STM32L476 OPAMP CMRR Measurement methods

YLi.12 · ‎2023-02-16

Currently doing academic research.

There are few descriptions in the specification, how to measure CMRR?

FBL · ‎2023-02-22

Hello @Community member

CMRR is a basic electronic measurement and calculated as the ratio of the differential gain to the common-mode gain. You may refer to AN4586 as an example of an implementation to highlight the importance of having very accurate resistors.

Hope this could be an enhancement to guide you on how to calculate CMRR.

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

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View solution in original post

FBL · ‎2023-02-22

Hello @Community member

CMRR is a basic electronic measurement and calculated as the ratio of the differential gain to the common-mode gain. You may refer to AN4586 as an example of an implementation to highlight the importance of having very accurate resistors.

Hope this could be an enhancement to guide you on how to calculate CMRR.

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

I'm out of offce with limited access to my emails.
Happy New Year!

LCE · ‎2023-02-22

The most simple way:

connect the signal output of a single-ended source to both differential inputs
connect the ground of the source to the same ground that the amp-under-test refers to
measure amp output, compare to input

Edit: careful, do not connect any signal generator directly to the controller!

In case of testing a "VCC"-supplied device, it's safest to use the output a single-supply-RRIO-opamp which is also supplied with VCC as a signal source