Patent ID: 7548112

Claim:
A switch mode power amplifier comprising: a) a field effect transistor comprising a compound semiconductor substrate and having a source terminal, a drain terminal, and a control terminal coupled to a gate contact with a dielectric separating the gate contact and the compound semiconductor substrate, b) a signal input terminal coupled to the control terminal, c) a power terminal conductively coupled to the drain terminal, d) a ground terminal coupled to the source terminal, e) a resonant circuit coupling the drain terminal to an output terminal the resonant circuit configured to provide a bandpass filter that passes a desired output frequency f 0 , and f) a resistance coupling the output terminal to the ground terminal, whereby an input signal to the control terminal controls conduction of the transistor to thereby switch the transistor between an on state and an off state and the drain terminal is coupled to ground when the transistor is conducting in the on state with current from a power source to the drain terminal increasing, and when the transistor is turned off current from the power supply is steered into an internal capacitance of the transistor and causes voltage on the drain terminal to rise to a maximum value and then decrease, the voltage at the drain terminal being coupled to the output terminal through the resonant circuit.