Multi-Lane Optical Transceiver Lane Drop Detection and Master Switching

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Solution Overview

Problem

Multi-lane optical transceivers face challenges in maintaining high data rates and power efficiency due to the use of per lane phase interpolators and phase-locked loops, which consume significant area and power, and require seamless lane switching without affecting active channels.

Innovation Solution

Implement a fast digital lane drop detection system that uses a single PLL/PPM master architecture and a 'difference-of-the-difference' technique to monitor lane validity and dynamically switch the master lane, reducing the number of phase interpolators and allowing seamless lane-switching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If per lane phase interpolators and phase-locked loops are used for each transmitter and receiver block, then frequency information transfer is achieved, but power consumption and area increase significantly

Engineering Contradiction:
Improvefrequency information transferVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent merges multiple per-lane phase-locked loops into a single shared phase-locked loop for the entire multi-lane transceiver. This consolidation maintains frequency information transfer reliability while dramatically reducing power consumption and chip area by eliminating redundant circuitry across all lanes.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single phase-locked loop is designed to serve multiple lanes universally, dynamically switching between them to provide frequency information transfer. This multi-functional approach allows one circuit to perform the work of many, reducing overall power consumption while maintaining the required reliability for each lane.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If per lane phase interpolators and phase-locked loops are used for each transmitter and receiver block, then frequency information transfer is achieved, but device area increases significantly

Engineering Contradiction:
Improvefrequency information transferVSAvoidchip area
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges multiple per-lane phase-locked loops into a single shared phase-locked loop for the entire multi-lane transceiver. This consolidation maintains frequency information transfer reliability while dramatically reducing chip area by eliminating redundant circuitry across all lanes.

Inventive Principle:
Principle #5Merging (Combining)

3Adaptability or versatility

If dynamic lane switching is implemented, then adaptability is improved, but lane drop detection complexity increases

Engineering Contradiction:
Improvelane switching capabilityVSAvoiddetection system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where the receiver continuously monitors lane quality metrics and provides feedback to the transmitter. This feedback loop enables automatic lane drop detection and dynamic lane switching without requiring complex detection systems, as the feedback carries the necessary quality information for decision-making.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system uses self-service by having the receiver automatically detect lane drops and trigger reconfiguration without external intervention. The embedded lane quality monitoring and automatic lane selection enable the system to self-manage adaptability while keeping detection complexity manageable through integrated rather than separate detection circuits.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4622136A1Fast digital lane drop detection system for multi-lane direct detect transceivers
Publication Date: 2025.09.24 CISCO TECHNOLOGY INC
  • EP4622136A1 patent drawingFigure 1A
  • EP4622136A1 patent drawingFigure 1B
  • EP4622136A1 patent drawingFigure 2

AI summary

Lane drop detection techniques for multi-lane optical transceivers are provided. In one aspect, a method includes capturing a phase interpolator (PI) control word for each lane of an optical transceiver; determining a lane difference between a master lane and each non-master lane; calculating a difference associated with each non-master lane, wherein the difference associated with a given non-master lane is calculated as a difference between the lane difference associated with the given non-master lane and a reference lane difference associated with the given non-master lane; upon determining that at least one of the differences has reached a drift threshold, determining that the master lane or one or more of the non-master lanes is invalid based on which of the differences have reached the drift threshold; and performing a control action when the master lane or one or more of the non-master lanes is invalid.