We propose a method to determine the reference impedance of the TRA calibration technique for vector network analysers. This method was developed within the framework of our activity on traceability of on-wafer S parameters measurements. Starting from a modified TRA calibration procedure, we demonstrate the possibility to determine the calibration reference impedance, and leading to a significant reduction of the measurement uncertainties. In comparison with results obtained using the reference multiline TRL calibration technique, the results that we obtain show the efficiency of the present method.

Key words

vector network analyser
S parameters
on-wafer measurements
TRA calibration