Digital Predistorter Coefficient Mapping Between PSF, OBF, and LUT Models
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Solution Overview
Problem
Existing digital predistortion systems face challenges in efficiently converting model coefficients between different behavior models used in predistorters and adaptation circuits, leading to complexity and cost issues when implementing suitable models for both components.
Innovation Solution
A method and apparatus that utilize a coefficient conversion process to transform model coefficients from one predistorter model to another, allowing for the use of different models in predistorter and adaptation circuits, such as converting between polynomial function-based, orthogonal basis function-based, and look-up table-based models, to optimize circuit complexity and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polynomial function-based model is used in the predistorter, then the linearity and efficiency of the power amplifier are improved, but the device complexity and conversion requirements increase when using a different model in the adaptation circuit
Solution Approach 1:
The patent introduces a coefficient conversion mechanism that acts as an intermediary between the predistorter and adaptation circuit. This converter translates coefficients between different behavior models (PSF, OBF, LUT), allowing each component to use its optimal model without direct compatibility requirements. The conversion process enables independent model selection while maintaining system integration.
Solution Approach 2:
The system separates the predistorter and adaptation circuit into independent modules with distinct model selections. The predistorter can use a PSF model for high linearity, while the adaptation circuit uses a simpler LUT model for efficient training. The coefficient converter bridges these segmented components, allowing each to be optimized independently.
2Adaptability or versatility
If different models are used in predistorter and adaptation circuit, then each component can use its optimal model for its function, but conversion techniques are required which increase complexity and cost
Solution Approach 1:
The coefficient conversion mechanism provides universal compatibility between different behavior models. A single conversion infrastructure supports multiple model types (PSF, OBF, LUT) and can perform conversions in either direction. This universal approach enables flexible model selection while managing complexity through a standardized conversion interface.
3Device complexity
If a look-up table model is used in the predistorter, then the circuit complexity is reduced, but the adaptability and precision of the adaptation process are compromised when using a different model in the adaptation circuit
Solution Approach 1:
The coefficient converter serves as an intermediary that reconciles the different precision requirements of LUT and PSF/OBF models. It translates coefficients from the high-precision adaptation circuit model to the LUT model format, preserving as much precision information as possible while adapting to the target model's constraints.
Data Source
AI summary
Methods and apparatus are disclosed for predistorting an input signal to compensate for non-linear distortions introduced by an electronic device, for example, a power amplifier. The non-linear effects of a power amplifier can be modeled using different behavior models. Coefficients for one behavior model can be converted into coefficients for a different behavior model using a conversion function. A conversion circuit implementing the conversion function can be used in between a predistorter and an adaptation circuit that use different models.