[sdiy] Expo converter ??

[Ian Fritz]

At 09:41 PM 1/17/2003, harrybissell wrote:
>riddle me this:
>
>What are the advantages/disadvantages  of the NPN/PNP expo converter
>favored by ARP synths... vs the more well known NPN pair and opamp servo
>???
>
>For what parameters are the NPN / PNP matched ???

Harry --

I've always wondered about that too.  Hope you get some good answers.  :-)

The critical part about matched pairs seems to me to be the cancellation of 
the exponential prefactors.  I've never understood how that can be made to 
work well for different transistor types.

Hopefully somebody can tell us!

   Ian