"Robert Morein" wrote in message


Permit me to clarify my comment. When I said MOSFETs are ubiquitous
in power switching applications, I was not referring to audio. Power
converters, inverters, motor drivers, and all other industrial
applications for power control use MOSFETs, except for some rare IGBT
apps.

This has a much to do with the need for high speed at ultrasonic
frequencies, as anything else. Probably more so.

Bipolar is the dominant technology for audio amplification. However,
thermal runaway has never been solved. It cannot be protected against
by feedback or any linear network.

The predominant means for protecting BJTs against thermal runaway is exactly
feedback, feedback of a nonlinear nature.

Practical protective circuits
exist, but they DO fail when pushed to the limit.

Nonsense.

By contrast, a
MOSFET circuit is simply immune to thermal runaway, because the
physical process does not exist in the semiconductor. It is for this
reason that it has been universally adopted for the above mentioned
industrial apps.

That's not right, either. There are tons of BJTs in industrial power
switching apps.