The thru-line-symmetry (TLS) calibration method for on-wafer scattering matrix measurement of four-port networks

The multimode TRL calibration method is known as an approach for the measurement of multi-conductor transmission line devices. The propagation constants of different modes propagating along the multi-conductor transmission line must be different using this method. However, in general multi-port networks, the propagating constants at each port may be equal. We here then present the thru-line symmetry (TLS) calibration method for the calibration of the equal propagation constant case. The calibration equations with the associated calibrators for on-wafer scattering matrix measurement of four-port network are developed. The measured scattering matrix of a branch line coupler using proposed calibration method shows good agreement with simulation. This method can also be extended for the calibration of multi-port networks.