Dear friends
Let me share a different point of view to Class E. I come from the Power
Supply business (switching power supplies), where efficiency is one of the
main design goal (but not always). Please forgive me for all bad
appreciations due to the lack of knowledge on RF PA.
- Efficiency is not only important for the energy saving but it also reduces
mass and volume (less heat sink). It should be indeed the main goal for all
these portable TX/RX (FT817).
- Class E is also a one band amp, but it would be nice if we could change
the tuning elements to adjust them for the different bands (I know, that is
not very easy in this kind of amps).
- I already had the feeling that driving this amps with the output signal of
a normal transceiver is not very easy (impossible?). I have no idea about
this subject, sorry. But I see that the discussion goes into this direction.
- Class E is a step forward of Class D (PWM). Every PS engineer knows that
with MOSFET the switching losses increase with frequency and soft switching
has to be provided to decrease these switching losses. Class E provides this
soft switching means. In the PS business higher frequencies were always
looked after to decrease the size of the reactive elements (L, C and
trafos).
I hope my comments are not completely wrong and I will be looking forward to
see the how the driving discussion goes on. I would appreciate some
solutions on driving this amps directly from a transceiver (please, if
somebody could send to me the references, I would apreciate it very much).
Kind regards,
Stefan
EA5FY
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