The present disclosure provides a method for testing a semiconductor device. The method includes providing a testing unit and an electronic circuit coupled to the testing unit and applying a first electrical signal to the testing unit. The method includes sweeping a second electrical signal across a range of values, the second electrical signal supplying power to the electronic circuit, wherein the sweeping is performed while a value of the first electrical signal remains the same. The method includes measuring a third electrical signal during the sweeping, the measured third electrical signal having a range of values that each correspond to one of the values of the second electrical signal. The method includes adopting an optimum value of the second electrical signal that yields a minimum value of the third electrical signal. The method includes testing the testing unit while the second electrical signal is set to the optimum value.