VCA chips

[Martin Czech]

> Yes, I've played with the 2164, and it is a nice chip, but it is
> significantly different from the 2024. The biggest difference being the
> fact that it is controlled exponentially by a voltage rather than
> linearly by a current. Far from a "drop in replacement". 

This was also my impression.
It seems that all linear control VCAs are gone.

Would it be possible to make a VCA with CA3280 in the following manner:
The two otas should match. I can use the linearising diodes,
no need for input attenuator (how much noise comes from the diodes?).
If I set them up in differential mode, ie. one with the signal
at + , the other at - and subtract the output currents, will this
give improoved control feedthrough rejection?
However, the CA3280 data sheet claims lower noise and feedthrough
(then 3080) anyway. Hope I can test this in September.

m.c.