The {attached document} is a diagram of a class A output stage. Could some one please tell me how to CHANGE THE CIRCUIT to make it a class B amplifier....
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----------------------------------------------------------Class A amplifiers are biased so that variations in input signal polarities occur within the limits of CUTOFF and SATURATION. In a PNP transistor, for example, if the base becomes positive with respect to the emitter, holes will be repelled at the PN junction and no current can flow in the collector circuit. This condition is known as cutoff. Saturation occurs when the base becomes so negative with respect to the emitter that changes in the signal are not reflected in collector-current flow.
Biasing an amplifier in this manner places the dc operating point between cutoff and saturation and allows collector current to flow during the complete cycle (360 degrees) of the input signal, thus providing an output which is a replica of the input.
Amplifiers biased so that collector current is cut off during one-half of the input signal are classified class B. The dc operating point for this class of amplifier is set up so that base current is zero with no input signal. When a signal is applied, one half cycle will forward bias the base-emitter junction and IC will flow. The other half cycle will reverse bias the base-emitter junction and IC will be cut off. Thus, for class B operation, collector current will flow for approximately 180 degrees (half) of the input signal
BJTs CANT BE CLASS B AMPS.could someone please help me:
1. Give the circuit diagram for a class 'A' output stage
2. Describe how one could change the circuit to make it a class 'B' amplifier
I simply used my knowledge of transistor amplifier classes and manipulated your sketch in Microsoft Paint program to show them.Wow thanks Audioguru, a picture is worth a 1000 words.
Would love to know the source from which you got the above schematic to broaden my knowledge....???
No.Q1} would the attached picture be a class A output stage?
Maybe.if i wanted to change the picture to a class b amplifier, i should replace the collector resistor and bjt by a pair of bjts?
Yes.Q2}On positive swings the voltage across the collector resistor reduces because the collector voltage gets closer to the supply rail?
VRC=VCC-VCollector-VPeak
by Jake Hertz
by Jake Hertz
by Jake Hertz