[sdiy] Frequency multipliers

David G. Dixon dixon at interchange.ubc.ca
Sat Jun 5 19:47:12 CEST 2010


> > A phase locked loop (4046 etc) with a counter in the feedback path can
> > produce integer multiples of your input frequency, in-phase.  These will
> > be square waves but could be shaped.

...thinking about this a bit more, if square waves were generated with
frequencies in integer multiples of the original, then these could be
integrated directly into triangles, and their amplitudes wouldn't matter
because a differential-pair sine shaper will produce sines of equal
amplitude regardless of the amplitude of incoming triangle, down to a
peak-to-peak amplitude of about 0.5V (although if the incoming peak-to-peak
amplitude is much less than about 1V the minimum THD is somewhat
compromised).  Hence, the various triangles could be boosted to any
convenient amplitude.  However, the master current driving the integrators
would still have to be scaled to the fundamental frequency using a
pitch-to-voltage converter.




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