A Segmented Digital Predistortion Method for Radio Frequency Power Amplifier

Abstract

The invention provides a segmented digital pre-distortion method of a radio frequency power amplifier. According to the segmented digital pre-distortion method of the radio frequency power amplifier, a complete SCPWL segmented function is used for replacing traditional power series to construct a predistorter, and the limits of an existing method are broken through based on mathematical principles. According to the basic method, a characteristic curve of the predistorter is segmented into small sections, the nonlinear strength of each section is reduced, and therefore the order of each section is lowered. The segmented digital pre-distortion method of the radio frequency power amplifier is quite simple to achieve, only needs a simple subtracter, does not need comparative judgment operation, and can be achieved through the method of delaying first and segmentation second, and therefore the module of the entire predistorter can be standardized, has the potential of improving the effect of the predistorter and lowering hardware implementation difficulty.

Description

technical field [0001] The invention relates to a segmented digital pre-distortion method of a radio frequency power amplifier. Background technique [0002] 1. About the digital predistorter [0003] In the fields of radio and television, communication, etc., the signal must be amplified by a power amplifier before transmission. Power amplifiers have natural nonlinear characteristics. If the power of the transmitted signal is large and enters the area where the nonlinearity of the power amplifier is serious, it will have a serious impact on the quality of the transmitted signal. In order to alleviate the influence of nonlinearity, the current practice is to add a pre-distortion module to the digital baseband part of the front end. The characteristics of this module are just opposite to those of the power amplifier, which can compensate the influence caused by the nonlinearity of the power amplifier, thereby improving the quality of the transmitted signal, such as figure 1...

AI Technical Summary

Problems solved by technology

[0005] 2. Existing technologies and their limitations

[0012] 2.1 Problems of Existing Power Series Memory Polynomial Predistorter

Figure 4 The main problem is that the data with small amplitude will be close to zero after high-order power operation, so that the hardware circuit can no longer distinguish these data. Therefore, the order of the existing power series polynomials generally does not exceed 5th order , so the effect of predistortion also has a limit that cannot be broken through

The root cause of this limit originates in the mathematics of the existing technology and thus cannot be solved by technically implemented methods

[0014] The power series polynomial predistorter is suitable for weakly nonlinear power amplifiers, and a high power is required for strong nonlinear power amplifiers, so the power series polynomial predistorter is not applicable

Moreover, new high-efficiency power amplifiers such as envelope tracking (ET) often have special AM-AM curve shapes, and power series polynomial predistorters cannot do anything about nonlinear compensation of these special shapes

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