The transistors are 160 micron gate InP HEMTs provided by Todd Gaier from the Microwave and Lidar Technology Section at the Jet Propulsion Laboratory. In the photo, below, the gate pad is on the left, the drain pad is on the right, and the long pads across the top and bottom are the source.
The transistors were measured two ways. Some transistors were probed directly with a microwave probe station and network analyzer. Other transistors were bump-bonded to simple CPW substrates, and probed including some length of CPW line. The measured scattering matrices of the bump-bonded transistors were mathematically deembedded from CPW line to arrive at measured scattering matrices for bump-bonded transistors.
Marian Pospieszalski's FET model was fit to the measured data. It was found that the differences between the bare transistors and the bump-bonded ones were small.