An amplifier can be considered as a basic electronic circuit. These amplifiers do exist in various types. Based on the operations performed in various modes and the types of configurations used the amplifiers are classified. The basic operation of these devices is to enhance and increase the strength of the applied input signal Common Source Amplifier With voltage divider Bias. Assuming Vt =1.5V for a given NMOS The coupling capacitors C1 (at GATE)and C2(at Drain) which are used to isolate the d.c biasing from the applied ac signal act as short circuits for ac analysis.The effect of bypassing the source resistor can be demonstrated by placing a capacitor in parallel with Rs. By using a switch in series with the bypass capacitor, the feedback path can be controlled. When the capacitor is disconnected, the full source resistance remains in the signal path, producing strong negative feedback and lowering the amplifier gain. When the capacitor is connected, it shorts the AC signal around
Rs.effectively removing the feedback. As a result, the gain increases sharply toward the open-loop value.
