That's a VCA, but there is a VCO with a GATE input:
http://www.emulatorarchive.com/AM/AM20XX/AM2200/am2200.html >maybe that ?
>
>http://www.emulatorarchive.com/AM/AM20XX/AM2000/am2000.html
>
> >
>>> I have never heard of a modular VCO that stops oscillating when a CV
>> is
>>> absent (but then, what do I know anyway?).
>>
>>
>> EMU vco's could function as gated oscillators. It's stalled until it
>> receives a gate, and when the gate is removed the output continues
>> until the waveform completes it's cycle. I don't know of any
>> manufacturers offering this feature in a VCO today.
>> When I was building VCO's awhile ago I experimented with implementing
>> a gate function, but with no success. I probably just need to try
>> harder. Any info on this subject would be greatly appreciated. Feel
> > free to email me privately.
>>