AW: F-V converter and Ring Mod. stuff

[Haible_Juergen#Tel2743]

> on the subject of ring modulators, anyone have schematics for a four
> quadrant multiplier from discrete circuitry (opamps ok)?  I'd like a
> design that can work at DC, too.

I f You really, really want it (do you hate OTA's and balanced
modulators, or what?), You can go this way:
Build two log amp circuits and one exponentiator circuit, using the
common opamp/transistor technique. You will get a 1-quadrant
multiplier this way: a*b = exp(ln(a)+ln(b)). Now You can transform
the 1-quad to a 4-quadrant by using additional opamps and summing
resistor matrix. Well, that would be a discrete + opamp solution.
But I do *not* recommend it !!

JH.