[sdiy] Temperature stable lin-exp converter

[jorgen.bergfors at idg.se]

>If one were to
>take a third transistor and run a constant current
>through it, the Vbe would vary with temperature. You
>could then amplify the Vbe to a useful level and
>polarity, and inject it into the summing node of the
>expo converter input. I think this would give the
>needed temp compensation. What do you think folks?

Does the third tranny need to be matched? Or is it enough that it is
thermally coupled to the other two?

/Jorgen