A method of determining the intrinsic electrical characteristics of a device under test (DUT) includes determining a set of test measurements for a test structure including the device and determining test measurements for a number of de-embedding test structures. Based on the test measurements, DUT measurements are determined using both open-short and three-step de-embedding processes. The DUT measurements are combined to determine an imperfection error, which is used to adjust the calculations of a four-port de-embedding method. The adjusted calculations provide for a more accurate measurement of the parasitic elements in the test structure, thereby improving the determination of the intrinsic electrical characteristics of the device.