Vector Signaling Codes for Parallel Conductor EMI Reduction
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Solution Overview
Problem
Existing communication interfaces using multiple wire connections face challenges in minimizing electromagnetic interference (EMI) emissions, which are not adequately addressed by conventional signaling methods, leading to non-compliance with international EMI/EMC regulations.
Innovation Solution
The development of specific vector signaling codes that minimize EMI by constructing codewords as polynomials divisible by (x-1)^M, ensuring that summations of current and current squared terms across conductors are zero, thereby reducing the radiated electric field, and using Hadamard matrices to transform initial codes into low EMI codes with improved noise resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional signaling methods are used in parallel wire interfaces, then data transmission can be achieved, but electromagnetic interference (EMI) emissions are not minimized leading to non-compliance with regulations
Solution Approach 1:
The patent applies parameter changes by modifying the signaling code parameters to achieve low EMI characteristics. Specifically, it uses vector signaling codes where codewords are designed with specific mathematical properties (polynomials divisible by (x-1)^M) that control the current distribution across conductors. This changes the electrical parameters of the signaling system to minimize radiated emissions while maintaining data transmission functionality.
Solution Approach 2:
The patent converts the harmful effect of current radiation into a beneficial low-EMI signaling system. By designing codewords with specific properties where the sum of currents and current squared terms are zero, the patent transforms what would normally be harmful radiated emissions into constructive interference patterns that cancel out, turning the EMI problem into a solution.
2Object-affected harmful factors
If vector signaling codes are designed to minimize EMI by constraining current summations, then EMI emissions are reduced, but code design complexity increases
Solution Approach 1:
The patent applies segmentation by breaking down the code design process into manageable components. It segments the problem into: (1) defining the mathematical constraints on current summations, (2) constructing base codes with specific properties, and (3) transforming these codes using Hadamard matrices. This segmentation makes the complex code design process systematic and implementable.
Solution Approach 2:
The patent applies preliminary action by pre-defining the mathematical properties that codewords must satisfy before actual data transmission. The constraints on current summations (sum of currents = 0, sum of current squared terms = 0) are established in advance, and codes are constructed to inherently satisfy these properties. This preliminary constraint definition simplifies the overall design process.
3Reliability
If Hadamard matrices are used to transform initial codes into low EMI codes, then noise resilience is improved, but transformation process complexity increases
Solution Approach 1:
The patent applies universality by using Hadamard matrices that serve multiple functions simultaneously. The same Hadamard transformation that creates the low-EMI code structure also provides noise resilience through its orthogonal properties. This single mathematical operation achieves both EMI minimization and improved signal robustness, reducing the need for separate processing steps.
Data Source
AI summary
Methods are disclosed for creation of vector signaling codes having reduced or minimized electromagnetic emissions when transmitted over multiple conductor communications media such as microstrip channels. Particular code formulation constraints are shown to correlate with physical propagation characteristics leading to beneficial cancellation of far fields from adjacent signal conductors, and the number of such constraints may be chosen to balance EMI characteristics with information encoding capacity in the resulting code.