ED104 - Dual VCA

The ED104 is based on Analog device's SSM2164 and was created by Mike Irwin who had it published in EDN magazine. The first stage bends the CV signal in such a way that if you run this output through another identical stage, the next stage's exponential amplification qualities are canceled out, and the amplification becomes linear. This design was later expanded by Phillip Gallo in to a dual lin/log module providing panning capabilities.

http://www.elby-designs.com/contents/en-us/p735_ED104_-_Dual_VCA.html