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Self-Biased Cathode Follower Output Point

Ardee

Member
2005-11-14 4:00 pm
The output from a self-biased cathode follower is usually taken from the cathode. My gut feeling is that it should be taken from the junction below the bias resistor, where all three resistors meet. Can anyone please explain the advantage of taking the output from the cathode?
 
If you take output from the cathode then the bias resistor is not in the feedback loop, although it does appear in parallel with the output. Maybe you are confused by the grid resistor, which is not for feedback but merely for bias?

As far as feedback is concerned, the output voltage is applied to the cathode while the grid is grounded by whatever feeds it with signal. You can't see the feedback loop because it contains no extra components.
 

Ardee

Member
2005-11-14 4:00 pm
Thanks SY, that does seem to make sense. My thinking was that if the output is taken from below the bias resistor, the resistor just adds to the rp, whereas if the output comes from the cathode, the bias resistor and load resistor form a potential divider for the feedback.

Thanks DF96, My basic understanding of how it works was lacking.
 
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