Basic Electronics (3110016)

Question-3b-OR

BE | Semester-1 Winter-2019 | 06-01-2020

Q3) (b)

The process of increasing the signal strength is called as Amplification. This amplification when done without any loss in the components of the signal, it is called Faithful amplification.
Faithful amplification is the process of obtaining complete portions of input signal by increasing the signal strength. This is done when AC signal is applied at its input.
As shown in Fig. - 1, the input signal applied is completely amplified and reproduced without any losses. This can be considered as Faithful Amplification.
The operating point is so chosen that it lies in the active region/middle of the DC load line and it helps in the reproduction of complete signal without any loss.
If the operating point is considered near saturation point, then the amplification will be as Fig. - 2.
When Q point is set near saturation, then negative half cycle of output voltage gets distorted/clipped as shown in Fig. - 2.
If the operation point is considered near cut off point, then the amplification will be as Fig. - 3.
When Q point is set near cut-off, then positive half cycle of output voltage gets distorted/clipped as shown in Fig. - 3.
Hence the placement of operating point is an important factor to achieve faithful amplification. But for the transistor to function properly as an amplifier, its input circuit (i.e., the base-emitter junction) remains forward biased and its output circuit (i.e., collector-base junction) remains reverse biased.