Orthogonal Differential Signaling with Wire-Specific Skew Correction
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Solution Overview
Problem
In multiwire communications systems, differential propagation delays, or skew, among signal wires lead to reduced signal quality due to the constrained time window for capturing valid data words, and existing solutions lack effective methods for unambiguously resolving skew issues at the individual wire path level.
Innovation Solution
A method and apparatus that utilize timing information from detected data signals to correlate with wire input delays, generating wire-specific skew control signals through multi-input comparators (MICs) and adjusting wire-specific skew using these signals, allowing for accurate skew correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiwire parallel communication is used to increase bandwidth, then communication capacity is improved, but differential propagation delays cause signal quality degradation
Solution Approach 1:
The patent segments the skew correction problem into individual wire-specific corrections. Instead of treating all wires uniformly, the system generates separate skew control signals for each wire path, allowing independent adjustment of each wire's timing to compensate for differential propagation delays.
Solution Approach 2:
The system implements feedback by using detected data signal transitions to generate skew measurement signals, which then feed into skew control elements that adjust wire delays. This closed-loop feedback mechanism continuously measures and corrects skew to maintain signal quality.
2Measurement precision
If detailed amplitude and timing detection apparatus are added to each wire input, then skew measurement capability is improved, but power consumption and system complexity increase
Solution Approach 1:
The patent extracts only the essential timing information from received signals - specifically signal transitions - rather than performing full amplitude and timing analysis on each wire. This extraction approach provides sufficient skew measurement capability while avoiding the complexity and power consumption of comprehensive detection apparatus.
Solution Approach 2:
The detected data signals serve multiple functions: they are both the communication payload and the reference for generating skew measurement signals. This multi-functionality eliminates the need for separate measurement apparatus, reducing complexity while maintaining measurement precision.
3Reliability
If trial-and-error delay adjustments are used to tune signal paths, then skew correction capability is improved, but convergence time and system complexity increase
Solution Approach 1:
The system performs preliminary skew measurement using detected signal transitions to generate initial skew control signals before data transmission begins. This preliminary action allows the system to pre-adjust wire delays to optimal values, avoiding time-consuming trial-and-error adjustments during operation.
Solution Approach 2:
The system uses its own received data signals to generate the skew correction information it needs, rather than requiring external calibration equipment or manual adjustment. This self-service approach enables automatic convergence without external intervention, reducing both time and complexity.
Data Source
AI summary
Methods and systems are described for receiving a plurality of signals corresponding to symbols of a codeword on a plurality of wires of a multi-wire bus, and responsively generating a plurality of sub-channel outputs using a plurality of multi-input comparators (MICs) connected to the plurality of wires of the multi-wire bus, generating a plurality of wire-specific skew control signals, each wire-specific skew control signal of the plurality of wire-specific skew control signals generated by combining (i) one or more sub-channel specific skew measurement signals associated with corresponding sub-channel outputs undergoing a transition and (ii) a corresponding wire-specific transition delta, and providing the plurality of wire-specific skew control signals to respective wire-skew control elements to adjust wire-specific skew.