Chip-to-Chip Bus Signaling With Spherical Codes for SSO Noise
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Solution Overview
Problem
Current chip-to-chip communication methods face limitations in pin efficiency and noise resilience, particularly in high-speed applications where increasing the number of wires or power consumption leads to noise interference and inefficiencies.
Innovation Solution
The use of spherical codes and permutation modulation codes to map information signals onto a set of physical signals, ensuring that the sum of components across signal lines is zero and maintaining constant power consumption, thereby reducing common-mode and SSO noise, while allowing for efficient encoding and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the number of wires in the communication bus is increased to increase communication speed, then communication speed is improved, but pin efficiency deteriorates and device complexity increases
Solution Approach 1:
The patent transitions from traditional binary signaling (0 and 1) to multi-level signaling using spherical codes where signal points are distributed on a sphere in n-dimensional space. This dimensional transformation allows encoding more information per wire by utilizing the geometric structure of spherical code constellations, achieving higher communication speed without proportionally increasing the number of wires.
Solution Approach 2:
The patent changes the signaling parameters by using permutation modulation codes that map data to specific permutations of spherical code points. By varying the permutation parameters and utilizing the geometric properties of spherical codes with different dimensions and sizes, the system achieves flexible rate adaptation and improved pin efficiency while maintaining high communication speed.
2Power
If transmit power is increased to improve communication performance, then signal strength is improved, but noise and interference increase
Solution Approach 1:
The patent converts the harmful effect of noise and interference into a benefit by using spherical code constellations with optimized minimum distances. The geometric structure of spherical codes provides inherent noise immunity by maximizing the minimum distance between signal points, allowing the system to achieve better error performance without increasing transmit power. The common-mode rejection further converts environmental noise into a non-interfering signal.
Solution Approach 2:
The patent employs forward error correction codes and carefully designed spherical code constellations that provide a margin of protection against noise and interference before the signal is even transmitted. The optimization of minimum distance in the spherical code space creates a cushion against channel impairments, reducing the need for high transmit power while maintaining reliable communication.
3Reliability
If signal swings are increased to improve Gaussian noise resilience, then noise resilience is improved, but power consumption and interference increase
Solution Approach 1:
The patent optimizes the signal constellation parameters by using spherical codes with carefully selected dimensions and minimum distances. Instead of simply increasing signal swings, the system changes the geometric parameters of the constellation to achieve optimal packing density and minimum distance, providing Gaussian noise resilience with moderate power consumption. The permutation modulation allows flexible adaptation of these parameters to match channel conditions.
Solution Approach 2:
The patent moves from one-dimensional amplitude modulation to n-dimensional spherical code modulation. This dimensional change allows the system to achieve better noise resilience by utilizing the geometric structure of high-dimensional space, where the minimum distance between points can be optimized independently of the average power, breaking the direct trade-off between noise resilience and power consumption.
4Reliability
If transmit power is increased to reduce crosstalk noise, then signal strength is improved, but interference to nearby wires increases
Solution Approach 1:
The patent converts the crosstalk interference into a common-mode signal that can be rejected by the differential receiver. By using spherical code modulation with balanced signal structures, the energy that would otherwise cause crosstalk is transformed into a common-mode component that is naturally rejected, achieving crosstalk resilience without increasing interference to nearby wires.
Solution Approach 2:
The patent inverts the traditional approach to crosstalk mitigation. Instead of trying to minimize the differential signal strength to reduce crosstalk, the system uses strong differential signals with optimized spherical code structures that convert crosstalk into common-mode noise. The receiver is designed to reject common-mode signals, effectively inverting the problem so that crosstalk becomes harmless.
Data Source
AI summary
In bus communications methods and apparatus, a first set of physical signals representing the information to be conveyed over the bus is provided, and mapped to a codeword of a spherical code, wherein a codeword is representable as a vector of a plurality of components and the bus uses at least as many signal lines as components of the vector that are used, mapping the codeword to a second set of physical signals, wherein components of the second set of physical signals can have values from a set of component values having at least three distinct values for at least one component, and providing the second set of physical signals for transmission over the data bus in a physical form.