Four-Port Probe Calibration Using 64-Term Error Model for On-Wafer S-Parameter Measurement of Microwave Circuits Up to 110 GHz

This article presents a novel four-port probe calibration method for on-wafer S-parameter measurement of microwave circuits and, for the first time, realizes measurement verification up to 110 GHz. The method regards the 64 error terms in the four-port probe calibration as an error matrix, which can be solved by a homogeneous equation system using a generalized scatter matrix theory. The calibration algorithm can consider the crosstalk between the probes and improve the calibration accuracy at high frequencies. This method only requires six calibration standards to complete the four-port probe calibration. Only one coupled differential line with a symmetric structure is needed as the Thru, which replaces the traditional U-shape and asymmetric Thru and effectively reduces the number of calibration standards used in the four-port probe calibration. In addition, the method combined with an optimization method accurately and efficiently calculates the parasitic parameters of the calibration standards at high frequencies. The proposed method is validated by three different devices under test (DUTs) up to 110 GHz. Their S-parameters obtained by the proposed method, including all the pure-mode and mode-conversion terms, have high accuracy in magnitude and phase, proving the correctness and convenience of this method.