Power amplifier linearization method and device based on baseband digital predistortion technology

Abstract

The invention discloses a power amplifier linearization method based on a baseband digital predistortion technology, comprising the following steps of: calculating an instantaneous amplitude Ai and an instantaneous phase theta i of an input baseband signal; respectively searching out a pre-distorted signal amplitude Bi and a pre-distorted phase offset phi i by regarding the instantaneous amplitude Ai as an indexed address of a predistortion lookup table; calculating a pre-distorted signal and then outputting the pre-distorted signal for up-conversion treatment and analogue-to-digital conversion; and finally sending the signal to a power amplifier. During the predistortion, an output signal of the power amplifier is obtained and converted into a baseband feedback signal via a feedback path; and the predistortion lookup table is self-adaptively updated by using the baseband feedback signal and a desired signal. The invention also discloses a predistortion lookup table initialization method matched with the linearization method disclosed by the invention and a linearization device based on the linearization method. The method disclosed in the invention directly adopts signal amplitude as the indexed address of a predistortion lookup table to obtain predistortion signal simply, which not only reduces the treatment relay of the system and the system load, but also reduces the device complexity and the control complexity of the system.

Description

technical field [0001] The present invention relates to communication signal processing, in particular to a linearization method and device for a power amplifier (PA, Power Amplifier) ​​in a communication device. Background technique [0002] In modern communication systems, in order to effectively utilize the radio frequency spectrum bandwidth and ensure a low bit error rate, linear modulation techniques such as QAM, QPSK, OQPSK and π / 4DQPSK are often used. However, the envelope of a signal using these linear modulation techniques changes, and the changing envelope is very sensitive to the nonlinearity of a power amplifier, especially a high power amplifier (HPA, High Power Amplifier), which will lead to nonlinear distortion. Nonlinear distortion can lead to two serious consequences: one is distortion of the receiver signal; the other is out-of-band power. The distortion of the received signal will lead to the decline of system performance, and the purpose of signal transm...

AI Technical Summary

Problems solved by technology

Theoretically speaking, the larger the LUT, the higher the resolution of the predistortion parameters stored in the LUT, and the more it can reflect the detailed changes of the input signal, so the better the effect of the predistortion, the more linear the system is. High; on the contrary, the performance of the system is worse

However, the size of the LUT cannot be infinite; or when a certain system performance is required, that is, the LUT is required to reflect a certain accuracy of the signal, because the value range of the power measurement value is much larger than the value range of the amplitude measurement value, So the complexity required by the power method will be higher

[0008] According to the above analysis, the traditional predistortion technology has the disadvantages of poor performance and high complexity

Especially when hardware is implemented, such as when using DSP (Digital Signal Processor, Digital Signal Processor) or FPGA (Field Programmable Gate Array, Field Programmable Gate Array), the value range of the signal will also directly affect the complexity of the system.

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