A New Substrate Resistance Model of RF MOSFETs

The substrate resistance of RF MOSFETs significantly affects the small-signal characteristics at high frequency. As a result, the contribution of the substrate resistance cannot be ignored at high frequency [1]-[3]. Although conventinal models with single or three substrate resistors have been shown to be accurate with respect to Re[Y22], they deviate from the measured data with other characteristic such as Re[Y11], Re[Y12]. This means that they focus on the output characteristic rather than exactly describe the MOSFETs physically. The proposed model in this paper consisting of four resistors predicts well the high frequency characteristic of RF MOSFETs including Re[Y11], Re[Y12], and Re[Y22] up to 50 GHz. This extracting method can be achieved by two port Sparameter measurement and does not contain complex optimization process.