Proposal of Switching Power Amplifier Using Small-Capacity Linear Amplifier and LC Filter

High efficiency and low noise ill Output Voltage and current are required ill audio-video equipment, medical apparatus, and many other applications. This paper proposes a power amplifier in which a PWM inverter is used as the main Circuit. In the proposed power amplifier, a hybrid filter consisting of a simple conventional type I-C filler and it small-capacity linear amplifier is connected to the inverter output. The linear amplifier is inserted in series to the filter capacitor to improve the filtering effect of the LC filter. Switching ripples and I-C resonances are considerably suppressed by controlling the amplifier using (lie proposed method, thus implementing I low-distortion switching power amplifier. The effects of the proposal circuit are verified by simulation and experiments. As a result, the proposed Circuit achieves low noise about THD = 0.68%, in simulation and THD = 1.5% in experiment. (C) 2009 Wiley periodicals, Inc. Electron Comm Jpn, 91(10): 1-10,2008; published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10161