A high efficiency switch-mode sine wave oscillator-power amplifier

A type of oscillator/power amplifier circuit with the advantages of high efficiency and simplicity over commonly used circuits is presented. The circuit load is an LC loop connected serially, instead of in parallel, with the output so that no step-up transformer is needed. Because the LC loop serves as both the load and the oscillation resonance component, the circuit oscillates at the resonance frequency of the LC loop. The circuit works in switch mode and changes its state when the output current crosses zero; this yields high efficiency. After introducing the circuit principles and calculations, some problems which will arise at high frequency and the ways to solve them are discussed. An experimental implementation of the circuit as well as suggestions for the usage of this type the circuit are also given.<>