A novel isolated two-phase full bridge topology for VRM applications

In this paper a new isolated full bridge is proposed. Compared with conventional full bridge the new topology can double the output power since its primary side and secondary side operate like two conventional full bridges in parallel and phase shift from each other. But it saves two switches at primary side and it achieves better efficiency. To demonstrate the advantages of the new topology two 48 V input, 1V/70 A output, 1 MHz, power module were built on a 12 layers, 2 oz copper PCB, one with four output inductors, the other with three output inductors. 81.3% &80.8% efficiency are achieved respectively at full load (1 V/70 A) compared with two paralleled FB 80.4% at full load (1 V/70 A) around 1% improvement is achieved. At light load (1 V/20 A), 4% improvement is achieved.