Reducing TOF Pixel Area via Shared Readout Circuitry
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Solution Overview
Problem
Modern time-of-flight (TOF) systems have large pixel sizes due to the inclusion of complex analog and digital circuitry, which increases the area required for each pixel and limits the number of pixels that can be accommodated on an IC chip, affecting resolution and cost-effectiveness.
Innovation Solution
The solution involves off-loading certain components and functionality from within the pixel to reduce the area required for dedicated electronics, allowing for smaller pixel sizes while maintaining high performance features like dealiasing and dynamic range, by digitizing analog output signals and processing them outside the pixel array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex analog and digital circuitry is included within each pixel, then high performance features (dealiasing, dynamic range) are maintained, but pixel size increases and chip area expands
Solution Approach 1:
The patent extracts complex analog circuitry (integrators, sample-and-hold circuits, differential amplifiers) from the pixel array and implements them as shared resources in a separate readout circuitry block. This allows each pixel to be reduced to essential components (photodetector, transfer gate, reset gate) while maintaining full functionality through the shared external circuitry.
Solution Approach 2:
The patent implements shared readout circuitry that serves multiple pixels simultaneously. The integrators, sample-and-hold circuits, and differential amplifiers are universal resources that can process signals from any pixel in the array, eliminating the need for dedicated circuitry in each pixel and enabling multi-functionality across the system.
2Extent of automation
If dedicated electronics are included in each pixel, then processing capability is enhanced, but the number of pixels that can be accommodated on the IC chip decreases
Solution Approach 1:
The patent merges the processing functions that were previously distributed across individual pixels into a centralized shared readout circuitry block. By combining integrators, sample-and-hold circuits, and differential amplifiers into shared resources, the system maintains full processing capability while accommodating a significantly larger number of pixels on the chip.
3Area of stationary object
If pixel size is reduced, then chip area and cost are reduced, but the complexity of achieving high performance features increases
Solution Approach 1:
The patent moves the complex circuitry from the two-dimensional pixel plane to a separate third dimension (external readout circuitry block). This spatial reorganization allows small pixels to maintain simplicity while the system achieves high performance through the shared circuitry in a different architectural dimension, effectively decoupling pixel size from system complexity.
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 enables the implementation of a feature-rich TOF system with smaller pixel sizes, reducing the overall chip area and enabling higher resolution arrays, while maintaining enhanced functionality such as ambient resilience and dynamic range.
Implementation Method 1
a pixel detector PD and associated circuitry
Data Source
AI summary
Embodiments of the present invention provide methods to produce a high performance, feature rich TOF system, phase-based or otherwise using small TOF pixels, single-ended or preferably differential, as well as TOF systems so designed. IC chip area required for pixels is reduced by intelligently off-loading or removing from within the pixel certain components and/or functionality. In some embodiments during a single TOF system capture period, analog values from each pixel are repeatedly sampled and converted to digital values, which are combined and manipulated on the sensor chip. Combining this plurality of values enables appropriately compact data from the sensor chip. Embodiments of the present invention implement a TOF system with high ambient light resilience, high dynamic range, low motion blur and dealiasing support, while advantageously reducing pixel area size relative to prior art TOF pixels.