This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM13700: CMRR measurements

Part Number: LM13700

Our customer has a question about the LM13700.
I'm posting the question for the customer:

++++++++++++++++++++++++++++++++++++++++++++++

We would like to measure the CMRR of LM13700.

How does the CMRR be measured exactly?

Please let us know about the test conditions and the test circuits.

++++++++++++++++++++++++++++++++++++++++++++++

Thank you in advance.

Best regards,
Takishin

  • Hello Takishin,

    The LM13700 has a guaranteed minimum common-mode rejection ratio of 80dB which means that we production test this specification. Therefore, we are curious why the customer wants to measure this specification.

    The test involves changing the common-mode voltage of the LM13700 while measuring the change in input offset voltage. This is commonly accomplished by moving the power-supplies with the input's connected to GND. There is often a servo loop to measure the offset voltage.

    CMRR is defined as Delta_Vos / Delta_VCM
  • Hi Collin,

    Thank you for your answer.

    I will report it to the customer.

    Best regards,
    Takishin