A new direct parameter extraction method to determine the small signal equivalent circuit model for deep submicrometer metal oxide semiconductor field effect transistors (MOSFETs) is presented here. This method is a combination of the test structure and analytical methods without reference to numerical optimisation. The main advantage of this method is that the extrinsic resistances, inductances, as well as substrate parasitics can be obtained using a set of exact closed equations based on the cut-off mode S-parameter on wafer measurements. Good agreement is obtained between the simulated and measured results for a 90 nm MOSFET in the frequency range of 50-40 GHz over a wide range of bias points.