On power amplifier efficiencies of linearly modulated signals with nonlinear distortion

A power amplifier (PA) is one of the most power consuming analog devices in wireless communications. Precise estimation of the power consumption at the transmitter requires the knowledge of its efficiencies that depend on the signal envelope level to be transmitted. In general, the PA efficiency can be increased by reducing its back-off, but this in turn causes nonlinear distortion. This paper develops a simple analytical approach suitable for examining the trade-off between the PA efficiencies and resulting signal-to-distortion ratio. It can be calculated only from an envelope distribution of a given modulation signal. As an application of the proposed approach, the efficiency improvement of some peak-to-average power ratio reduction schemes proposed for orthogonal frequency-division multiplexing (OFDM) systems is also investigated.