Adaptive biasing for UMTS power amplifiers

An innovative technique for the biasing of power amplifiers (PAs) is presented that allows reduction of the DC power consumption, especially when the PA is operated at mid/low output power, without compromising the linearity at high output power level. The fully integrated adaptive biasing circuit, in 0.5 μm BICMOS technology, senses the operating PA power and adjusts its quiescent current accordingly. The method is applied to a UMTS PA, resulting in a power consumption saving of about 70% when compared to conventional biasing solutions.