HBT power amplifier with dynamic base biasing for 3G handset applications

In this paper, a performance optimization of a digital signal processing driven and dynamically biased 3G handset's power amplifier technique is proposed, simulated and implemented. This technique uses a new dynamically base biasing heterojunction bipolar transistor which reduces the dc power consumption at low level drive and at the same time compensates the nonlinear distortion at high power drive of the PA in the transmitter of a universal mobile telecommunications system (UMTS) system with a high integrability. With the UMTS system, at low level drive, the dc power reduction is about 60% and at high emission power, the nonlinearity of the PA is corrected to respect the adjacent channel power ratio (ACPR) and error vector magnitude constraints imposed by the UMTS. With our system, the ACPR and efficiency of the power amplifier are improved, respectively, by 5 dB and 8%.