I. Introduction
The rapid growth of wireless communication product markets has created a huge demand for low-cost, high-efficiency, and good-linearity radio-frequency (RF) power amplifiers. Among power devices, laterally diffused MOS (LDMOS) transistors are the most attractive in cost and potential improvements in performance and integration. LDMOS transistors have been widely used in RF power amplifier modules for a high-frequency range up to 3.8 GHz [1]–[3]. Recently, CMOS device improvements with mechanical strain have produced large IC performance gains [4]–[7]. The strain on the Si channel can be induced by using process technology (e.g., silicon nitride cap, SiGe source/drain, and SiGe buffer layer) and/or by bending the Si wafer directly.