A fundamental problem of exponential VCOs?

[Ingo Debus]

Hi Juergen,

(my first mail to this list :-) )

what about using a sub-oscillator triggered by the master VCO via
something like a voltage controlled monoflop? The monoflop creates a
delay between the two oscillators, and if the delay is increased
steadily the sub-osc will have a lower frequency than the master. The
same with delay decrease: the sub-osc will have higher frequency. The
rate of delay in(de-)crease determines the frequency difference between
the two oscillators and is independent of the frequency itself. Of
course, delay cannot be in- or decreased all the time. Maybe it is
possible to reset the delay at the very moment when it has reached a
full period of the oscillator frequency (in the case of increasing
delay).
A pitch shifter works similar, but needs a true delay line for audio
signals.

Regards, Ingo