Feed-Back Active Control for Half-Bridge Class-D audio amplifiers

In this paper is presented a new technique to avoid the distortion generated due to mid point voltage variations on DC-bus of class-D half bridge audio amplifiers. An usual distortion source on class-D amplifier is the bus-pumping effect. Bus-pumping causes characteristic distortion and introduces attenuation on output gain. Due to this effect the amplifier efficiency decreases. By including distortion factors on the Half-Bridge amplifier model a new feed-back active control (FBAC) is implemented. The FBAC minimizes distortion due to mid point DC-Bus voltage variations. Simulation and experimental results confirm the theoretical approach of parameter influence on Bus-Pumping, and the effectiveness of FBAC implemented control. Results show a clear reduction of generated distortion, which allows incremented audio amplifier efficiency.