TOF Sensor Timing Path Delay Compensation
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Solution Overview
Problem
The variability in response times of reference and return Single-Photon Avalanche Diode (SPAD) arrays in Time-of-Flight (TOF) sensors introduces measurement errors and undermines the accuracy of distance measurements.
Innovation Solution
The integration of a timing reference generator that produces a timing reference signal, which is routed through both arrays via specific paths, including dummy arrangements, to equate the response times across the reference and return arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If separate timing paths are used for reference and return arrays, then device complexity is reduced, but response time variability increases causing measurement errors
Solution Approach 1:
The patent segments the timing reference signal path into multiple equal-length sub-paths, with each SPAD array (reference and return) receiving the signal through dedicated paths of matched length. This segmentation allows independent optimization of each path while ensuring overall timing synchronization, resolving the contradiction between simplified device structure and measurement precision.
Solution Approach 2:
The patent creates equipotential timing conditions by ensuring all timing reference signal paths have equal length and equivalent electrical characteristics. This equalizes the propagation delay across different SPAD arrays, eliminating timing offsets without requiring complex calibration circuits or increasing overall system complexity.
2Measurement precision
If dummy arrangements are added to equalize path lengths, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent introduces dummy circuit elements as intermediary components that act as timing balancers. These dummy arrangements serve as mediators to equalize the electrical path lengths without requiring physical redistribution of active SPAD elements, thus improving measurement precision while maintaining a manageable device structure.
Solution Approach 2:
The patent adjusts the timing characteristics by modifying path length parameters through the addition of dummy arrangements. By changing the electrical length parameter of signal paths to be equal, the system achieves consistent response times across arrays without fundamentally altering the core device architecture or requiring complex reconfiguration.
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
This approach ensures consistent and accurate time-of-flight measurements by eliminating variability in response times, enhancing the reliability of distance calculations and reducing the need for range offset trimming during testing.
Implementation Method 1
A dTOF sensor works by emitting a short pulse of light towards a target and measuring the time it takes for the light to reflect off the target and return to the sensor
Implementation Method 2
Once an incoming photon strikes a SPAD, it triggers the initiation of an avalanche breakdown, the generation of an electrical pulse
Data Source
AI summary
A time-of-flight (TOF) sensor includes a timing generator generating a timing reference, a first array of TOF-related components including rows of TOF-related components, with each row receiving the timing reference, and a dummy row of TOF-related components. The TOF sensor also includes a second array of TOF-related components including rows of TOF-related components, with each row receiving the timing reference, and a dummy row of TOF-related components. A first path delivers the timing reference to the rows of the first array, the first path passing from the timing generator, through the dummy row of TOF-related components in the second array, to the first array of TOF-related components. A second path delivers the timing reference to the rows of the second array, the second path passing from the timing generator, through the dummy row of TOF-related components in the first array, to the second array of TOF-related components.