Embedded Bidirectional Buck-Boost Converter in Half Bridge Class-D Audio Amplifier for Suppressing Bus Voltage Pumping

In this paper, a half-bridge class-D audio amplifier (HB-CDAA) system with embedded bidirectional buck-boost converter is proposed. The proposed HB-CDAA system consists of a front-end symmetric bipolar output converter, a bidirectional buck-boost converter and a HB-CDAA. With the help of the embedded bidirectional buck-boost converter, bus voltage pumping on the output of the front-end symmetric bipolar output converter of HB-CDAA can be suppressed. Thus, small ceramic capacitors can be used as bus capacitors to increase power density and to improve audio output quality. Furthermore, ZVS of the embedded bidirectional buck-boost converter can be achieved. The operating principle of the proposed circuit is analyzed and an experimental prototype is built. Experimental results show that ZVS of the embedded bidirectional buck-boost converter is realized, and bus voltage pumping is successfully suppressed with small bus capacitors.