A broadband test fixture for characterizing circuits mounted inside TO-8 package

We present a novel design of two-port test fixture for characterizing infrared (IR) detectors in TO-8 packages with a vector network analyzer (VNA). We characterize the system with a two-tier calibration technique. Ten unknown scattering parameters of our reciprocal fixture are calculated from the second-tier over-determined calibration performed using a special set of tiny short-open-load-thru calibration standards. These standards, built in house on the TO-8 header, were analyzed with an electromagnetic field simulating tool and their characteristics are utilized in the calibration. Having the fixture parameters, we de-embed characteristics of tested IR detectors. Experiments validate high consistency of the de-embedded characteristics for both the standards and test detectors measured up to 3 GHz. This new fixture and de-embedding technique can be easily adapted to characterize broadband circuits mounted in other types of TO packages.