Time-Synchronized LiDAR Sensor Network for Picosecond Clock Alignment
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Solution Overview
Problem
Current sensor systems for applications like PET, LiDAR, and FLIM face challenges in achieving picosecond-level time synchronization accuracy due to manufacturing variations, temperature, and power supply mismatches, which are not adequately addressed by existing passive synchronization methods.
Innovation Solution
A sensor network architecture using custom integrated circuits and a physical layer protocol for picosecond time digitization, incorporating a Phase-Locked Loop (PLL) and Time Digitization Units (TDUs) to synchronize sensor modules with sub-100 ps accuracy, and a master-slave algorithm for fine time control across daisy-chained network elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive synchronization approach is used with matched trace lengths and clock buffers, then device complexity is reduced, but measurement precision deteriorates due to manufacturing variations and temperature mismatches
Solution Approach 1:
The patent implements an active feedback-based synchronization system where each sensor chip measures its own time skew relative to a reference and communicates this measurement back to a central controller. The controller then calculates compensation values and sends correction signals to each chip's clock buffer, continuously adjusting for drift caused by temperature and voltage variations. This closed-loop feedback mechanism maintains picosecond-level synchronization accuracy without requiring complex manual matching of all trace lengths.
Solution Approach 2:
The patent replaces the passive mechanical/electrical matching approach (manually matching trace lengths and buffer characteristics) with an active electronic measurement and correction system. Instead of relying on physical symmetry to achieve synchronization, the system electronically measures actual time skews and applies digital compensation, substituting physical precision requirements with electronic correction capabilities.
2Productivity
If sensor chips are added to the system to improve sensitivity and accuracy, then productivity increases, but device complexity worsens due to redesign requirements for clock distribution
Solution Approach 1:
The patent segments the synchronization system into independent, modular sensor chips, each with its own integrated clock buffer and time skew measurement circuitry. Instead of a monolithic clock distribution network requiring global redesign, each chip operates as an autonomous unit that measures and reports its own synchronization status. This modular segmentation allows new chips to be added to the network without redesigning the entire clock distribution architecture.
Solution Approach 2:
The patent creates a universal synchronization protocol and interface that works across all sensor chips regardless of their position in the network or specific manufacturing variations. Each chip implements the same standardized measurement and communication functions, allowing them to be freely added, removed, or replaced without requiring system-wide redesign. The centralized controller universally manages all chips through a common protocol.
3Ease of manufacture
If trace lengths and clock buffers are assumed identical to minimize time skew, then ease of manufacture improves, but reliability deteriorates due to voltage and temperature variations causing desynchronization
Solution Approach 1:
The patent enables each sensor chip to self-measure its own time skew relative to the reference clock and self-report this measurement to the central controller. Each chip autonomously determines its synchronization status without requiring external calibration or manual adjustment. The chip's own measurement circuitry and communication interfaces allow it to service its own synchronization needs, eliminating the need for precise manual matching during assembly.
Solution Approach 2:
The patent dynamically adjusts the effective clock phase parameters for each chip based on measured time skews caused by voltage and temperature variations. Instead of relying on fixed physical matching that becomes unreliable under varying conditions, the system electronically modifies clock timing parameters in real-time to compensate for environmental changes, maintaining synchronization reliability across different operating conditions.
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 or FLIM applications. Synchronization, within picosecond accuracy, is achieved through use of a picosecond time digitization circuit. Specifically, 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.