Lego256
Newbie level 3
op amp gain test
Hi everyone,
I have to test a high gain (100dB+) op amp as accurately as possible so I tried the circuit on page 5 of this course :
**broken link removed**
using a nulling amplifier. It is quite widely used over the internet.
But couldn't make it work.
The high gain of the op amp tested makes the DUT oscillate because of his own noise I think. And as I need a close loop gain as precise as possible, I need well matched resistors and I can't therefore have a huge ratio between them, around 10000 is a maximum. So the level of E0 I look for as output is a few millivolts and a 2V oscillation is... very disturbing...
Anyone has ever tried that kind of test? How would you do it?
Thanks !
Lego
Hi everyone,
I have to test a high gain (100dB+) op amp as accurately as possible so I tried the circuit on page 5 of this course :
**broken link removed**
using a nulling amplifier. It is quite widely used over the internet.
But couldn't make it work.
The high gain of the op amp tested makes the DUT oscillate because of his own noise I think. And as I need a close loop gain as precise as possible, I need well matched resistors and I can't therefore have a huge ratio between them, around 10000 is a maximum. So the level of E0 I look for as output is a few millivolts and a 2V oscillation is... very disturbing...
Anyone has ever tried that kind of test? How would you do it?
Thanks !
Lego