[sdiy] integrator / capacitor leakage

[harrybissell]

imho the weak link is the capacitor...

if the 'smaller' cap allows you to get into a high-quality type
like a polystyrene, I'd go that direction.  Its hard to get large
value, low leakage caps.

Good amplifiers are easier to find.

H^) harry



jhaible at debitel.net wrote:

> When I'm building an integrator for a triangle or sine wave oscillator with an
> amplitude of 20Vpp, I have two options:
>
> a) run the integrator at 20Vpp, or
> b) run the integrator at a lower voltage, and amplify the signal
>    with an extra amp.
>
> Now, for a certain current into the integrator, the integration capacitor
> in case (a) will be much smaller. (Larger voltage to pass in the same time
> at th esame current.)
>
> What is better, in terms of precision / leakage?
>
> At first glance, I'd say leakage is mostly leakage _currents_, so
> it will be the same in both cases.
> At second glance, I'd say if the leakage currents are not entirely
> independent with voltage, case (a) will be worse.
>
> Is this right? Are there other things to consider?
>
> Background: VCO which not only will run from 0.03 Hz to 20kHz,
> but which will also produce very precise waveforms over that
> whole range.
>
> Any ideas / hints welcome.
>
> JH.
>
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