Abstract: A pulse width modulated DC/AC converter includes an input circuit galvanically insulated from an output circuit. The input circuit includes two branches connected in parallel to a pair of input terminals which receive a direct current voltage. Each branch includes an inductor, and a bidirectional switching element which may include a transistor in parallel with a diode. The output circuit has a similar configuration with the addition of two filtering capacitors connected across the output terminals. The converter has a wide range of applications, such as a ringing generator in a telephone system, an emergency supply for a computer system, or as a driving stage for a AC motor.

Abstract: A fully differential CMOS power amplifier having a folded-cascode input stage, an AB class output stage, a first common mode feedback circuit that stabilizes the input stage, and a second common mode feedback circuit that stabilizes the output stage. Each feedback circuit feeds back to an internal node of its particular stage. The power amplifier also includes a power dissipation reduction circuit that shuts down the power amplifier's output first and then the rest of the power amplifier, when the power amplifier is idle for a certain period. This reduction circuit activates the power amplifier in the reverse order.