If it is not used, the bias condition of the next stage will be drastically changed due to the shunting effect of R C . The coupling capacitor of value 10 μF is used to couple one stage of amplification to the next stage. signal will flow through R E and cause a voltage drop across it, thereby reducing the output voltage. If this capacitor is not connected in the output circuit then the amplified a.c. (iii) Emitter Bypass Capacitor (C E):Īn emitter bypass capacitor of value 100 μF is used in parallel with R E to provide a low reactance path to the amplified a.c. signal to flow but isolates the signal source from R 2. Otherwise, the signal source resistance will come across R 2 and thus can change the bias. (ii) Input Capacitor (C in):Īn electrolytic capacitor of value 10 μF is used to couple the signal to the base of the transistor. The biasing circuit must establish a proper operating point otherwise a part of the negative half cycle of the signal may be cut off in the output and you will get faithful amplification. The resistances R 1 , R 2 and R E provide biasing and stabilization. The various circuit elements and their functions are described as follows : (i) Biasing Circuit: Practical Circuit of Transistor Amplifier: To achieve faithful amplification in a transistor amplifier, we must use proper associated circuitry with the transistor.Ī practical single stage transistor amplifier circuit is shown in fig. In this way the transistor acts as an amplifier. Thus, a weak signal applied in the base circuit appears in amplified form in the collector circuit. Since the value of load resistance Rc is very high, a large voltage will drop across it. current flows through the the load Rc in the output circuit. signal is applied to the base of the transistor, a small base current starts flowing in the input circuit.ĭue to transistor action, a much larger (β times the base current) a.c. Therefore, such a complex circuit can be conveniently split into several single stages and can be effectively analyzed. However, a practical amplifier consists of a number of single stage amplifiers and hence a complex circuit. When in an amplifier circuit only one transistor is used for amplifying a weak signal, the circuit is known as single stage amplifier.
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