Re: Re: [sdiy] S&H

[Roman]

Drop caused by SH cap is nothing to worry about in comparison with 
buffer opamp leakage. I'm trying now to make S&H and I must say I 
dropped the idea of using opamp as a buffer long time ago. MOSFET can 
be about 10 times better than low bias opamp. Some of them have gate 
current below 1pA, best I tested - about 1/4pA. It was BSS138 if I 
remember right.

Roman

Tim Ressel <madhun2001 at yahoo.com>:

>John,
>
>Um, I'm not sure. I ain't no S&H expert, I just play
>one on TV. That's why I sed to check out datasheets
>and app notes. I know that there is a way to include
>the SH cap in the feedback path of the opamp to
>prevent droop.
>
>--tr
>
>--- John L Marshall <john.l.marshall at gte.net> wrote:
>> Tim,
>> 
>> Can't the droop be compensated for by a second
>> capacitor in the feedback
>> path of the buffer opamp?
>> 
>> 
>> Take care,
>> John
>>
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