Determination of the Coplanar Waveguide Propagation Constant via Non-contact, On-wafer Measurements in WR1.5 Band

We investigate on-wafer measurements made by use of a non-contact probe station in the WR1.5 band (500 GHz to 750 GHz) in order to demonstrate the potential utility of the self-defined, multireflect-thru (MRT) calibration technique. The propagation constant of the on-wafer, coplanar waveguide (CPW) test environment is determined by use of the one-port, reduced reflectometer calibration method. The results of the one-port, calibrated, non-contact measurements are compared to two-port contact measurements calibrated with the multiline thru-reflect-line (TRL) method. The non-contact approach is shown to be promising for self-defined determination of the propagation constant, provided that steps in the CPW center conductor width and CPW gap are introduced into the calibration standards to suppress the coupled-slot-line (CSL) mode.