AW: Compensated Exp generators and VCO's

[Rick Jansen]

In message <2FCD0649 at MSMGATE.M30X.NBG.SCN.DE> Juergen Haible wrote:

> > - Did you compensate for the discharge time in the
> > sawtooth generator and bulk resistance in the exp
> > generator?
> 
> A common way to compensate that effect is a simple resistor
> (or trimpot) in series to the capacitor. If You have a discharge
> time T and a capacitance C, then R=T/C should compensate to 100%.
> Make sure that the comparator input is connected to the current-
> source/trimpot node and not directly to the capacitor.

Hmm... that works of course, but I think it does cost you linearity
of the sawtooth shape itself, as you're now charging the capacitor
via a resistor. The treshold-modification method seems more elegant?

Rick Jansen
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rick at sara.nl   http://www.sara.nl/Rick.Jansen
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