Sliding-switching power supply circuit for class-D audio amplifier

The paper presents a robust power supply circuit for class-D audio amplifier especially for multilevel converter. Based on pulse-width-modulation (PWM) buck converter, we develop a sliding-switching technique comprises a loading monitor and a voltage level controller. The loading monitor continuously checks the internal control signal of class-D amplifier to identify whether the loading is light or heavy. The voltage level controller then feedbacks corresponding voltage level to modulate pulse width of control signal in buck converter and adjust supplying current and power delivery. The proposed sliding-switching technique stabilizes the voltage variation of power supply under the situation of alternating light and heavy loading and consequently enhances the performance of total-harmonic-distortion (THD). To demonstrate the practicability, an integrated multilevel class-D amplifier with proposed power supply circuit is implemented under TSMC 0.35µm process. The simulation results show that the total-harmonic-distortion is improved more than 11dB without increasing power consumption of circuit.