A Novel VSWR-Protected and Controllable CMOS Class E Power Amplifier for   Bluetooth Applications
  This paper describes the design of a differential class-E PA for Bluetooth applications in 0.18um CMOS technology with load mismatch protection and power control features. The breakdown induced by load mismatch can be avoided by attenuating the RF power to the final stage during over voltage conditions. Power control is realized by means of "open loop" techniques to regulate the power supply voltage, and a novel controllable bias network with temperature compensated is proposed, which allows a moderate power control slope (dB/V) to be achieved. Post-layout Simulation results show that the level of output power can be controlled in 2dBm steps; especially the output power in every step is quite insensitive to temperature variations. 
Wei Chen and Wei Lin and Shizhen Huang
cs.OH