Equalizer Mode Selection Using Phase-Shifted Eye Sampling
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Solution Overview
Problem
Existing equalizers struggle to accurately determine whether they are functioning optimally due to non-vertical edges and shifting transitions in digital signal outputs, making it difficult to select the best equalizing mode for minimizing distortion.
Innovation Solution
A method and device using two sets of sampling pulses with a pre-determined phase shift, establishing observing windows to determine the ratio of transitions between adjacent eyes in an eye diagram, allowing for the selection of the best equalizing mode by advancing the pulses and adjusting the phase shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional single sampling pulse method is used to evaluate equalizer performance, then the evaluation process is simple, but the determination accuracy is poor due to non-vertical edges and shifting transitions forming intervals (eyes) that do not center on sampling pulses
Solution Approach 1:
The sampling process is segmented into multiple independent sampling pulses (first sampling pulses and second sampling pulses) with different phase positions. Each sampling pulse independently samples the equalized signal to form separate eye diagrams, allowing accurate measurement of transition ratios without requiring the sampling pulse to be perfectly centered on the eye opening.
Solution Approach 2:
Multiple sampling pulses are periodically applied to the equalized signal at different phase positions. The periodic sampling captures the signal transitions at various points in the eye diagram cycle, enabling comprehensive evaluation of equalizer performance across the entire eye opening rather than at a single potentially misaligned point.
2Measurement precision
If sampling pulses are positioned to center on eye openings for accurate measurement, then measurement accuracy improves, but the system becomes sensitive to phase misalignment and timing shifts
Solution Approach 1:
Instead of relying on a single centered sampling pulse, the system segments the sampling into multiple pulses distributed across different phase positions. This segmentation eliminates the need for precise phase alignment, as the measurement averages across multiple phase positions, making the system robust against timing shifts and phase errors.
Solution Approach 2:
The system changes the phase parameter of sampling pulses to create multiple sampling instances at different positions within the eye diagram. By varying the phase parameter and measuring transitions at multiple phase points, the system achieves accurate equalizer evaluation without being sensitive to any single phase alignment condition.
3Adaptability or versatility
If multiple equalizing modes are available for selection, then adaptability to different transmission conditions improves, but the complexity of selecting the optimal mode increases
Solution Approach 1:
The system implements feedback by measuring the transition ratio between adjacent eyes in the eye diagram for each equalizing mode and using this measurement to automatically select the optimal mode. The feedback loop compares transition ratios across different modes and selects the mode with the minimal ratio, eliminating the need for complex manual selection or trial-and-error approaches.
Solution Approach 2:
The equalizer system performs self-service by automatically evaluating its own performance across multiple equalizing modes using the multi-phase sampling method and autonomously selecting the optimal mode based on measured transition ratios. This self-service capability eliminates the need for external complex selection mechanisms while maintaining adaptability to different transmission conditions.
Data Source
AI summary
A method and a device for equalizing mode selection are disclosed. The method comprises steps of: providing first sampling pulses in response to an equalized signal; providing second sampling pulses lagging behind the first sampling pulses for a pre-determined phase shift for sampling the equalized signal; establishing a first observing window and a second observing window according to the first sampling pulses and the second sampling pulses, so as to determine whether each of a plurality of equalizing modes is good or bad; and selecting one equalizing mode among the plurality of equalizing modes. The device comprises: a programmable equalizer, having a plurality of equalizing modes, receiving an original signal so as to output an equalized signal; a phase-locked loop, receiving a reference clock signal and a first control signal so as to output first sampling pulses and second sampling pulses; a data slicing device, coupled to the phase-locked loop and the programmable equalizer and receiving the first sampling pulses, the second sampling pulses and the equalized signal so as to output a first slicing signal and a second slicing signal; and a signal processing device, coupled to the data slicing device and receiving the first slicing signal and the second slicing signal so as to output the first control signal and a second control signal; wherein the signal processing device programs the programmable equalizer by using the second control signal so as to select an equalizing mode from the plurality of equalizing modes for the programmable equalizer.