Mobile Phone Power Amplifier Linearity and Efficiency Enhancement Using Digital Predistortion

Abstract

-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.

Effect of the mobile terminal antenna efficiency on the cellular network issues

“…When the antenna efficiency is increased, the smaller amount of RF power is needed at the antenna input terminals in order to maintain equal radiated power. The efficiency of PA is strongly dependent on its output power level and typically decreases at the lower power levels [13], [14]. Thus, 3 dB increased antenna efficiency does not automatically have a direct 3 dB influence on the RF power consumption.…”

Linearization of Power Amplifiers Using the Reverse MM-LINC Technique

“…The model identification in the digital predistortion technique imposes stringent constraints on the digital and analog circuits of the amplification system, which results in increasing the complexity, price, and power consumption of this linearization technique [9]. Indeed, the digital predistortion requires digital preprocessing at a speed of at least five times the signal bandwidth to be able to cancel out the intermodulation products.…”

Evaluation of a digital predistion on FPGA for power amplifier linearization

“…This nonlinear circuit generates the inter-modulation products (IMP) inverse to those produced by the PA and thereby cancelling nonlinearity effect of the PA. There has been a reasonable amount of research carried out in this area [1][2][3][4][5][6][7]. Many versions of the digital pre-distorters have been developed in the past several years, the most popular ones are LUT-based or parametric predistorter with an analytical formulation.…”