Selectable-Tap Decision Feedback Equalization for ISI Cancellation

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Solution Overview

Problem

In serial communication systems, such as GPU memory interfaces, decision feedback equalization (DFE) is needed to mitigate noise-induced degradation, particularly intersymbol interference (ISI), which affects the accuracy of information retrieval and requires adaptive noise cancellation based on varying noise patterns.

Innovation Solution

The implementation of a DFE system with selectable taps that generates candidate signals to adjust for predicted noise patterns, selecting the best subset of previous samples to improve signal recovery, allowing for adaptation to different noise conditions and improving system flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If decision feedback equalization is used to mitigate intersymbol interference, then the accuracy of information retrieval is improved, but the device complexity increases

Engineering Contradiction:
Improveaccuracy of information retrievalVSAvoidcomplexity of receiving circuitry
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The DFE system is segmented into distinct functional blocks: a training module for noise pattern detection, a tap selection module for adaptive filter configuration, and a decision feedback equalization module for signal restoration. This segmentation allows each component to perform its specific function efficiently, improving information retrieval accuracy while managing overall system complexity through modular design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic adaptability by allowing the tap selection to vary based on detected noise patterns. The system dynamically adjusts which previous samples are used for noise cancellation, optimizing performance for different communication conditions. This dynamic configuration enables the system to maintain high accuracy across varying channel conditions without requiring a fixed complex structure for all possible scenarios.

Inventive Principle:
Principle #15Dynamics

2Reliability

If DFE system adapts to varying noise conditions, then the reliability of symbol detection is improved, but the device complexity increases

Engineering Contradiction:
Improvereliability of symbol detectionVSAvoidcomplexity of receiving circuitry
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system employs feedback mechanisms where the training module continuously monitors the communication channel for noise patterns and feeds this information back to the tap selection module. This feedback loop enables the DFE system to adapt to varying noise conditions in real-time, improving symbol detection reliability. The feedback-based adaptation avoids the need for complex predetermined configurations for all possible noise scenarios.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the parameter of tap selection based on detected noise patterns. By varying which previous samples are selected for noise cancellation, the system adapts to different communication conditions. This parameter change approach allows the system to maintain high reliability across varying noise environments without requiring a fixed complex structure, as the same hardware can be reconfigured for different conditions.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If multiple previous samples are used for noise cancellation, then the accuracy of information recovery is improved, but the processing complexity increases

Engineering Contradiction:
Improveaccuracy of information recoveryVSAvoidprocessing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of using all available previous samples for noise cancellation, the system selectively uses only the necessary number of samples based on the detected noise pattern. The tap selection module determines the optimal number and combination of previous samples needed for each specific noise condition, avoiding the processing complexity of evaluating all possible sample combinations while maintaining sufficient accuracy for information recovery.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS8837569B2Decision feedback equalization with selectable tap
Publication Date: 2014.09.16 ADVANCED MICRO DEVICES INC
  • US8837569B2 patent drawing
  • US8837569B2 patent drawing
  • US8837569B2 patent drawing

AI summary

A system generates a set of candidate signals based on a received signal, whereby each candidate signal represents an adjustment of the signal for a different amount of potential noise. The system selects one of the candidate signals based on a selected subset of previous samples and the values of the selected subset of samples. The subset of previous samples is selected based on a predicted noise pattern.