OPA376: noise in inverting amp stage

RIGAS MAKROPOULOS

Part Number: OPA376

Tool/software:

Why when I turn the pot all the way to ground (0% setting) I have interference noise? The noise vanishes as soon as I advance the pot about 2-5%. What am I missing here?

1 month ago

0 RIGAS MAKROPOULOS 1 month ago

Prodigy 20 points

Also, tried to lower the gain increasing the 1k resistor to 4k7 but the issue persists, if not gone worse.

0 Ron Michallick 1 month ago in reply to RIGAS MAKROPOULOS

TI__Guru**** 160901 points

Hello Rigas, welcome to thew TI E2E forums.

Can you share the TI_TINA file and the noise result?

0 Marek Lis 1 month ago in reply to RIGAS MAKROPOULOS

TI__Guru 65700 points

The total output noise of the configuration is very small as it is filtered out by LP output filter - see below.

The circuit is also pretty stable with over 72 degrees phase margin - see below.

Thus, one of the reason for what you see may be the fact that I do not see any supply bypass caps - see below.

If you continue having problems, please show us the scope picture of your "interference noise" so we may be better able to assist you.

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OPA376: noise in inverting amp stage