[sdiy] OTA performance (was SSM chip reissue)

[Mattias Rickardsson]

No, the effect of
2) Gain mismatch being worse at greater attenuation
can go in either direction depending on which pole gets the largest RC in
the lower end, as Richie just pointed out.

/mr


Den 28 apr. 2017 12:09 fm skrev "Tom Wiltshire" <tom at electricdruid.net>:

>
> On 27 Apr 2017, at 22:28, Neil Johnson <neil.johnson71 at gmail.com> wrote:
>
> > Tom,
> >
> >> There are three potential causes we've identified:
> >>
> >> 1) Phase lag
> >
> > No, that causes Q enhancement at the upper end of the frequency range
> > as the cutoff frequency approaches the dominant pole of the
> > op-amps/OTAs and the excess phase (lag) accumulates around the loop.
>
> Ok, strictly "less likely to resonate at lower frequencies" (what I said)
> isn't the same as "more likely to resonate at high frequencies" (what you
> said), but it amounts to much the same thing for practical purposes.
>
> The problem is all of these effects point in the same direction, and we
> don't know which of them is the most important.
>
> Tom
>
>
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