[sdiy] Expo in one chip?

[David G Dixon]

Yes, it's called the V2164, and it is available from Coolaudio in bulk, or
from many retailers (Small Bear, Mammoth, etc).  It is a quad exponential
VCA chip.  One VCA is used to temperature compensate the expo, and another
is used as the actual exponential converter.  It requires an external
summing opamp.  A third VCA can be used as a precision high-frequency
compensation current source, leaving the fourth VCA for another use.  This
is how all Intellijel VCOs (which I designed) are controlled, and they have
a reputation in euro-land for very decent tracking and stability.


  _____  

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Jacob
Watters
Sent: Tuesday, December 26, 2017 12:49 PM
To: SDIY
Subject: [sdiy] Expo in one chip?


Expo conversion is require in almost all VCO, VCF and VCA circuits. Matching
transistors and getting the right tempco resistor to be touching them so
they are the same temp is a pain. 

Has anyone ever made an expo conversion chip that had everything required in
one package? Is it still available?


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