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What is the Output from Transistor Amplifier?

What is the Output from Transistor Amplifier?

Answers

- A transistor raises the strength of a weak signal and thus acts as an amplifier. Fig. 4.46 shows the common emitter amplifier. There are two ways of taking output from this transistor connection. The output can be taken either across R_C or across terminals 1 and 2. In either case, the magnitude of output is the same. This is clear from the following discussion:

(i) First method: We can take the output directly by putting a load resistance R_C in the collector circuit
i.e.Output = voltage across R_C = ic R_C ...(i)
This method of taking output from collector load is used only in single stage of amplification.

(ii) Second method. The output can also be taken across terminals 1 and 2 i.e. from collector and emitter end of supply.
Output = Voltage across terminals 1 and 2
= V_CC - i_c R_C
As V_CC is a direct voltage and cannot pass through capacitor CC, therefore, only varying voltage ic R_C will appear across terminals 1 and 2.
- therefore Output = - i_c R_C ...(ii)


- From exps. (i) and (ii), it is clear that magnitude of output is the same whether we take output across collector load or terminals 1 and 2. The minus sign in exp. (ii) simply indicates the phase reversal. The second method of taking output is used in multistages of amplification.

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Wilfykil answered the question on August 15, 2019 at 07:12

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