A 2.4-GHz SiGe HBT power amplifier with bias current controlling circuit

A 2.4-GHz SiGe HBT power amplifier (PA) with a novel bias current controlling circuit has been realized in IBM 0.35-μm SiGe BiCMOS technology, BiCMOS5PAe. The bias circuit switches the quiescent current to make the PA operate in a high or low power mode. Under a single supply voltage of +3.5 V, the two-stage mode-switchable power amplifier provides a PAE improvement up to 56.7% and 19.2% at an output power of 0 and 20 dBm, respectively, with a reduced quiescent current in the low power mode as compared to only operating the PA in the high power mode. The die size is only 1.32 x 1.37 mm2.