PWM-based multilevel class-D amplifier with integrated over-current protection system

In this work, we present a multilevel class-D amplifier with integrated over-current protection system based on pulse-width-modulation (PWM). The multilevel technique is composed of a multilevel converter and a time division adder followed by modulator. The modulated signal is fixed into several time divisions and then be integrated and encoded to a set of parallel control signal for multilevel converter. Furthermore, the pulse density adjustment circuit dynamically adjusts the power delivery according to over-current detection. Under the protection scheme, the amplifier is able to completely eliminate audio holes and continue working well without sacrificing total-harmonic-distortion (THD) and power efficiency. The experiment results show that the losses of THD and power efficiency are within 10dB and 2% which significantly improves audio holes effect.