An enhanced modulated waveform measurement system for characterization of microwave devices under complex modulated excitations

This paper presents an enhanced modulated waveform measurement system for the robust characterization and optimization of nonlinear microwave devices when driven by broadband multi-tone stimuli. This enhanced system has the ability to present specific, constant broadband impedances, not only at baseband (IF) frequency, but also at RF frequencies, particularly, around the carrier and significant harmonics. Achieving such comprehensive impedance control across wide modulation bandwidths is critical in allowing the 'emulation' of new power amplifier modes and architectures, and the subsequent waveform characterization of devices operating in these complex and often dynamic impedance environments. The capability of the enhanced system is experimentally demonstrated through the measured adjacent channel inter-modulation power behavior of a 10W GaN HEMT biased in class AB and tuned for maximum output peak envelope power (PEP).