On Fri, 08 Oct 2004 11:54:22 -0400, Dave Hall
wrote in :

On Fri, 08 Oct 2004 07:22:54 -0700, Frank Gilliland
wrote:
snip
If Brian appears and brings an open mind, maybe I'll show him how to
use predistortion in the bias regulator to linearize the output. But
that's a big 'if'.

Can you do that for RF amps?


Absolutely. One method is to tap the input signal to a small RF power
transistor with similar nonlinear characteristics and use it to shunt
the input to the final. That method also eliminates the need for a
base resistor and improves bias regulation. Overall, the amp requires
a little more drive power, but the benefits are well worth the costs.
There are other methods that work even better such as high-frequency
OP-amps with nonlinear feedback, inductors with nonlinear saturation
characteristics... just about any part of the circuit can be tailored
to compensate for a nonlinear power device.






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