Performance modeling of RF power MOSFETs

This paper presents an analytical study of the RF performance of Si power MOSFET's. Si MOSFET's are rapidly becoming popular in RF applications. Although circuit simulation models have been presented explaining the static performance of these devices, the correlation of device physical parameters with RF performance has not been studied extensively. In this paper, based on the equivalent circuit representation of a power MOSFET, static and large-signal analysis have been carried out to study the RF performance for VDMOSFET and LDMOSFET devices. It has been shown that transconductance compression due to the JFET region leads to degradation of high-power RF performance. It is also shown that LDMOSFET has higher power gain than VDMOS, but steeper degradation with input power. Velocity saturation in the MOS channel and presence of the JFET region are shown to strongly influence the RF performance of the two devices.