[Amps] HV MOSFETs for RF

[Jeff DePolo]

> Does anyone outside of ham radio care about modulation modes 
> that require excellent linearity?

Most definitely - just about any multi-carrier system.  

But let's separate "modulation modes" from the requirement that an
*amplifier* be ideally linear.  

In the non-amateur world (including broadcast, broadband wireless, etc.),
linear and nonlinear distortions in the amplifier, including additional
linear distortions caused by passive filtering that often follows the
amplifier, are corrected for at the input (exciter) via
predistortion/precorrection.  While the amplifier is designed to be linear,
the devices and designs of those non-ham amplifiers, and likewise the
un-corrected performance of those amplifiers, is generally not much
different than the what hams use on the HF/VHF/UHF bands.  In other words,
in the non-amateur world, the *amplifier* isn't orders of magnitude
more-linear, but the transmitting system as a whole is thanks to
predistortion.

The ham world seems to only concentrate on minimizing nonlinear distortions
in the amplifier.  The other side of the coin is we're plagued with
transmitters/transceivers with poor IMD to start with.

						--- Jeff WN3A





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