Abstract: An active isolation switch according to this invention includes a field effect transistor (FET), a first bi-polar transistor and a second bi-polar transistor, and an emitter bias resistor. The FET is formed with a source, a gate, and a drain. The first bi-polar transistor is formed with a first emitter, a first base, and a first collector; the first emitter is connected to the source and the first collector is connected to the gate. The second bi-polar transistor is formed with a second emitter, a second base, and a second collector, the second base is connected to the first base, and the second collector is connected to the drain. The emitter bias resistor is formed with a first terminal and a second terminal; the first terminal is connected to the emitter of the second bi-polar transistor and the second terminal is connected to the emitter of the first bi-polar transistor.

Abstract: The commutator for a bridgeless PFC circuit is characterized in that a synchronous half-wave rectifier is connected between a bridgeless PFC boost circuit and an AC power source and is coupled to the two terminals of the AC power source. The synchronous half-wave rectifier contains a first synchronous transistor, a second synchronous transistor, and a control circuit.

Abstract: The power supply comprises a bridge rectifier connected to an AC source; a boost converter series-connected to the bridge rectifier comprising an inductance coil; a filter capacitor series-connected to the boost converter; a DC/DC converter connected to a load; a hold-up-time enhancer connected to and positioned between the filter capacitor and the DC/DC converter; and a virtual by-pass system parallel-connected to the hold-up-time enhancer comprising an induction coil inductively coupled to the inductance coil of the boost converter. As such, voltage is induced on the induction coil by the inductance coil in the boost converter and the virtual by-pass system parallel-connected to the hold-up-time enhancer is thereby turned on and off.

Abstract: The commutator for a bridgeless PFC circuit is characterized in that a synchronous half-wave rectifier is connected between a bridgeless PFC boost circuit and an AC power source and is coupled to the two terminals of the AC power source. The synchronous half-wave rectifier contains a first synchronous transistor, a second synchronous transistor, and a control circuit.

Abstract: The power supply comprises a bridge rectifier connected to an AC source; a boost converter series-connected to the bridge rectifier comprising an inductance coil; a filter capacitor series-connected to the boost converter; a DC/DC converter connected to a load; a hold-up-time enhancer connected to and positioned between the filter capacitor and the DC/DC converter; and a virtual by-pass system parallel-connected to the hold-up-time enhancer comprising an induction coil inductively coupled to the inductance coil of the boost converter. As such, voltage is induced on the induction coil by the inductance coil in the boost converter and the virtual by-pass system parallel-connected to the hold-up-time enhancer is thereby turned on and off.