Bonding wire interconnection de-embedding for GaN high electron mobility transistor loadpull measurement with fixture

Test fixtures with high power capacity and an impedance matching network are generally chosen for measurements of high-power gallium nitride high electron mobility transistors. To make interconnection of the test fixtures and devices under test, wire bonding is an effective assembly method. Bonding wires become dominant parasitic elements, especially in the S parameter measurement and loadpull measurement, which should be taken into account and accurately de-embedded for device measurements and modeling. In this paper, test fixtures and through-reflect-line calibration kits are designed to achieve the S parameter measurements of the bonding wire with a vector network analyzer. Equivalent inductances of the bonding wire can be obtained with the electromagnetic simulation model and compact circuit model proposed based on the test fixture. The good agreement of the equivalent inductances extracted with the test fixture and models verified that the way to characterize bonding wire interconnection is effective and accurate. Cree's CGHV1J006D is chosen to take the S parameter measurement for proving the accurate model of the bonding wire. Finally, the equivalent inductance of the 2 mm gate-width transistor is obtained with the electromagnetic model. The drain impedance is accurately calculated after the loadpull measurement with bonding wire effects de-embedded, which matches the loadline theory.