An automated system for measuring power devices in Ka-band

An active load-pull system is presented for measuring devices from 50-/spl mu/m to 3-mm gatewidth in Ka-band. It can automatically scan the interesting area of the Smith chart. The system protects the tested devices because the impedance is presented at the output of the device only if the gate current is lower than a fixed value. Results are presented at 30 and 38 GHz on a pseudomorphic high electron-mobility transistor (PM-HEMT).