The invention is directed to a system for electromagnetic communications that includes a semiconductor die; at least one amplifier on the die to amplify an input signal and generate an output signal; and an active bias control component on the die for adjusting biasing of the amplifier so that the amplifier is operable in a plurality of frequency bands. In one embodiment, a PCS band and W-CDMA power amplifier may be integrated on the same power amplifier die, and different output power requirements may be addressed by the use of an Si DC-DC converter. Such a converter may provide efficiency enhancements to the overall system through the use of dynamic bias control under active power control situations from the network. In addition, the converter may be used in a voltage up-converter state that allows a W-CDMA optimized power amplifier to operate at PCS frequencies and output power levels.