Employing a ground model to accurately characterize electronic devices measured with GSG probes

Traditionally, when measuring an electronic device, the nonideal (non-50 Ω) electrical behavior of the ground-signal-ground probes is removed through calibration. However, this procedure does not allow for an accurate measurement of devices that exhibit an unbalanced flow of electrical currents through the two ground fingers of the probe. We found that a simple interface circuit can be used by a circuit simulator, such as ADS, to reproduce the measurements of devices in which unbalanced ground currents flow in the return paths. A simple experimental method to determine the interface circuit is given.