Hybrid RF and BB Pre-Distortion for Class-AB Amplifier Linearity
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Solution Overview
Problem
Conventional Hybrid Fiber-Coaxial (HFC) network amplifiers, specifically Class-AB amplifiers, suffer from high non-linearity, which limits their power efficiency and effectiveness in broadband networks.
Innovation Solution
The implementation of digital pre-distortion (DPD) in both Radio Frequency (RF) and Base Band (BB) domains to correct the non-linearity of Class-AB amplifiers, combining RF and BB DPD processes to form a hybrid distortion correcting signal that improves power efficiency by compensating for the amplifier's non-linearity and reducing bias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Class-AB amplifiers are used in HFC networks, then power efficiency is improved, but non-linearity increases
Solution Approach 1:
The patent applies digital pre-distortion technology to pre-compensate the input signal before it reaches the Class-AB amplifier. By calculating the inverse of the amplifier's non-linear characteristics and applying this correction in advance, the system eliminates distortion before it occurs, allowing the amplifier to operate in its efficient non-linear region while maintaining linear output.
Solution Approach 2:
The system implements a feedback mechanism where the amplifier's actual output is measured and compared against the expected linear output. This error signal is then used to continuously adjust and refine the pre-distortion coefficients, ensuring optimal compensation for non-linearity while maintaining power efficiency.
2Object-generated harmful factors
If digital pre-distortion is applied to correct non-linearity, then distortion is reduced, but system complexity increases
Solution Approach 1:
The patent segments the pre-distortion process into distinct functional modules: signal analysis module, coefficient calculation module, and signal processing module. This modular approach allows each function to be optimized independently and simplifies implementation while effectively reducing distortion through coordinated operation of the segments.
Data Source
AI summary
Digital pre-distortion may be provided. First, a radio frequency (RF) domain distortion correcting signal and a base band (BB) domain distortion correcting signal may be initialized. Then the RF domain distortion correcting signal may be generated from an input signal. The generated RF domain distortion correcting signal may correspond to an amplifier. Next, the BB domain distortion correcting signal may be generated from the input signal. The generated BB domain distortion correcting signal may correspond to the amplifier. Then the RF domain distortion correcting signal and the BB domain distortion correcting signal may be combined to form a hybrid distortion correcting signal. The hybrid distortion correcting signal may then be provided to input matching circuitry feeding the amplifier.