An efficient platform of wireless power delivery through a pair of coupling coils with a fully integrated complementary metal-oxide-semiconductor (CMOS) rectifier is designed and evaluated in this paper. The research is intended for inductively powered energy harvesting application of biomedical sensor network. By making use of high-performance active diodes fulfilling almost ideal switching (zero forward voltage drop) and circuit to be provided with negative resistance, the proposed rectifier circuit is able to achieve a maximum conversion efficiency of more than 90%. This makes it ultra low-loss without any special device requiring additional manufacturing procedures, thereby featuring dramatically reduced production cost. Experimental studies with respect to all aspects of its performance including that used to emulate a truly biological tissue are given as proof of concept.