An overview of efficiency enhancements with application to linear handset power amplifiers

A consequence of high spectral efficiency provided by second and third generation cellular systems is the requirement for linear power amplifiers in the transmitter unit of the mobile handset. The battery nature of the mobile phone emphasizes high amplifier efficiency for extending talk time and battery life. This represents an inherent trade-off between amplifier efficiency and linearity. Recent efforts have focused on considering alternative approaches with the goal of improving the efficiency/linearity performance trade-off compared to traditional single-ended Class A/B topologies. Some alternative approaches are examined here.