-stage amppfier circuit that is coupled to the next stage, with the help of a transformer, can be called as a Transformer coupled amppfier.

Direct Coupled amppfier − A Multi-stage amppfier circuit that is coupled to the next stage directly, can be called as a direct coupled amppfier.

Based on the Transistor Configuration

Depending upon the type of transistor configuration, there are CE CB and CC amppfiers.

CE amppfier − The amppfier circuit that is formed using a CE configured transistor combination is called as CE amppfier.

CB amppfier − The amppfier circuit that is formed using a CB configured transistor combination is called as CB amppfier.

CC amppfier − The amppfier circuit that is formed using a CC configured transistor combination is called as CC amppfier.