FET Common Drain / Source Follower
- details of the common drain or source follower circuit that can be designed using a field effect transistor, FET.
Common drain or source follower is an excellent FET circuit.
The like the transistor emitter follower, the source follower configuration itself provides a high level of buffering and a high input impedance. The actual input resistance of the FET itself is very high as it is a field effect device. This means that the source follower circuit is able to provide excellent performance as a buffer.
The voltage gain is unity, although current gain is high. The input and output signals are in phase.
Diagram of the common drain / source follower FET buffer
Source follower amplifier characteristics summary
The table below gives a summary of the major characteristics of the source follower amplifier.
|Common drain, source follower FET amplifier characteristics|
|Input / output phase relationship||0°|
|Input resistance||Very High|
By Ian Poole
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