A Novel Analog Predistortion Technique for LTE Communication Systems

In the advanced communication system, the LTE signals generated through complex modulation techniques have a high peak-to-average-power ratio (PAPR) that pushes the power amplifier (PA) to early saturation. This article presents an analog predistortion technique that helps in linearizing the PA. It divides the input signal into two paths, of which one is passed linearly while the other is passed through a nonlinear path. The proposed technique uses an unequal power divider (UPD) which has the advantage of the ease of selection of the driver amplifier in the nonlinear path. Another advantage of the proposed technique over the conventional method is the design of the distortion generator (DG) that generates the intermodulation components with high strength as compared to that of the conventional methods. The proposed design is tested for an LTE signal with a bandwidth of 20 MHz and a carrier frequency of 1.8 GHz. This achieves a significant improvement in the adjacent-channel-power-ratio (ACPR) with a maximum ACPR improvement of 11.4 dB at 4-dB back-off.