Tuesday, August 25, 2020

mind experiment in amp design part 4

Why would I use the feedback amp design?
It is STABLE. (I emphasize this because someone has stated the opposite)
The input and output Z can be established by selecting the bias resistors.
Why is Z matching important? For an AF amp not so much but signal phasing will effect stability and I could build an oscillator if I don't pay attention to the loading /phasing. The collector signal being 180 degrees out of phase with the input produces degeneration and stability.

It would be good to examine the TD and reflection of Transmission lines. Then consider any conductor carrying a signal is a transmission line. At audio and low RF frequencies we can ignore these principles and get by but as frequency increases we much pay attention to them. 

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