l7 bjt amplifier
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TRANSCRIPT
In a class A amplifier, the transistor conducts for the full cycle of the input signal (360°) used in low-power applications
The transistor is operated in the active region, between saturation and cutoff saturation is when both junctions are forward biased the transistor is in cutoff when IB = 0
The load line is drawn on the collector curves between saturation and cutoff
BJT Class A AmplifierBJT Class A Amplifier
BJT Class B AmplifiersBJT Class B Amplifiers
When an amplifier is biased such that it operates in the linear region for 180° of the input cycle and is in cutoff for 180°, it is a class B amplifier
A class B amplifier is more efficient than a class A
In order to get a linear reproduction of the input waveform, the class B amplifier is configured in a push-pull arrangement
The transistors in a class B amplifier must be biased above cutoff to eliminate crossover distortion
BJT Class B AmplifiersBJT Class B Amplifiers
Small-Signal Amplifier OperationSmall-Signal Amplifier Operation
In a common-emitter amplifier, the input signal is applied to the base and the output signal is taken from the collector.
Cin is an input coupling capacitor that couples ac but blocks dc.
CE is an emitter bypass capacitor that provides a low-impedance path for ac signals between the emitter terminal and ground.
Small-Signal Amplifier OperationSmall-Signal Amplifier Operation
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Small-Signal Amplifier OperationSmall-Signal Amplifier Operation
Common-Collector AmplifierCommon-Collector Amplifier
The common-collector CC amplifier is used to provide current gain and power gain.
The voltage gain equals approximately one, or unity. The collector is common to both the input and output sides of
the amplifier. The input signal is applied to the base, while the output is
taken from the emitter. The output signal is in phase with the input signal. The CC amplifier is usually referred to as an emitter follower.
Common-Collector AmplifierCommon-Collector Amplifier
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CC amplifier circuit which is also called an emitter follower.
Common Base AmplifierCommon Base Amplifier
The common-base CB amplifier is used less often than the CE or CC amplifiers.
The common-base amplifier provides a high voltage and power gain but the current gain is less than one.
The common-base amplifier has an extremely low input impedance, zin.
The CB amplifier provides some desirable features for operation at higher frequencies.
The CB amplifier is also used in a differential amplifier which is used in linear integrated circuits known as op amps.
Common Base AmplifierCommon Base Amplifier
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The base is grounded. The input signal, Vin, is applied to the emitter and the output is taken from the collector.