of the present invention and the scope of the present invention is expressly not limited but expected as specified in the accompanying claims one skilled in the relevant art will recognize however that the invention may be practiced without one or more of the specific details in other instances well known structures materials or operations are not shown or described in order to avoid obscuring aspects of the invention those of ordinary skill in the art will immediately realize that the embodiments of the present invention described herein in the context of methods and schematics are illustrative only and are not intended to be in any way limiting other embodiments of the present invention will readily suggest themselves to such skilled persons having the benefits of this disclosure as it is well known that a power converter having a transformer has a primary and a secondary ground node generally the secondary ground node is connected directly or maybe via a capacitor to the earth ground node as shown in fig1 for a switching power converter all the nodes are jumping from high voltage level to low voltage level and vice versa and the big difference between them is the operating frequency referred to the earth ground for example in fig1 the operating frequency of the node p or s equals to the switching frequency while that of the primary and secondary ground is far less than the switching frequency so the nodes which frequency equals to or is larger than the switching frequency are called the jump nodes or jump point while those less than switching frequency are called the static nodes or static points fig1 shows a flyback converter topology and waveform of main voltage jumps and common mode.