Abstract: Disclosed is an essentially on-chip switching power supply circuit for generating from a single 5 volt power supply high positive and/or low negative voltages of the order of .+-.25 or more. The circuit consists of a pulse generator which alternately activates a positive rail voltage circuit and a negative rail voltage circuit. The positive/negative rail voltage circuit consists of a positive/negative electronic switch in series with a positive/negative voltage generator having an output terminal where the required positive/negative voltage output is generated. The positive/negative voltage generator consists of an inductor and output capacitor coupled together via a rectifying diode.

Abstract: A commutation circuit for thyristors alternately turned ON by pulse width modulation (PWM) for the generation of a fundamental sine wave is characterized by two separate primary windings associated with respective positive and negative thyristors with a common secondary winding at the output, and two commutating networks for the respective poles, each including an auxiliary thyristor for fixed-commutation and the resonant combination of a capacitor and an inductor. The thyristors, the commutating networks, the DC source, and the output transformer have a symmetrical disposition as well as symmetrical commutation steps.