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Q&A Purpose of emitter resistor in a common collector amplifier

In most cases, the common-collector stage (emitter follower) is used as a buffer stage (unity gain). It is, therefore, an independent stage, whose mode of operation should not be determined by the ...

posted 3y ago by LvW‭

Answer
#1: Initial revision by user avatar LvW‭ · 2020-10-19T08:51:18Z (over 3 years ago)
In most cases, the common-collector stage (emitter follower) is used as a buffer stage (unity gain). It is, therefore, an independent stage, whose mode of operation should not be determined by the next stage (which is to be decoupled). 

That means: Even without a connected load this stage should offer a low impedance output voltage.
Therefore, it must have an emitter resistor RE, which allows the desired DC operating point.