Picosecond Sensor Network Synchronization via Active Feedback
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Solution Overview
Problem
Current sensor systems face challenges in achieving picosecond time measurement accuracy due to manufacturing variations, temperature, and power supply voltage mismatches, which affect clock synchronization, and existing protocols like PTP and White Rabbit do not provide sufficient precision for applications like PET, LiDAR, and FLIM.
Innovation Solution
A sensor network with a sensor controller and daisy-chained sensor modules using custom integrated circuits and a physical layer protocol for picosecond time synchronization, employing a Phase-Locked Loop (PLL) for accurate delay measurements and a master-slave algorithm to synchronize chips, allowing for precise time digitization and correction for variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive synchronization approach is used with matched trace lengths and transmission lines, then device complexity is reduced, but measurement precision deteriorates due to manufacturing variations and temperature/voltage mismatches causing time skew
Solution Approach 1:
The patent implements an active feedback-based synchronization system where a master sensor module measures round-trip time delays to slave modules and sends correction signals. Each slave module adjusts its local clock based on feedback from the master, continuously compensating for trace mismatches, temperature variations, and voltage fluctuations. This feedback mechanism transforms the static passive approach into a dynamic system that actively corrects timing errors, resolving the contradiction between simplicity and precision.
Solution Approach 2:
The patent introduces a master sensor module as an intermediary that coordinates synchronization across the network. The master module acts as a central reference, measuring time delays to each slave module and distributing correction signals. This intermediary approach allows individual modules to be synchronized to the master without requiring complex peer-to-peer coordination, achieving high precision while maintaining relatively simple individual module designs.
2Productivity
If sensor chips are added to improve system sensitivity and measurement throughput, then productivity increases, but device complexity increases due to difficulty in adding chips and maintaining synchronization
Solution Approach 1:
The patent designs sensor modules with universal functionality where each module (master or slave) contains identical core components including photodetectors, TDCs, and PLLs. The daisy-chain architecture allows any module to potentially become a master, and all modules can function as slaves. This universality means that adding new sensor chips does not require redesigning existing modules - they can be simply inserted into the daisy chain and automatically integrated into the synchronization network, enabling scalability without proportionally increasing complexity.
Solution Approach 2:
The patent divides the sensor system into independent, modular sensor modules that can be individually added or removed. Each module is a self-contained unit with its own synchronization capabilities. The daisy-chain architecture segments the network into discrete units connected through standardized interfaces, allowing the system to scale from a few modules to many modules without requiring complete system redesign. This segmentation enables high productivity through parallel measurement capabilities while managing complexity through modular design.
3Measurement precision
If picosecond time measurement accuracy is achieved through active synchronization, then measurement precision improves, but device complexity increases due to PLL circuits and calibration requirements
Solution Approach 1:
The patent combines multiple functions into integrated circuits within each sensor module. The PLL (Phase-Locked Loop) is integrated with the TDC (Time-to-Digital Converter) and other timing components on the same chip or module. This merging of functions reduces the number of discrete components and interconnections required, lowering overall device complexity while maintaining picosecond precision. The integrated design allows the complex synchronization logic to be implemented in a compact, manageable form factor.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables reliable picosecond accuracy in time synchronization across sensor modules, improving system sensitivity and accuracy, and allowing for precise localization and detection in applications like PET, LiDAR, and FLIM, while being adaptable to temperature and voltage changes.
Implementation Method 1
employing a Phase-Locked Loop (PLL) for accurate delay measurements
Implementation Method 2
precise measurement of photon time-of-flight (ToF) allows precise quantification of the spatial location of an event
Implementation Method 3
the event of interest is the generation of fluorescence photons by a laser pulse
Data Source
AI summary
A sensor network, which includes a sensor controller serially coupled to a plurality of sensor modules, is configured to program the sensor modules so as to transfer measurement data to the sensor controller and to synchronize the sensor modules to picosecond accuracy via on-chip or on-module custom circuits and a physical layer protocol. The sensor network has applications for use in PET, LiDAR, FLIM and flow cytometry applications. Synchronization, within picosecond accuracy, is achieved through use of a picosecond time digitization circuit. The picosecond time digitization circuit is used to measure on-chip delays with high accuracy and precision. The delay measurements are directly comparable between separate chips even with voltage and temperature variations between chips.