[sdiy] Dual Log/Linear Irwin-Gallo VCA

[Andre Majorel]

On 2009-07-03 00:32 -0700, David G. Dixon wrote:

> I'm very happy to report that my latest module, a dual
> log/linear VCA based on a modified Irwin-Gallo circuit using
> linearized 2164s, is up and running perfectly.  Scope images
> look exactly like my simulations.
>[...]
> I'm totally sold on the 2164.  The Irwin linearization basically
> gives you the equivalent of two "perfect" OTAs -- no fussy
> biasing or trimming, and no need to attenuate the input signal
> to just a few millivolts.  I will definitely be using it in
> place of LM13700 in subsequent designs, and may even go back and
> redesign some OTA-based circuits around it.

Interesting. I wonder how stable it is WRT temperature. The 2164
was designed to pass audio, not to drive VCOs.

-- 
André Majorel <URL:http://www.teaser.fr/~amajorel/>