[sdiy] Sample and Hold

[Rutger Vlek]

Hi guys,

Allow me to bump up a not so old thread, as for me it recently became very accurate. I'm trying to finish a very compact S&H and T&H module for my own purposes. 

The requirements are basically
(1) capable of working on CVs (low enough droop to maintain a VCO in tune during 1 minute hold time)
(2) capable of working on audio rate (as sample rate reducer)
(3) low clock bleed through

I explored the options around, and was charmed by the design of Ian Fritz (Super S&H) as well as by the LF398-based one by Rene Schmitz. I've also been considering to draw my own, and was thinking about using a OPA1679 (which I use more often) as it has a typical 10pA input bias current, and I'm trying to decide between the quad MOSFET switches (from the Super S&H) or a plain DG41x series. I have difficulty judging which of these options would best suite my needs, without being overkill, so I hope you can share some experiences and insights? I'm especially interested to know how easily the LF398 is outperformed by other designs. And I'm hoping to learn a bit more about the (dis)advantages of the quad MOSFET switching in the Super S&H over other options (jFET, DG-switch, OTA or even 2164?).

Regards,

Rutger







On 9 jun 2018, at 00:11, Ian Fritz wrote:

> Have another look at my most recent, then:
> http://ijfritz.byethost4.com/sy_cir14_SH.htm
> 
> Ian
> 
> 
> For a synth module, I'd expect a S/H device to work well from as low as 50 uS sampling (of a 20kHz waveform) and as long as a minute hold time (a long sustained CV for a VCO), to cover all possible applications
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