[AMPS] Linearizing Linears, feedback or feedforward
Tue, 26 Sep 2000 21:49:36 -0400
We know that negative feedback in audio amplifiers improves linearity and
reduces distortion. What would it take to improve RF linears with feedback?
In thinking about it for a bit (not enough time, no doubt). It seems that
RF feedback will introduce lots of problems with stability because the
feedback will vary in phase over frequency...producing an oscillator.
Linearizing the envelop might improve things, but it doesn't do anything
about the phase component...might even worsen it.
In the commercial world, broadband, low IMD amplifiers use feed forward
techniques...precompensate the input to produce a clean output. The
principle seems clear but how it applies to a bandswitched amp and how a ham
with just a grid dipper can set it up seems murky.
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