[Amps] High efficiency broadband designs

[Steve Thompson]

On Thursday 18 December 2003 06:49, Brian Moran wrote:
> The Class-E AM folks are doing some interesting things
> -- Tee the RF input -- one side to an added envelope
> detector, output of this to PWM your power supply to
> the ClassE amp module, other side of the tee to
> through a VGA/limiter, then into the class-E final
> section (phase is preserved, amplitude is constant
> INTO the amplifier),  and you have the basics of an
> EER system; (oh, don't forget the output filters) --
> that's for SSB. For CW, well, just use class E.  With
> the ebb of the high bands, the time may be right for
> encouraging a bunch of experimentation with these
> devices which are more suited (in versions published
> to date) for frequencies below 14MHz. Looks like the
> major class-E issue is tuning of the output network to
> ZVS.
It's many years since I did some class-E work. To get the switching speed 
needed for the really high efficiency needed a small device, which was ok as 
the efficiency was high and dissipation low. That's fine until the load Z 
changes, then you needed a tin hat and flack jacket for protection against 
the flying shrapnel....

Probably different today with newer silicon.

Steve

PS Chris 'DGU - I think I still have some of Vald's custom dual SL644 polar 
loop chips.