De-embedding a device-under-test (DUT) using thru' measurements

A novel approximate method for de-embedding probing structures using just the symmetric thru' line calibration structure is described. The method involves application of a de-convolution technique based on the layer-peeling algorithm to construct an equivalent circuit model using cascaded sections of transmission lines for half of the thru' structure from TDR (time-domain reflectometry) measurements. The non-ideal step input waveform of the TDR, obtained through measuring an open-circuited load, is used to correct for the errors inherent in the layer-peeling algorithm due to the assumed ideal step excitation. A comparison of the results of the proposed method is made with that of TRL and SOLT to validate the method. Also illustrated is the applicability of this technique to SMA (surface-mounted-adapter) based probing structures on printed circuit boards (PCBs), where the standard reference calibration structures are generally not available.