Frequency-Selective Digital Pre-Distortion for Power Amplifier Linearity
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Solution Overview
Problem
Existing wireless communication systems face challenges in optimizing signal transmission at the edge of a spectrum, particularly in suppressing non-linear distortion and enhancing transmit power.
Innovation Solution
The implementation of frequency-selective digital pre-distortion signal generation using a Volterra series model and a shiftable finite impulse response (FIR) filter to adjust Volterra kernel coefficients, generate a compensation signal, and produce a pre-distorted signal that suppresses non-linear distortion at specific frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If transmit power is increased at the edge of a spectrum, then signal strength is improved, but non-linear distortion increases
Solution Approach 1:
The system applies digital pre-distortion to the signal before amplification, anticipating and compensating for the non-linear distortion that will occur in the power amplifier. By pre-modifying the signal characteristics, the system counteracts the expected distortion, allowing high transmit power to be achieved without actually producing harmful distortion in the final output.
Solution Approach 2:
The pre-distortion process introduces an intentional inverse distortion to the signal before amplification. This preliminary anti-action cancels out the non-linear distortion that the power amplifier would otherwise introduce, enabling the system to operate at high power levels while maintaining signal integrity and suppressing harmful distortion.
2Manufacturing precision
If frequency-selective processing is applied, then signal quality at specific bands is improved, but device complexity increases
Solution Approach 1:
The system divides the frequency spectrum into different bands and applies separate pre-distortion processing to each band using a shiftable FIR filter. This segmentation allows frequency-selective optimization of signal quality in specific bands (such as edge bands) without having to process the entire spectrum uniformly, thereby improving signal quality where needed while managing computational complexity through targeted processing.
Data Source
AI summary
This disclosure provides methods, components, devices and systems for signal generation. Some aspects more specifically relate to frequency-selective digital predistortion signal generation. In some examples, the method alters an input signal to produce a frequency-selected linear output signal of a power amplifier. For frequency-selective pre-distortion signal generation, a digital pre-distortion circuit suppresses the non-linear distortion at a specific band using Volterra kernels of a Volterra series model and a shiftable finite impulse response (FIR). The shiftable FIR can filter a particular portion of the signal's frequency, and the Volterra kernels can capture the non-linear memory effects of the input signals and output signals of the power amplifier. Upon refinement of the Volterra kernel coefficients, the Volterra series model can produce a compensation signal. The shiftable FIR can filter the compensation signal to produce a digital pre-distortion signal to input into the power amplifier for transmission.