This paper presents a new analysis of RF negative resistance (RFNR) circuits, known as a negative resistance generator. For accurate equation analysis of RFNR, this study examined the effects of the gate resistance and the source parasitic capacitance of the transistor. In addition, the input admittance of the conventional equation was calculated by looking into the source-terminal of the transistor, whereas that of the proposed equation was calculated by examining the gate-terminal of the transistor. The proposed equation analysis is more accurate than that of the conventional analysis, especially for higher frequency range. This paper verify the accuracy of the proposed analysis at high frequency range using the simulation.