High-Speed GRS Signaling Over PCB Substrates Without Differential Pairs

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Solution Overview

Problem

Conventional communication systems face increased overhead, reduced performance, and limited bandwidth due to software-managed memory coherence protocols and the use of differential signaling and encoding schemes, which consume additional resources and reduce bandwidth.

Innovation Solution

Implementing a ground referenced signaling (GRS) link between devices that uses similar currents for different logic states, eliminating the need for differential signaling and encoding, thereby reducing noise and allowing for hardware-managed memory coherence protocols.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If differential signaling and encoding schemes are used, then noise is reduced, but bandwidth is reduced and power consumption increases

Engineering Contradiction:

Improvenoise reductionVSAvoidbandwidth

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the signaling parameter from differential voltage to ground-referenced voltage levels. By using a first voltage level (e.g., 0V) for first logic states and a second voltage level (e.g., positive voltage) for second logic states, both referenced to ground, the system achieves noise immunity without requiring differential pairs, thereby increasing bandwidth while maintaining reliability

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If software manages memory coherence protocols, then system flexibility is maintained, but overhead increases and performance decreases

Engineering Contradiction:

Improvesystem flexibilityVSAvoidperformance

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent replaces the software-based memory coherence management with a hardware-managed protocol. By implementing coherence control logic in hardware, the system eliminates software overhead and processing delays while maintaining the necessary adaptability for multi-core and multi-processor systems, thereby improving performance without sacrificing flexibility

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If differential signaling is used, then signal integrity is improved, but the number of traces and balls on PCB increases

Engineering Contradiction:

Improvesignal integrityVSAvoidPCB area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent extracts the ground reference from being just a return path and makes it the explicit reference for voltage levels. By using ground-referenced signaling where both logic states are measured against ground rather than using differential pairs, the system maintains signal integrity while eliminating the need for paired differential traces, thereby reducing PCB area and ball count

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12405629B2High-speed signaling system with ground referenced signaling (GRS) over substrate

Publication Date: 2025.09.02 NVIDIA CORP

AI summary

A system includes a first coupled to a printed circuit board (PCB) and a second device coupled to the PCB. The system further includes a link coupled with the first device, the second device, and the PCB. The link includes a clock lane associated with associated with transmitting a clock signal and one or more data lanes corresponding to the clock lane, where the link is configured to transmit ground referenced signaling (GRS).