Feedback-coupled high-frequency power oscillator

摘要

A high-frequency power oscillator is built around a power amplifier utilizing semiconductors in a complementary or quasi-complementary stage which operate in a switching mode of operation. The output of the amplifier supplies high-frequency oscillations to a load impedance through an output filter composed of a series-resonant circuit and a parallel-resonant circuit. A feedback driving voltage is obtained from the output filter in a manner providing a first portion of the driving voltage from a voltage present in the parallel-resonant circuit for voltage feedback and a second portion of the driving voltage obtained by current inverse feedback from the current in the series-resonant circuit. These two components of the driving voltage are combined in an addition circuit and supplied to an input of the power amplifier through a pulse modification stage. In the case of high load impedances the operating frequency is as close as possible to the resonant frequency of the parallel resonant circuit and the superimposed current inverse feedback prevents the provision of an operating frequency that would approach the resonant frequency of the series-resonant circuit even when the losses in the series-resonant circuit are small. The ability to use a low-loss series-resonant circuit makes possible increased operation reliability, safety and efficiency.