US Patent 7385444 Class D amplifier

The class D amplifier comprises a voltage control current source circuit for current-converting the voice voltage signal Vsin of the input into two signals with different polarities, two capacitance elements for integration where the electric charges of the each current-converted signal and the feedback signal are stored respectively, two hysteresis comparators for PWM conversion for comparing the potentials of the two capacitance elements for integration and a reference potential Vcom respectively, two output buffers for amplifying the outputs thereof respectively, and two constant current source feedback circuits for feeding back the output thereof respectively.