Multi-Lane Optical Transceiver Clocking for Seamless Lane Switching
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Solution Overview
Problem
Existing multi-lane optical transceivers face challenges in efficiently tracking frequency errors and lane status changes without causing bit errors, leading to increased silicon area and power consumption due to multiple phase interpolators or phase locked loops.
Innovation Solution
Implement a firmware-based feedback loop in multi-lane optical transceivers to dynamically track frequency errors and monitor lane status, using a tunable oscillator and fractional phase-locked loops to minimize chip area and power, enabling seamless lane-switching with minimal errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple independent phase interpolators or phase locked loops are used per lane for PPM tracking, then lane-switching capability is improved, but silicon area and power consumption increase
Solution Approach 1:
The patent merges the PPM tracking function across multiple lanes by using a single shared phase interpolator and phase locked loop instead of having independent units per lane. The system captures PPM values from multiple lanes and uses firmware to select and transfer the appropriate PPM information, eliminating the need for redundant hardware on each lane while maintaining seamless lane-switching capability.
Solution Approach 2:
The shared phase interpolator and phase locked loop are designed to serve multiple lanes universally. The firmware-based PPM tracking system can dynamically adapt to track frequency errors on any active lane, making the single hardware unit multi-functional across all lanes rather than dedicated to one lane per unit.
2Adaptability or versatility
If multiple independent phase interpolators or phase locked loops are used per lane for PPM tracking, then lane-switching capability is improved, but power consumption increases
Solution Approach 1:
The patent merges the PPM tracking function across multiple lanes by using a single shared phase interpolator and phase locked loop instead of having independent units per lane. The system captures PPM values from multiple lanes and uses firmware to select and transfer the appropriate PPM information, eliminating the need for redundant hardware on each lane while maintaining seamless lane-switching capability.
Solution Approach 2:
The shared phase interpolator and phase locked loop are designed to serve multiple lanes universally. The firmware-based PPM tracking system can dynamically adapt to track frequency errors on any active lane, making the single hardware unit multi-functional across all lanes rather than dedicated to one lane per unit.
3Area of stationary object
If firmware-based feedback loop with shared phase interpolator is used, then silicon area and power consumption are reduced, but frequency error tracking precision may worsen
Solution Approach 1:
The patent implements a firmware-based feedback loop that continuously captures PPM values from multiple lanes, monitors frequency errors, and dynamically transfers the most accurate PPM information to the output. This feedback mechanism ensures that even with a shared phase interpolator, the system maintains high frequency error tracking precision by adaptively selecting the best available data from any active lane.
Solution Approach 2:
The system performs preliminary capture of PPM values from all lanes before lane switching occurs. By pre-capturing and storing PPM information from multiple lanes, the firmware is prepared to immediately transfer the correct PPM data when a lane switch happens, maintaining precision without requiring additional hardware.
4Use of energy by stationary object
If firmware-based feedback loop with shared phase interpolator is used, then power consumption is reduced, but frequency error tracking precision may worsen
Solution Approach 1:
The patent implements a firmware-based feedback loop that continuously captures PPM values from multiple lanes, monitors frequency errors, and dynamically transfers the most accurate PPM information to the output. This feedback mechanism ensures that even with a shared phase interpolator, the system maintains high frequency error tracking precision by adaptively selecting the best available data from any active lane.
Solution Approach 2:
The system performs preliminary capture of PPM values from all lanes before lane switching occurs. By pre-capturing and storing PPM information from multiple lanes, the firmware is prepared to immediately transfer the correct PPM data when a lane switch happens, maintaining precision without requiring additional hardware.
Data Source
AI summary
Frequency error tracking and lane monitoring techniques for multi-lane optical transceivers are provided. In one aspect, a method includes capturing phase and frequency information recovered by clock-and-data recovery circuits from data traveling along a plurality of lanes of an optical transceiver, with one of the lanes being a master lane; determining a frequency error based on the phase and frequency information of the master lane; outputting, by a tunable oscillator, a reference clock based on the frequency error; and controlling the optical transceiver based on i) a transmitter clock signal generated by a transmitter phase-locked loop (PLL) using the reference clock signal, and ii) a receiver clock signal generated by a receiver PLL using the reference clock signal.