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Does the value of opamp input impedance have direct effect on the amount of noise measured...

Discussion in 'Physics' started by cm64, Oct 8, 2018.

  1. cm64

    cm64 Guest

    Regarding noise added on a signal during transmission i.e. along the long wires between the source and the amplifier, Im wondering whether in a single ended system does the input impedance of the receiver/amplifier(not the gain) has any effect on the amount of noise at the output.

    For example in a single ended system; a 1V DC signal source with an output impedance Rout is coupled to an opamp which has input impedance Rin and and gain of 1 as below:


    The output then will become roughly(neglecting the voltage divider effect) 1V plus the noise picked up due to long non twisted wires along the way. The noise could be due to EMI or ground loop.

    Now where Im stuck is: Is this noise’s magnitude have any relation with the value of Rin or it is only a function of Rout?

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