Glitches or ringing on the pulse output of the AS3340 and CEM3340

DIY STUFF
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Thanks for the pointer @fredrik.

For the 3340 decoupling, I am not sure if you are agreeing with me or not.
You have to think of the internal zener diode as the voltage regulator for this chip.
VEE is then the negative supply for the rest of the circuit, you want decoupling capacitors between this negative supply and ground and between the positive supply at pin16 and ground.

This is what the #1222 currently has:
3340-decoupling-wrong

And this is what it should be:
3340-decoupling-corrected

I am using 47k for R9, one of the values recommended by Sam in the #1222 VCO documentation for the AS3340.
I see the AS3340 data sheet shows 51k, but their example design is running at +15V, so maybe a value closer to 12/15 x 51k = 40.8k would be more appropriate? It doesn’t seem like it should make much of a difference as that output drives the high input impedance of an opamp, but maybe a lower resistance could reduce the ringing?

EDIT I see that @Caustic is using a 10k resistor in AS3340 VCO /w hard/soft sync, FM modulation and is still seeing some ringing so a smaller resistor doesn’t seem to help.

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