AW: VC pots

[Don Tillman]

   From: Haible_Juergen
   Date: Thu, 26 Oct 95 10:05:00 PDT

FETs:

Also note that there is this linearizing hack: you can mix 1/2 the
audio signal into the control signal at the gate to eliminate the most
pronounced distortion component.  Fans of symmetry will equate this
with setting the ac voltage at the gate to midway between the ac
voltage at the source and drain.

   > I'm pretty sure all special VCA chips are in fact OTAs.

   I don't know the exact definition for "OTA", but I think some
   VCA circuits use a modified 4-quadrant-multiplier structure and
   have the audio signal modulating the *current sources* of
   the two long tailed pairs, routing the *control voltage*
   to the bases of the pairs.

Ah yes, of course!  This arrangement does deserve a seperate catagory
because the circuit configuaration has sufficiently different
characteristics.

  -- Don