On-Wafer Coplanar Waveguide Standards for S-Parameter Measurements of Balanced Circuits Up to 40 GHz

The multimode thru-reflect-line (TRL) calibration technique is applied to perform on-wafer mixed-mode scattering-parameter (S-parameter) measurements for differential circuits. This paper describes the first design and realization of a coupled coplanar waveguide (CCPW) calibration kit on a quartz substrate in the ground-signal-ground-signal-ground configuration. CCPW integrated verification elements such as attenuators, and matched and mismatched transmission lines are simulated and measured to validate the design of the multimode TRL calibration kit as well as the calibration algorithm itself. With the advent of four-port vector network analyzers supporting true mode stimulus, at least two approaches are available for mixed-mode S-parameter measurements. The first one is the one-tier measurement using the single-ended stimulus with the multimode TRL calibration technique. The second one relies on the two-tier measurement with a short-open-load-reciprocal thru calibration at the first tier and the multimode TRL calibration at the second tier. From the viewpoint of metrology, the one-tier approach is preferable as it requires fewer standards and connections. The good agreement between simulation and measurement results performed on different verification elements demonstrates the validity of both methods up to 40 GHz.