SV: [sdiy] QVCO schemo up

[Ian Fritz]

At 04:07 PM 11/11/05, JH. wrote:

>The stupid diode biasing system of the 13700 forces
>the common mode input voltage to some positive value,
>which means the resistor that feeds the input signal
>draws a hefty bias current, and unbalances the input.
>So you have to set the offset trimmer to an odd value
>even if you'd have a perfect OTA.

Yes. In my big chaos box I had to buffer signals going to the OTAs, since I 
switch in different nonlinearities with different impedances.  Buffering 
was the only way to avoid changes in offset.

   Ian