Modeling and analysis of stacked depletion-mode NMOS transistors for RF switch applications

Abstract

This paper investigates the use of stacked depletion-mode n-channel MOSFET (D-MOS) for RF switch applications. Compared to the commonly used enhancement-mode MOSFET (E-MOS), the D-MOS transistor offers a significant reduction in on-state resistance (RON) and off-state capacitance (COFF) simultaneously and an excellent figure of merit (RonX Coff) of 134fs (roughly 3X improvement) can be achieved. With the benefit of lower E-field around gate oxide, the D-MOS has higher power handling ability than E-MOS. We analyze a 20dBm SPDT RF switch with a new TCAD modeling methodology, which offer slow insertion loss, high isolation, and high power handling ability.