A Novel Four-Port Symmetric Probe Calibration Method for On-Wafer S-Parameter Measurement

This article presents a novel four-port symmetric probe calibration method for on-wafer S-parameter measurement, where by using the symmetric property of the probes, the four-port calibration process is greatly simplified while maintaining a high calibration accuracy. Only four measurements with four different calibration standards are needed in the proposed calibration process, including open, short, load, and thru. Furthermore, only the phase sign is needed for the thru standard rather than its precise S-parameters. The proposed calibration method coupled with an optimization approach is developed to obtain the parasitic parameters of the open, short, and load standards. The proposed method can consider the crosstalk between the probes and move the calibration reference planes to the probe tips. The accuracy of the proposed method is validated in an on-wafer S-parameter measurement system with both ground-signal-signal-ground (GSSG) and ground-signal-ground-signal-ground (GSGSG) probes up to 50 GHz.