A dynamic bias boosting technique for a high efficiency linear HBT dual band power amplifier

A novel dynamic bias boosting technique is proposed, which is composed of a series transistor, a series resistor and a shunt capacitor, and across between the base and the collector of the RF HBT. The new bias boosting is realized and demonstrated through a GaAs HBT three-stage PA under the PCS/WCDMA dual band applications. At a supply voltage of 3.3 V, the PA completely suppresses the gain expansion and exhibits both low distortion and high efficiency, especially at the power back off regions.