At 14:12 29/01/2002 +0100, Johan wrote:
...Perhaps I am missing something, but as far as I can see,
the waveform *will* be symmetrical if the drive to each totem pole has a
50/50 duty
cycle and the modulation is done only by varying the phase between the
totem pole
drivers 0 - 180 degrees.
Dear Johan, LF Group,
Yes, It will - I hadn't thought of it quite like that before...If you have
4 output devices in a bridge configuration, there are many different ways
of driving them! Of course, any waveform that is symmetrical will have no
even order harmonics.
It would take a little care to implement though; if the drive to only one
of the totem poles was varied in phase, changing the output amplitude would
also change the output phase, introducing up to 90 degrees unwanted
additional phase modulation into the signal. This could be avoided by
shifting the phase of both drive signals by equal and opposite amounts.
Cheers, Jim Moritz
73 de M0BMU
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