Impact of Broadband Modulation in Active Load-Pull On-Wafer Measurements of GaN HEMTs

This work deals with the impact of broadband modulated excitations on the load-pull characterization of gallium nitride (GaN) on-wafer high-electron-mobility transistors (HEMTs). An experimental assessment is performed by comparing HEMT performance metrics obtained using typical continuous-wave (CW) load-pull characteristics (and their input-statistics weighted version) against the ones directly measured with a wideband active load-pull (WALP) system which allows to set a user-prescribed load profile across arbitrarily-wide measurement bandwidths (BWs). Experimental results across a 100-MHz WALP BW under realistic modulated input excitations at a 6 GHz carrier frequency are reported for a 150nm-gate-length GaN HEMT, highlighting the differences between the various load-pull measurement approaches.