A high performance Si LDMOSFET for RF power amplifiers has been developed for cellular phone applications. This MOSFET achieves low on-state resistance (Ron) (4.0 /spl Omega/ mm) and high transconductance (Gm max) (165 mS/mm). Simultaneously, the MOSFET shows sufficient drain breakdown voltage (>12 V). This is the best performance Si LDMOSFET for RF power amplifiers. An RF power amplifier with the MOSFET accomplishes 60% power-added efficiency (PAE) and 1 W output power (Pout) at 2 GHz operation. The main feature of this MOSFET is the scaled-down structure with very thin gate-bird's beaks (10 nm) for higher Gm and lower parasitic capacitance.