[sdiy] OTA performance (was SSM chip reissue)

[Mattias Rickardsson]

On 24 April 2017 at 21:50, Cooper Sloan <mistercooper at gmail.com> wrote:
> Maybe you'll find this interesting if you haven't read it Justin:
> http://www.openmusiclabs.com/files/otadist.pdf
>
> Something I've been wondering about is if this principle applies for our
> OTAs
>
> http://www.linear.com/solutions/5657
>
> I think it could only help tame one type of uncorrelated noise if the
> principle even applies (I'm not that smart), but I dont think I've ever seen
> it done.

It works, yes. The noise sources are uncorrelated and add up less than
the correlated signals do. I sometimes use VCAs in parallel to get a
better SNR, but I've had some indications that it can be tricky with
the capacitive loading on the OP-amp virtual earth, so make sure the
construction is stable before going into mass production. Components
are rarely even close to ideal when it comes to optimizing real-world
scenarios. :-)

/mr