Efficiency improvement techniques at low power levels for linear CDMA and WCDMA power amplifiers

Abstract

Power amplifiers are significant contributors to current consumption within mobile phones resulting in continued focus on design techniques to improve power amplifier efficiency. The techniques presented here use variable bias current and supply voltage, which allow enhanced efficiency at low power levels, and variable load impedance, which provides tradeoffs for optimum linearity and efficiency as a function of power level and battery voltage.