專利摘要：
A built-in input filter forward converter performs to shape an input current to a non-pulsating fashion. Shaping action is obtained by placing two cross-coupled capacitors to a plurality of splitting windings of a power transformer such that the input current will not be interrupted. The cross-coupled capacitors also operate as a lossless snubber by allowing the leakage inductance energy to be stored and recovered during normal operation. Thus significant improvements of reducing harmonic of the input current, input current ripple, and increasing the converter's efficiency are achieved.