[sdiy] buffer opamp configuration [was: 1/8th inch questions]

[Seb Francis]

Grant Richter wrote:

> >>
> >> Which is why you see a 5 pf cap across every feedback resistor in the LM318
> >> data sheet.
> >
> > Aah, now this is a useful datasheet .. it has exactly the circuit I'm trying
> > to work out .. a S&H cap with unity gain non-inverting opamp.  It has a 10pF
> > cap and a 5K resistor in parallel as the feedback loop.  Split the 5K resistor
> > into a 4K + 1K and you have a current limited output point.
> >
>
> Which is only needed for the 30 Mhz bandwidth of the LM318. Believe me, a
> TL074 will oscillate in the RF range. But it doesn't LIKE to, which an LM318
> does.

I'm using a mixture of MXL1014s and LT1014s .. Maxim wouldn't give me enough for free, and I couldn't find MXLs to buy ;)

I think they have a GBW of about 1MHz (if I read the chart correctly - the gain vs freq chart crosses 0dB at about 1MHz)

I guess with a slower opamp like these, stability is more easily obtained.

Seb