Sparse Signaling Codes for Low-Power Noise-Resilient Bus Communication
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Solution Overview
Problem
Current chip-to-chip communication systems face challenges in achieving high pin-efficiency, low power consumption, and resilience against noise types such as common-mode noise, SSO noise, and crosstalk, while existing solutions like differential signaling require multiple wires and have high power consumption.
Innovation Solution
The implementation of sparse signaling codes, which use a sparse encoder to map information bits into a permutation of a sparse basis vector, allowing for transmission over fewer active wires with reduced power dissipation and improved noise resilience, eliminating the need for a common reference at transmission and reception points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If differential signaling is used to achieve noise resilience, then reliability is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts and eliminates the common reference voltage requirement from differential signaling by using current-mode logic and differential current signals. This removes the need for precise common-mode voltage control while maintaining noise immunity, thereby reducing device complexity without sacrificing reliability
Solution Approach 2:
The patent changes the signaling parameter from voltage-based differential signaling to current-based differential signaling. This parameter change enables noise resilience through current differential measurement while reducing the need for complex voltage reference management, thus improving reliability without increasing device complexity
2Reliability
If differential signaling is used to achieve noise resilience, then reliability is improved, but power consumption increases
Solution Approach 1:
The patent extracts and eliminates the continuous common-mode voltage maintenance requirement from traditional differential signaling. By using current-mode logic with differential current signals and removing the need for precise common-mode voltage control, the system achieves noise resilience without the continuous power consumption associated with voltage reference management
Solution Approach 2:
The patent changes the signaling parameter from voltage-based to current-based differential signaling. This parameter change enables noise resilience through current differential measurement while reducing power consumption by eliminating the need for high-power voltage reference circuits and reducing the power required for signal switching
3Productivity
If more wires are used to increase bandwidth, then productivity is improved, but pin-efficiency worsens
Solution Approach 1:
The patent merges multiple signal functions into a single differential current pair by using encoding schemes that transmit multiple bits per symbol period. This combining of information channels into fewer physical wires improves pin-efficiency while maintaining high bandwidth productivity through increased data rate per wire
4Device complexity
If fewer wires are used to improve pin-efficiency, then device complexity is reduced, but noise resilience worsens
Solution Approach 1:
The patent changes the signaling parameter from voltage-based to current-based differential signaling with increased signal amplitude. This parameter change enables the use of fewer wires while maintaining noise resilience, as the higher current levels provide better signal-to-noise ratio even with reduced wire count, thus improving pin-efficiency without sacrificing reliability
Data Source
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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 sparse signaling code, wherein a codeword is representable as a vector of a plurality of components, some of which are quiescent components and some of which are non-quiescent components, wherein the number of quiescent components and non-quiescent components meet a sparseness requirement.