Receiver Equalization Using Edge-Sample Pattern Correlation

Solution Overview

Problem

Existing high-speed communication systems face challenges in efficiently compensating for channel-induced distortion due to pattern-dependent attenuation, which requires complex and power-intensive adaptive equalization schemes.

Innovation Solution

The implementation of an adaptive receiver equalization system that reuses clock and data recovery circuitry to optimize equalization, using a pattern mask and equalization logic to adjust amplification factors based on specific data patterns, thereby minimizing timing errors and aligning zero crossings across different data patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If adaptive equalization schemes use sensitive analog circuitry and additional samplers to compensate for channel distortion, then equalization performance is improved, but system complexity, implementation difficulty, and power requirements significantly increase

Engineering Contradiction:

Improveequalization performanceVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the equalization function with existing clock and data recovery circuitry. The same sampler that recovers data also provides samples for equalization measurement, and the equalization control is integrated into the existing recovery logic. This merging eliminates the need for separate equalization circuitry while maintaining adaptive equalization capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The sampler is made multi-functional by using it for both data recovery and equalization measurement. The same hardware component performs multiple functions: recovering the data signal and simultaneously providing samples that are used to detect pattern-dependent distortion and control the equalization filter coefficients.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If adaptive equalization schemes use sensitive analog circuitry and additional samplers to compensate for channel distortion, then equalization performance is improved, but power requirements significantly increase

Engineering Contradiction:

Improveequalization performanceVSAvoidpower requirements

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent combines the equalization function with existing clock and data recovery circuitry. The same sampler that recovers data also provides samples for equalization measurement, and the equalization control is integrated into the existing recovery logic. This merging eliminates the need for separate equalization circuitry while maintaining adaptive equalization capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system uses its own existing resources (the sampler already present for data recovery) to perform equalization measurement and control. Rather than adding dedicated equalization hardware that would consume additional power, the system makes its existing circuitry serve the dual purpose of data recovery and equalization, effectively making the equalization function self-powered through resource reuse.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If equalization parameters are dynamically adjusted to account for channel variations, then compensation for process variations and temperature fluctuations is improved, but system complexity increases

Engineering Contradiction:

Improvecompensation for channel variationsVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements feedback by using the sampler to continuously monitor the received signal quality and detect pattern-dependent distortion. The detected distortion information feeds back to the equalization control logic, which adjusts the equalization filter coefficients in real-time to compensate for channel variations caused by process variations, temperature, and other environmental factors.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The equalization parameters are made dynamic rather than fixed. The system continuously adapts the equalization filter coefficients based on the currently received data pattern, allowing the equalization to respond to changing channel conditions. This dynamic adjustment is achieved by correlating the sampled signal with the incoming data pattern and using the correlation result to control the filter settings.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8665940B2Adaptive equalization using correlation of edge samples with data patterns

Publication Date: 2014.03.04 RAMBUS INC

AI summary

An integrated receiver supports adaptive receive equalization. An incoming bit stream is sampled using edge and data clock signals derived from a reference clock signal. A phase detector determines whether the edge and data clock signals are in phase with the incoming data, while some clock recovery circuitry adjusts the edge and data clock signals as required to match their phases to the incoming data. The receiver employs the edge and data samples used to recover the edge and data clock signals to note the locations of zero crossings for one or more selected data patterns. The pattern or patterns may be selected from among those apt to produce the greatest timing error. Equalization settings may then be adjusted to align the zero crossings of the selected data patterns with the recovered edge clock signal.