Dispersed Bit Counters for SPAD Sensor Wiring Area Reduction
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Solution Overview
Problem
Current single photon avalanche diode (SPAD) sensors in LIDAR systems face challenges in efficiently counting high-bit signals due to wiring constraints and signal delay, which affects the accuracy of distance measurement and signal-to-noise ratio.
Innovation Solution
The implementation of a light receiver with dispersed bit counters across multiple photoelectric conversion portions, utilizing a 24-bit counter circuit to collectively count pulse signals from SPAD sensors, and a control circuit that calculates time-of-flight based on phase differences between lower-bit and higher-bit counter outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If bit counters are centralized in a single location for SPAD sensors, then signal counting can be performed, but wiring area increases and aperture ratio decreases
Solution Approach 1:
The patent divides the bit counters into multiple segments and disperses them across different photoelectric conversion portions rather than centralizing them in one location. Each photoelectric conversion portion has its own dispersed bit counters, which reduces the wiring area required to connect all counters to a central location while maintaining the ability to perform accurate signal counting locally at each pixel.
2Speed
If more wiring is provided for signal transmission, then signal delay can be reduced, but aperture ratio of each pixel decreases
Solution Approach 1:
The patent transitions from a centralized two-dimensional wiring layout to a distributed three-dimensional architecture where bit counters are placed at multiple locations across the sensor array. This dimensional redistribution allows signal transmission paths to be shortened locally at each pixel while maintaining overall system functionality, thereby reducing signal delay without requiring increased wiring area that would reduce aperture ratio.
3Area of moving object
If bit counters are dispersed across photoelectric conversion portions, then aperture ratio increases and wiring area reduces, but device complexity increases
Solution Approach 1:
The patent implements a universal bit counter design that can function effectively whether centralized or dispersed. The same bit counter circuitry is replicated across multiple photoelectric conversion portions, allowing each pixel to perform independent signal counting without requiring complex custom wiring or control logic. This universality simplifies the overall device architecture despite the distributed arrangement, as the same standardized components are used throughout the system.
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 configuration enhances the aperture ratio of each pixel, reduces wiring area, and improves the signal-to-noise ratio, enabling accurate and high-resolution distance measurements in LIDAR systems.
Implementation Method 1
a photoelectric conversion element configured to receive light
Data Source
AI summary
A light receiver includes a plurality of photoelectric conversion portions each of which includes a photoelectric conversion element configured to receive light, and a pulse generator configured to generate a pulse signal corresponding to an amount of light received by the photoelectric conversion element. The light receiver includes a plurality of bit counters each of which is configured to count the pulse signal of the pulse generator, and the plurality of bit counters are dispersed in the plurality photoelectric conversion portions.