Impact of group delay on the load emulation in multi-tone active envelope load-pull system

摘要

Power amplifiers used in modern day wireless communication systems need to be characterised under complex excitations, into variable load impedances, for the determination of optimum matching conditions. Envelope load-pull technique provides the most realistic possibility for impedance emulation under complex modulation. The system developed for continuous wave modulation, when used under multi-tone excitation, experiences group delay in the feedback loop. This paper explains the impact of group delay on the emulated load and a proposal to overcome the inherent group delay in the feedback loop.