CATV Amplifier CFR Circuit for PAPR Reduction and DPD Stability
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Solution Overview
Problem
The transition to DOCSIS 3.1 standards in cable TV amplifiers results in higher signal quality requirements and increased power consumption, making it challenging to maintain improved transmitted signal quality while reducing power consumption, especially since CATV amplifiers operate in a non-linear region and have high peak-to-average power ratio (PAPR) due to 4K QAM OFDM modulation.
Innovation Solution
A crest factor reduction (CFR) system is implemented, including a digital tilt filter, CFR module, digital tilt equalizer, and digital predistortion (DPD) module, which reduces the PAPR of signals and models non-linear components of amplifiers, combined with a digital front-end (DFE) system that uses adaptation engines to update configurations based on feedback, allowing for efficient operation and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DOCSIS 3.1 standards with 4K QAM OFDM modulation are implemented to meet higher data rate demands, then data transmission capability is improved, but peak-to-average power ratio (PAPR) increases and signal quality degrades due to non-linear amplifier operation
Solution Approach 1:
The patent applies preliminary action by performing crest factor reduction (CFR) and digital predistortion (DPD) processing before the signal enters the non-linear amplifier. The CFR module reduces the PAPR of the input signal in advance, and the DPD module pre-compensates for expected non-linear distortions, ensuring that the amplifier operates in a more linear region and maintains signal quality despite the high data rate requirements of DOCSIS 3.1
Solution Approach 2:
The patent introduces intermediary processing modules between the signal source and the amplifier. The CFR module acts as an intermediary to reduce signal peaks, and the DPD module serves as an intermediary to compensate for non-linear effects. These intermediary components enable the system to achieve high data transmission capability while maintaining signal quality by mediating the interaction between the digital signal and the non-linear amplifier
2Productivity
If new components providing high data rates and sophisticated functions are added, then data transmission performance is improved, but power consumption increases
Solution Approach 1:
The patent applies parameter changes by modifying the signal characteristics through CFR processing. By reducing the PAPR parameter of the input signal, the system enables the amplifier to operate at lower power levels while maintaining the same output signal quality. This parameter transformation allows high data transmission performance to be achieved with reduced power consumption from the amplifier and other components
3Use of energy by moving object
If CATV amplifiers operate in non-linear region to reduce power consumption, then power efficiency is improved, but transmitted signal quality degrades
Solution Approach 1:
The patent applies preliminary anti-action by using the DPD module to pre-compensate for the non-linear effects that will occur in the amplifier. The DPD module introduces an inverse non-linear transformation that counteracts the amplifier's non-linearity, allowing the amplifier to operate in a more efficient non-linear region while the overall system maintains linear signal transmission characteristics and high signal quality
Data Source
AI summary
A crest factor reduction (CFR) system includes a digital tilt filter coupled to an input of the CFR system. In some embodiments, the digital tilt filter is configured to receive a system input signal and generate a digital tilt filter output signal at a digital tilt filter output. In some examples, the CFR system further includes a CFR module coupled to the digital tilt filter output, where the CFR module is configured receive the digital tilt filter output signal and perform a CFR process to the digital tilt filter output signal to generate a CFR module output signal at a CFR module output. In addition, the CFR system may include a digital tilt equalizer coupled to the CFR module output, where the digital tilt equalizer is configured to receive the CFR module output signal and generate a system output signal.