Tunable microwave wafer probes

An electronically tuned microwave wafer probe using varactor diodes as tuning elements has been fabricated. This probe can be used for the acquisition of the noise parameters of active devices. A complete set of algorithms has been installed in a simple computer program to allow these measurements to be performed automatically. The probe may be used to generate wafer maps of noise parameters, which are useful for the development of low-noise device processes, and in the monitoring of the performance of low-noise integrated circuits. The authors describe the fabrication of the probe, and detail its use in an automated noise-measurement system.<>