[sdiy] SSM2040 vs CEM3320

[Michael E Caloroso]

One of the other differences of SSM2040 and CEM3320 is that the 3320
includes integrated feedback circuit for VC'd resonance whereas the 2040
does not.  A 2040 designer is free to define the feedback architecture
which is the biggest contributor to the resonance quality and sonority of a
filter network.  With the 3320 (and succeeding SSM/CEM designs) you're
stuck with the feedback architecture on the substrate.

Three problems of the 2040 design is 1) it is VERY sensitive to ESD, 2) the
power rails MUST rise in synchrony on power up, and 3) it has no short
circuit protection on the outputs of the gain cells.

MC

On Thu, Nov 2, 2023 at 10:54 AM René Schmitz <synth at schmitzbits.de> wrote:

> Hi Mark,
>
> Am 02.11.2023 um 14:10 schrieb mark verbos:
> > Don’t you mean
> >
> https://patents.google.com/patent/US4514704A/en?inventor=Douglas+R.+Curtis ?
>
> >
> >
> That is the "who the heck needs buffers?" filter as in CEM3372, and
> possibly others.
>
>
> > I only say that because this is a filter and the one you posted is a
> > “linear/logarithmic analog multiplier”
> > Anyway, cool stuff.
> >
> Hang a few caps to GND in strategic places and you get a filter. The
> description of the cascade of four stages later in the patent is a
> giveaway.
>
>
> Best,
>
>   René
>
>
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