Electronically tunable class-E power amplifier

The 20-W class-E power amplifier (PA) described here is electronically tunable from 19 to 31 MHz (ratio 1.67). This PA employs a single RF-power MOSFET and operates from 25 V. The output-tuning network employs fixed inductors and high-voltage MOSFETs for variable capacitors. The PA achieves an efficiency of 61 to 71 percent and has nearly constant output power across the band. It has excellent amplitude-modulation linearity for Kahn-technique transmitters, with two-tone IMDs at -40.4 dBc.