4 wire kelvin test

when measuring very low resistance(miliohm), it is necessary to perform 4 wire test in order to get an accurate reading. However, can opamp(comparator) provide a better accuracy when come to resitance comparison?(ie does opamp able to differentiate a 11miliohm and 10miliohm resistor? provided using the same amount of current supply to the resistor). since the open loop gain of an opamp can reach 1x10^6 which suggest it capable to amplify a very small value to a significant value.
Theoretically, it should working but anyone know does it applicable even in practical?


  • Jeffrey Arulraj
    Jeffrey Arulraj
    Theoretically all is well but not practically

    Whenever you have an Opamp the paramters required to fix it to work with 100% efficiency are really tedious to meet

    No device is 100% efficient But you can approximately differentiate the values of resistors But finding exact value with 741 is not possible in any practical scenario

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