US Patent 10063196 Power amplifier

A power amplifier comprising an amplifying element for amplifying a signal input to the amplifier, a matching network for varying the reactance presented to the output of the amplifying element at the fundamental frequency of the input signal, the matching network being switchable between first and second operating configurations, wherein in the first operating configuration, a net inductive reactance is presented to the output at the fundamental frequency and in the second operating configuration, a net capacitive reactance is presented to the output at the fundamental frequency.