Orthogonal Differential Vector Signaling for Wire-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 shrinking time window for capturing valid data words, and existing solutions are limited by power, complexity, and speed constraints, making it difficult to accurately identify and mitigate timing errors in individual wire paths.
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 effective skew correction in multiwire communications channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If detailed amplitude and timing detection apparatus are incorporated on each individual wire input, then measurement precision of signal variations is improved, but device complexity and power consumption increase beyond practical limits
Solution Approach 1:
The patent segments the detection function by separating timing detection (performed on sub-channel outputs) from individual wire detection. The timing detection is performed collectively on processed sub-channel signals rather than on each wire individually, reducing the complexity of detection apparatus while maintaining measurement precision for timing variations.
Solution Approach 2:
The patent introduces sub-channel outputs as an intermediary between the raw wire inputs and the timing detection apparatus. The multi-input comparators generate sub-channel outputs that represent processed combinations of wire signals, serving as an intermediate representation that simplifies the detection task and reduces the complexity of required detection equipment.
2Reliability
If trial-and-error delay adjustments are performed to tune signal paths, then skew correction effectiveness is improved, but time required for calibration increases
Solution Approach 1:
The patent implements feedback by using detected timing variations from sub-channel outputs to directly control the delay adjustments on individual wires. The system continuously monitors timing variations and adjusts delays in response to detected skew conditions, eliminating the need for time-consuming trial-and-error calibration while maintaining effective skew correction.
Solution Approach 2:
The patent performs preliminary timing detection on sub-channel outputs to identify skew conditions before making delay adjustments. By detecting timing variations in advance and using this information to guide delay adjustments, the system avoids random trial-and-error approaches and reduces calibration time while maintaining correction effectiveness.
3Speed
If the time window for capturing valid data words is reduced due to differential propagation delays, then communication speed increases, but signal quality deteriorates
Solution Approach 1:
The patent applies dynamics by making the sampling timing adaptive rather than fixed. The system dynamically adjusts the sampling window based on detected timing variations in sub-channel outputs, allowing the receiver to maintain optimal signal quality even at higher communication speeds where fixed timing windows would fail due to differential propagation delays.
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.