A practical circuit of a single stage transistor amplifier in CE configuration and using self-biasing is shown in figure below. The resistor R1, R2 and RE from the biasing and stabilization circuit. The biasing circuit must establish a proper operating point otherwise a part of the -ve half cycle of the signal mat be cut off in the output. The Resistor RL connected across the output terminals is called the laod .when a number of stages are employed then RL represents the input resistance for the next stage.
Transistor amplifier practical circuit| Single Stage Transistor Amplifier
An electrolytic capacitor, called the input capacitor Cin of the capacity of about 10microfirade is used to couple the signal to the transistor base. In the absence capacitor, the signal source resistance will come across R2 and thus change the bias . This capacitor allows only AC signal to flow but isolates the signal source from R2. Another capacitor called the emitter bypass capacitor CE, of capacity of about 100microfirade is used in parallel with emitter resistance RE will cause a voltage drop across it which in turn will feedback the input side and reduced the output voltage.(you are reading about Transistor amplifier practical circuit| Single Stage Transistor Amplifier)
For coupling one of stage of amplifier to the next stage another capacitor CC called, the coupling capacitor or blocking capacitor of capacity of about 10 micro5firade is used. Because of its presence, the output across the load resistance RL is free from the collector DC voltage, in this absence RC will come in parallel with the resistor R1 of the biasing network of the next stage and thereby change the biasing condition of the next stage .
Various currents flowing in different branches of the amplifier circuit are indicated in fig
with the application of input signal
Base current(ib)= DC base current due to the biasing circuit+C base current due to ac input signal.(IB+ib)
Collector Current(ic)= Dc collector current due to biasing circuit+ac collector current due to an an input signal (IC+ic)= B(IB+ib)
Emitter Current(ie)= Dc emitter current+ac emitter current due to ac input signal(IE+ie)
Transistor amplifier practical circuit| Single Stage Transistor Amplifier
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| Transistor amplifier practical circuit| Single Stage Transistor Amplifier |
An electrolytic capacitor, called the input capacitor Cin of the capacity of about 10microfirade is used to couple the signal to the transistor base. In the absence capacitor, the signal source resistance will come across R2 and thus change the bias . This capacitor allows only AC signal to flow but isolates the signal source from R2. Another capacitor called the emitter bypass capacitor CE, of capacity of about 100microfirade is used in parallel with emitter resistance RE will cause a voltage drop across it which in turn will feedback the input side and reduced the output voltage.(you are reading about Transistor amplifier practical circuit| Single Stage Transistor Amplifier)
For coupling one of stage of amplifier to the next stage another capacitor CC called, the coupling capacitor or blocking capacitor of capacity of about 10 micro5firade is used. Because of its presence, the output across the load resistance RL is free from the collector DC voltage, in this absence RC will come in parallel with the resistor R1 of the biasing network of the next stage and thereby change the biasing condition of the next stage .
Various currents flowing in different branches of the amplifier circuit are indicated in fig
with the application of input signal
Base current(ib)= DC base current due to the biasing circuit+C base current due to ac input signal.(IB+ib)
Collector Current(ic)= Dc collector current due to biasing circuit+ac collector current due to an an input signal (IC+ic)= B(IB+ib)
Emitter Current(ie)= Dc emitter current+ac emitter current due to ac input signal(IE+ie)
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