Compensation for geometrical variations in coplanar waveguide probe-tip calibration

We show how coplanar-waveguide probe-tip scattering parameter calibrations performed in one coplanar waveguide conductor geometry may be adjusted for measurement in another. The method models the difference between the two probe-tip-to-coplanar-waveguide transitions as a change in shunt capacitance and applies previously developed techniques for its determination and compensation. Comparison to accurate multiline Thru-Reflect-Line calibrations verifies the accuracy of the method. Differences in both conductor geometry and substrate permittivity are considered in the comparison. The method requires only a single, compact open stub or thru line fabricated on the measurement wafer.