A Programmable Impedance Tuner With Finite SWRs for Load-Pull Measurement of Handset Power Amplifiers

A novel coupler/reflection-type electronic impedance tuner is proposed with quantitative analysis. The tuner is divided into a magnitude part and a phase part, and the magnitude and phase of the tuner impedance can be controlled separately just with one design parameter, respectively, thus facilitating programmable control for constant magnitude and uniform phase distribution. The tuner with standing wave ratio (SWR) = 2.5 and 6 was implemented for 3G/4G handset low-band transmitter (Tx) power amplifier (PA) load-pull measurement. The fabricated tuner showed very uniform reflection coefficient distribution with magnitude deviations of less than 0.05/0.08 at SWR = 2.5 / 6 and phase deviations of less than 5 ^°. PA load-pull measurement result using the tuner showed good agreement with a mechanical tuner, thus verifying the practical usefulness of the proposed tuner.