How do I perform VNA calibrations with my Pyramid Probe cards? 

Probe cards provide a challenge for two-port calibration. The fixed probe spacing, often with inconveniently oriented ports, makes it difficult to make an ideal thru calibration standard.

For two-port calibrations, a thru standard is required. The general-purpose ISS membrane provides a number of different length thrus, allowing connection of two ports. The electrical behavior may not be that of an ideal thru since it may have a right-angle bend, extra loss, or reactive stubs due to excess length. A custom calibration thru consisting of printed lines on membrane material mounted on a flat slide is available. For longer thrus, it is essential to enter the thru loss into the VNA calibration kit.

Best results will be obtained for two-port Pyramid Probe calibrations using the SOLR (short-open-load-reciprocal thru) calibration available in Cascade Microtech's WinCal VNA Calibration and Measurement software. The SOLR algorithm is not affected by the non-ideal characteristic of the thru, and only a rough estimate of the thru delay is required.