Frequency-Selective Adaptive Equalizer for Stable ISI Reduction
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Solution Overview
Problem
Existing adaptive equalizers for minimizing inter-symbol interference (ISI) in communication systems are limited by complexity, high power consumption, stability issues, and dynamic range problems, particularly with long single-frequency signals.
Innovation Solution
An adaptive equalizer circuit with multiple paths, including a through path and equalizer paths, selects the appropriate path based on the relative attenuation of higher-frequency and lower-frequency content in the input signal to equalize signal amplitude effectively, reducing deterministic jitter and channel bandwidth effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback-based adaptive equalization is used, then equalization effectiveness is improved, but stability issues arise and response speed decreases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing equalization coefficients for different channel conditions before actual communication occurs. The system characterizes the channel response in advance and prepares compensation parameters, eliminating the need for real-time feedback during data transmission. This approach maintains stability while achieving effective equalization through pre-planned compensation strategies.
2Reliability
If complex equalizer blocks are used, then equalization performance is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent segments the equalization function into multiple simple parallel paths, each handling a specific frequency range or signal condition. Instead of using one complex equalizer block, the system divides the signal processing into several straightforward stages that can be independently implemented and optimized. This segmentation reduces the complexity of each individual block while maintaining overall equalization performance through coordinated operation of multiple simple stages.
Solution Approach 2:
The patent implements universality by designing equalizer blocks that can handle multiple signal conditions and frequency ranges through configurable parameters. The same hardware structure can be adapted to different channel characteristics by changing control parameters rather than requiring separate specialized blocks for each condition. This multi-functional approach reduces overall device complexity while maintaining high equalization performance across various scenarios.
3Strength
If amplification is applied to compensate for channel loss, then signal amplitude is improved, but dynamic range issues arise due to subsequent attenuation
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting equalization coefficients based on the detected channel characteristics and signal conditions. Instead of fixed amplification that causes dynamic range issues, the system modifies filtering parameters adaptively to compensate for channel loss only where needed. This selective parameter adjustment maintains signal amplitude while avoiding excessive amplification that would create dynamic range problems, achieving loss compensation with controlled signal levels.
Data Source
AI summary
An adaptive equalizer circuit, set forth by way of example and not limitation, includes a plurality of paths receiving an input signal. One or more equalizers are each provided on one of the paths and are operative to equalize signal amplitude. An equalizer selector receives the input signal and is operative to output a selection signal based on higher-frequency content and lower-frequency content of the input signal. The selection signal is operative to select one of the paths to output an output signal that is based on the input signal.