Characterization Methods for Millimeter Wave IQ Mixers on the Example of a Planar Star Mixer

This paper reports on the comparison of a conventional and a network-analyzer-based on-wafer measurement setup for millimeter-wave mixer characterization and points out the respective challenges which have to be addressed. Besides conversion gain and port match, the novel measurement approach extends the evaluable parameters to gain and phase imbalance for down-converters and sideband suppression for up-converters. An improved calibration procedure allows to perform independent 2-port calibrations at the different frequency ranges, thus eliminates the systematic errors of conventional setups. The presented monolithic integrated star mixer covers the whole D-band and shows excellent performance in terms of conversion loss and IF bandwidth. To the authors knowledge this is a first time demonstration at millimeter-wave (mmW) frequencies.