Design of a reconfigurable load-pull system using novel, digitally controlled, reactances

This paper presents a novel design for a variable impedance system suitable for the characterization of radio frequency (RF) power amplifiers (PAs). The design enables impedance tuning of RF PA load conditions using a passive load-pull technique. The system is capable of presenting a range of load reflection coefficients with a coarse and fine tuning resolution. A manual double-slug tuner provides a coarse tuning stage and the fine tuning stage is comprised of software controlled reactances. Design and measurement of the impedance tuner was carried out at a fundamental frequency of 2.28GHz. Measurements and results of the variable impedance system are presented. Results show good coverage within a reflection coefficient magnitude of 0.8 can be achieved. The prototype design provides a value engineered alternative to high-end passive load-pull commercial systems.