One-Transistor Image Sensor Pixel Layout for Dynamic Range
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Solution Overview
Problem
As pixel sizes in image sensors continue to decrease, there is a predicted scenario where only one pixel transistor other than a transfer transistor can be accommodated within a pixel, necessitating a more efficient pixel arrangement to maintain high resolution and dynamic range.
Innovation Solution
A solid-state imaging device with a pixel array unit where each pixel includes a photoelectric conversion element, a floating diffusion region, a transfer transistor, and one pixel transistor, which can be either a reset transistor, a switching transistor, an amplification transistor, or a selection transistor, arranged in a two-dimensional matrix shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is reduced to increase resolution, then the number of pixels increases, but the number of transistors that can be accommodated in each pixel decreases
Solution Approach 1:
The pixel is divided into functional groups where the photoelectric conversion element and transistors are segmented into specific spatial arrangements. The pixel transistor is positioned in a dedicated region separate from the photoelectric conversion element, allowing independent optimization of each component's size and function within the constrained pixel area.
Solution Approach 2:
The patent utilizes vertical stacking and three-dimensional spatial arrangement to accommodate necessary transistor functions. By arranging components in multiple layers and utilizing vertical space, the design compensates for the reduced horizontal area available in miniaturized pixels, maintaining functional complexity despite size reduction.
2Device complexity
If only one pixel transistor is available per pixel, then device complexity is reduced, but signal processing capability and dynamic range are limited
Solution Approach 1:
The single pixel transistor is designed to perform multiple functions including signal amplification, reset operations, and selection for readout. By making this single transistor multi-functional, the patent maintains signal processing capability and dynamic range without requiring additional transistors that would increase device complexity.
Solution Approach 2:
Multiple transistor functions are merged into a single pixel transistor structure. The patent combines amplification, reset, and selection capabilities into one transistor, eliminating the need for separate transistors for each function and thereby reducing device complexity while preserving signal processing performance.
3Measurement precision
If pixel area is reduced, then more pixels can be packed for higher resolution, but available space for photoelectric conversion and transistor operation decreases
Solution Approach 1:
Different regions within the pixel are assigned different functional qualities optimized for their specific purposes. The photoelectric conversion element occupies one region with characteristics optimized for light detection, while the pixel transistor occupies another region with characteristics optimized for signal processing, allowing each component to maintain adequate size and performance despite overall pixel reduction.
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 enables high resolution and dynamic range even when only one pixel transistor is available per pixel, by effectively utilizing the available transistor space and optimizing signal processing within the pixel unit.
Implementation Method 1
pixels each having a photoelectric conversion element
Data Source
AI summary
The present disclosure relates to a solid-state imaging device and an electronic apparatus capable of achieving a high resolution and a high dynamic range by arranging a large-sized pixel transistor in a case where only one pixel transistor other than a transfer transistor is arrangeable within one pixel. The solid-state imaging device includes a pixel array unit that includes pixels each having a photoelectric conversion element, a floating diffusion region, a transfer transistor, and one pixel transistor other than a transfer transistor, the pixels being two-dimensionally arranged in a matrix shape. The one pixel transistor is any one of a reset transistor, a switching transistor, an amplification transistor, or a selection transistor. The present disclosure is applicable to a solid-state imaging device having small-sized pixels, for example.