16-Term Error Model in Reciprocal Systems

By taking reciprocity of the error network into account, full and accurate calibration of a 16-term error model can be performed using only four two-port calibration standards or termination pairs. Moreover, there is no need for a nonsymmetrical calibration standard that is strictly required in a more conventional five-standard calibration. Commercially available standard substrates can thus be used. Detailed theory of the reciprocal 16-term error model and a new calibration method are presented. Reciprocity assumption is valid in on-wafer and other measurements when two-tier calibration is applied. However, the calibration scheme allows measurement of nonreciprocal devices too. The usefulness of the new method is confirmed by practical wideband on-wafer measurements.