  In this work, dynamic load modulation of high power amplifiers using a
varactor-based tunable matching network is presented. The feasibility of
dynamic tuning and efficiency enhancement of this technique is demonstrated
using a modular design approach for two existing high efficiency power
amplifiers (PA), a 7-W class-E, and a 10-W class-J power amplifier PA at 1 GHz.
For this purpose and for each of the PAs, a simple quasi-static inverse model
is developed allowing an efficiency-optimized control of the PA and the
varactor-based tunable matching network. Modulated measurements using a single
carrier WCDMA signal with 11.3 dB peak-to-average ratio (PAR) indicate about 10
to 14 percentage units improvements in the average power-added efficiency (PAE)
for the complete architecture.
