Pulsed Time-of-Flight Sensor Pixel Array Segmentation
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Solution Overview
Problem
Current pulsed Time-of-Flight (pToF) sensor technologies face challenges in scaling up due to issues such as large pixel size, reduced fill-factor, high power consumption, and difficulties in distributing high-speed clock signals, which hinder the development of large-scale arrays for applications like autonomous driving under strong sunlight conditions.
Innovation Solution
A pToF sensor and pixel array design that includes a photo-sensitive unit, a time-to-analog conversion unit within each pixel, and an analog-to-digital conversion circuit outside the pixels, allowing for a shared conversion circuit setup that reduces the need for high-speed clock signal distribution and parasitic RC components, enabling smaller layout area and lower power consumption while maintaining high fill-factor and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If pToF sensors are scaled up to large arrays, then coverage area and detection capability are improved, but pixel size increases and fill-factor decreases
Solution Approach 1:
The patent divides the conversion function into two segments: time-to-analog conversion is performed within each pixel, while analog-to-digital conversion is performed externally by shared circuits. This segmentation allows pixels to be smaller with larger photo-sensitive areas, while still achieving the required conversion capabilities for large-scale arrays.
Solution Approach 2:
The patent implements shared analog-to-digital conversion circuits that serve multiple pixels simultaneously. These external conversion circuits provide universal functionality across the entire pixel array, reducing the need for dedicated high-speed clock distribution to each pixel and improving the fill-factor.
2Measurement precision
If conversion circuits are integrated inside each pixel, then conversion precision is improved, but power consumption and device complexity increase
Solution Approach 1:
The conversion process is segmented into two stages: time-to-analog conversion within each pixel (low power) and analog-to-digital conversion externally (shared across pixels). This segmentation reduces the power burden on individual pixels while maintaining conversion precision through the external shared circuits.
Solution Approach 2:
Multiple pixels share common analog-to-digital conversion circuits, merging the conversion function across the array. This sharing approach reduces total power consumption and device complexity while maintaining the precision required for accurate time-of-flight measurements.
3Measurement precision
If high-speed clock signals are distributed to each pixel, then timing precision is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent extracts the complex analog-to-digital conversion function from individual pixels and places it in external shared circuits. This extraction eliminates the need for complex high-speed clock signal distribution to each pixel, simplifying manufacturing while maintaining timing precision through the external conversion architecture.
4Quantity of substance
If pixel size is reduced for high-resolution arrays, then array density is improved, but fill-factor and signal detection capability deteriorate
Solution Approach 1:
The conversion function is segmented between intra-pixel time-to-analog conversion and external analog-to-digital conversion. This allows pixels to be minimized in size for high-density arrays while the external conversion circuits compensate for the reduced photo-sensitive area, maintaining detection capability.
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 design enables the implementation of large-scale pToF pixel arrays with improved fill-factor, reduced power consumption, and enhanced performance, suitable for applications like autonomous driving, by decoupling photon capture and readout timing and supporting flexible operation modes.
Implementation Method 1
a photo sensitive unit configured to detect a return signal of a light pulse signal
Data Source
AI summary
A pToF sensor, a pToF pixel array and an operation method therefor are provided. The pToF pixel array includes a plurality of pToF pixels distributed in an array, a control circuit, and a conversion circuit. Each of the pToF pixels includes a photo sensitive unit configured to detect a return signal of a light pulse signal, and a first conversion unit configured to convert a time signal corresponding to each of the pToF pixels to an analog signal. The control circuit is connected to each of the pToF pixels, and configured to control an operation mode of each of the pToF pixels. The conversion circuit is connected to each of the pToF pixels, and configured to calculate a time-of-fight corresponding to each of the pToF pixels according to the analog signal corresponding to each of the pToF pixels.