Mobile phone power amplifier linearity and efficiency enhancement using digital predistortion

The new generation mobile communication systems using spectrum efficient linear modulation schemes (QPSK, 8PSK, QAM) need linear power amplifiers in the transmission path to have good ACPR and EVM values. Linearization methods can be used to increase the linearity of the power amplifiers (PA). However, it is not reasonable to use complicated, power consuming and high cost systems. This paper presents a digital predistortion implementation for WCDMA signals using an FPGA (field programmable gate array) as DSP and investigates the application of this system in handsets. The method applied requires minimum change in the conventional transmitter path configuration but considerable PAE improvement can be achieved.