The improved RF performance of silicon-based technologies over the years and their potential use in telecommunication applications has increased the research in RF modelling of MOS transistors. Especially for analog circuits, accurate RF small signal and large signal transistor models are required. In this paper, we propose an accurate, non-quasi-static, large signal (i.e., nonlinear) RF MOSFET model. Our model consists of a current source and a charge source at the drain terminal and a charge source at the gate terminal. The sources' magnitudes are calculated from the gate-bias and drain-bias dependent elements of the MOSFET equivalent circuit. The MOSFET equivalent circuit elements on itself are extracted from S-parameters at all gate voltages and drain voltages that occur in large signal operation. The accuracy of the equivalent circuit based model is validated by large signal RF measurements using a nonlinear network measurement system. Large signal modelling results using the BSIM3v3 compact model are also presented. Both the equivalent circuit based model and the BSIM3v3 model meet the requirements to describe accurately the RF large signal behaviour of MOS transistors.