Amplifier Digital Pre-Distortion for HFC Nonlinearity Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Hybrid Fiber-Coaxial (HFC) network amplifiers have low power efficiency, typically around 2%, due to non-linearity issues, which limits the ability to amplify upstream and downstream signals effectively.
Innovation Solution
The implementation of a digital pre-distortion system that characterizes and compensates for the non-linearity of amplifiers and input matching circuitry by generating a distortion correcting signal, allowing the amplifier to be over-driven or reducing its bias, thereby improving power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional amplifier operation is used, then the amplifier can amplify signals, but power efficiency is low (around 2%) due to non-linearity issues
Solution Approach 1:
The system performs preliminary characterization of the amplifier's non-linear behavior through calibration procedures, storing the characteristics in lookup tables. This pre-characterization enables real-time pre-distortion compensation without requiring complex real-time analysis, thereby improving power efficiency while maintaining signal quality.
Solution Approach 2:
The system uses feedback from the amplifier's actual performance to adjust and refine the pre-distortion parameters. By continuously monitoring and adjusting the compensation based on measured non-linearity effects, the system optimizes power efficiency while ensuring reliable signal amplification.
2Use of energy by moving object
If the amplifier is over-driven to improve power efficiency, then power efficiency increases, but distortion increases due to non-linearity
Solution Approach 1:
The system applies preliminary anti-action by pre-distorting the input signal in the opposite direction of the expected non-linear distortion. The pre-distorter modifies the signal before it enters the amplifier, anticipating and counteracting the distortion that would occur during amplification, thereby enabling over-driving without increasing actual distortion.
Solution Approach 2:
The system converts the harmful non-linear distortion into a beneficial effect by characterizing the non-linearity and using it to generate compensating pre-distortion signals. The previously harmful non-linear behavior becomes predictable and controllable, allowing the system to exploit it for improved power efficiency while maintaining signal quality.
3Use of energy by moving object
If digital pre-distortion system is implemented, then power efficiency improves, but device complexity increases
Solution Approach 1:
The system performs complex characterization and calibration procedures in advance, storing results in lookup tables. This preliminary action moves complexity from real-time operation to offline calibration, allowing the real-time system to use simple table lookups and signal processing operations, thereby improving power efficiency without excessive real-time complexity.
Solution Approach 2:
The system introduces a pre-distorter as an intermediary component between the signal source and the amplifier. This intermediary handles the complex non-linearity compensation, allowing the main amplifier to operate more efficiently without requiring complex modifications to its core structure. The pre-distorter acts as a buffer that manages the complexity separately.
Data Source
AI summary
Digital pre-distortion may be provided. First, a characterization for input matching circuitry may be determined. Next, a characterization for non-linearity of an amplifier connected to the input matching circuitry may be determined. Then, a distortion correcting signal may be generated from an input signal based on the determined characterization for the input matching circuitry and the determined characterization for the non-linearity of the amplifier. The generated distortion correcting signal may then be provided to the input matching circuitry.