[sdiy] improved dynamic range diffpair-vca

[Oren Leavitt]

np wrote:
> Hi list, and hello to some old-timers who remember me.. I've been away 
> from the list for several years....
> 
> Is anyone familiar with this circuit here:
> 
> http://www5b.biglobe.ne.jp/~houshu/synth/Vca0302.gif
> 
> It's a long tailed pair with two extra transistors working as diodes. 
> Not the same configuration as the linearization diodes we have in some 
> OTA's. I gave it a try using a CA3046 transistor array, and it just 
> magically works. I can drive the input up to 50mVpp with low distortion. 
> Nearly twice as much as without the extra trannies.
> 
> To me that looks almost like a free meal. Where's the drawback?
> 
> And could someone please shed some light on why these "diodes" work and 
> what they do? They somehow linearize the input for sure, but I have no 
> clue what exactly is going on here.
> 
> Thanks in advance,
>  Nils
> 
> 
>

Thanks Nils, for sharing this.
I have a lot of MAT04s that ought to work fine with this design.
Welcome back!
- Oren