Abstract: A class-D amplifier with dual feedback loop scheme has a gain adjusting circuit, a second-order integrator, two comparators, a logic circuit and an output driver. Two differential output terminals of the class-D amplifier are connected to two differential amplifiers of the second-order integrator to construct a second-order feedback loop for offering second order noise shaping, eliminating non-linear components in the class-D amplifier, and also enhancing signal to noise and distortion ratio (SNDR). Further, distortion component existing in the differential signal output from the differential output terminals is amplified by the two differential amplifiers so as to improve the loop gain of the class-D amplifier. The differential signal processed by the two differential amplifiers also can be precisely adjusted.

Abstract: A single-ended class-D amplifier with dual feedback loop scheme has a gain adjusting circuit, a second-order integrator, two comparators, a logic circuit, an output driver and an inverter. The output driver cooperates with the inverter to produce a differential signal. The differential signal is input to the second-order integrator to construct a dual feedback differential loop to eliminate noise of output signals of the class-D amplifier, and offer enhanced signal to noise and distortion ratio (SNDR).

Abstract: A single-ended class-D amplifier with dual feedback loop scheme has a gain adjusting circuit, a second-order integrator, two comparators, a logic circuit, an output driver and an inverter. The output driver cooperates with the inverter to produce a differential signal. The differential signal is input to the second-order integrator to construct a dual feedback differential loop to eliminate noise of output signals of the class-D amplifier, and offer enhanced signal to noise and distortion ratio (SNDR).

Abstract: A class-D amplifier with dual feedback loop scheme has a gain adjusting circuit, a second-order integrator, two comparators, a logic circuit and an output driver. Two differential output terminals of the class-D amplifier are connected to two differential amplifiers of the second-order integrator to construct a second-order feedback loop for offering second order noise shaping, eliminating non-linear components in the class-D amplifier, and also enhancing signal to noise and distortion ratio (SNDR). Further, distortion component existing in the differential signal output from the differential output terminals is amplified by the two differential amplifiers so as to improve the loop gain of the class-D amplifier. The differential signal processed by the two differential amplifiers also can be precisely adjusted.

Abstract: In one embodiment a drive circuit includes two comparators which are adapted to sense kickback voltage generated in an inductive load and conduct two field-effect transistors connected to ground in a very short period of time so as to quickly reduce the kickback voltage to a minimum value. In another embodiment only one comparator is provided.