Abstract: A planar transformer includes a primary winding surrounding a portion of a magnetic core. The primary winding is made up of a bundle of individually insulated conductors (wires) in a bundle, and the bundle is itself separately insulated as a whole. A secondary winding of insulated conductor makes at least one turn around the portion of the core. In one embodiment, the secondary winding is a planar concentric spiral structure with an out-of-plane bridging conductor. Electrical connection tabs may be located adjacent the “ends” of the secondary winding for connection of rectifiers. Series inductors may be connected to each of the tabs and to the direct-current output port of the transformer/rectifier combination, and the conductors of the series inductors may be monolithic with the secondary winding.

Abstract: A full-wave bridge switching power supply includes first and third “serially” connected switches and second and fourth serially connected switches. An output transformer has one end of its primary winding connected to the juncture of the first and third switches and the other end connected to the juncture of the second and fourth switches. The switches are provided with zero-voltage switching signals by way of transformers. In order to avoid the switch-slowing effects of transformer inductance, a subsidiary power supply is associated with each switch. The subsidiary power supplies of the first and third switches are coupled to the control electrodes (gates) of the first and third switches at turn-on, and the subsidiary power supplies of the second and fourth switches are applied during turn-off.