[volt-nuts] HP3458 ADC integrator

[Attila Kinali]

On Fri, 23 Feb 2018 18:48:24 -0000
"David C. Partridge" <david.partridge at perdrix.co.uk> wrote:

> Looking your schematic, I see that you are using LT1225 for both U2 (U111) and U3 (U112)
> 
> Why did you use those rather than LM6361 and AD848?  Was it just because 
> LTSpice didn't have models for them?  It can make a difference ...

Yes. LTSpice doesn't have an LM6361 or AD848. Linear lists the LT1225
as replacement for LM6361, so I thought this was safe. I deemed the AD848
to be close enough.

But as Bruce mentioned, the LT1225 is not unity gain stable, while the
LM6361 is. That might explain the oscillations.

> BTW LM6361 is 550V/mv not .55V (I assume that was a mistake in your post) ... 
> Slew rates seem a bit different at +/- 15V supply as well.

The datasheet I have found (Natsemi Sept 1995) lists 550 V/V = 0.55 V/mV.
Which I think is a bit low, but then, the opamp is old.

			Attila Kinali
-- 
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