Mixed mode S-parameters characterization using two-tier calibration method up to 40 GHz

As data rates increase, it is necessary to de-embed the effects of structures between the device-under-test (DUT) and the probe tips to accurately characterize the DUT. This work proposes that once a 4-port device is measured using off-wafer calibration, numerical post-processing of the measured data via a second-tier calibration, such as multiline TRL, can remove end-effects and set the reference planes to the front of DUT. When the mode conversion is weak, the method can be applied separately to the measured differential and common mode S-parameters and it is reduced to the 2-port multiline TRL method. Its effectiveness is demonstrated through numerical validation and measurement data.