In this paper ,an efficient parameter extraction method of the small signal equivalent circuit of 40nm MOS transistors on the weak-inversion region are presented by using two-port network analysis method in millimeter wave frequency bands. The equivalent circuit is based on a quasi-static approximation, which includes the complete intrinsic quasi-static MOS model, the series gate resistance, source resistance, drain resistance and a substrate coupling network. Device parameters extraction which divided into parasitic parameter extraction and intrinsic part extraction is performed by Y-parameter analysis on simplifying the equivalent circuit for the way of OPEN and SHORT structures. The extracted results are physically meaningful and can be used to de-embed the extrinsic effects such as the substrate coupling .
