Light-Receiving Device Dual Capacitor Charge Transfer
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Solution Overview
Problem
Light-receiving sensors face a trade-off between saturation charge amount and conversion gain, limiting their ability to accurately measure small light quantity changes with high sensitivity and speed, particularly in absorption analysis applications.
Innovation Solution
A light-receiving device with a pixel circuit configuration that includes two capacitive elements and switch means, allowing for effective saturation capacity of the first capacitive element to be 10 to 5,000 times that of the second, enabling efficient photoelectric charge transfer and voltage conversion, thereby enhancing sensitivity and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the saturation charge amount is increased by increasing the capacity of floating diffusion, then the saturation performance is improved, but the conversion gain is reduced
Solution Approach 1:
The patent divides the capacitive element into two separate capacitive elements (first capacitive element and second capacitive element) with different capacities. The first capacitive element has a large capacity for accumulating saturation charge, while the second capacitive element has a small capacity for maintaining high conversion gain. This segmentation resolves the trade-off by allowing each element to fulfill its specific function independently.
Solution Approach 2:
The patent assigns different functional characteristics to different parts of the charge accumulation system. The first capacitive element is designed with large capacity for saturation performance, while the second capacitive element is designed with small capacity for high conversion gain. This local differentiation allows the system to simultaneously achieve both saturation performance and conversion gain without compromise.
2Measurement precision
If the conversion gain is increased by decreasing the capacity of floating diffusion, then the sensitivity is improved, but the saturation charge amount is reduced
Solution Approach 1:
The patent separates the charge accumulation function into two capacitive elements with different capacity characteristics. The first capacitive element handles saturation charge accumulation with large capacity, while the second capacitive element handles conversion gain with small capacity. This segmentation eliminates the need to choose between the two conflicting requirements.
Solution Approach 2:
The patent implements different capacity characteristics in different locations of the charge handling path. The first capacitive element near the light-receiving element has large capacity for saturation, while the second capacitive element in the signal path has small capacity for high conversion gain. This local quality differentiation allows simultaneous optimization of both parameters.
3Measurement precision
If the light quantity irradiated onto the specimen is increased to detect extremely small amounts of substance, then the detection capability is improved, but the saturation charge amount requirement increases
Solution Approach 1:
The patent divides the charge handling path into two stages with different capacitive elements. The first capacitive element can accommodate large charge amounts from high light irradiation, while the second capacitive element provides high conversion gain for detecting small changes. This segmentation enables the system to handle both high light quantities and small detection requirements simultaneously.
Solution Approach 2:
The patent changes the capacity parameter of the capacitive elements to match different operational requirements. The first capacitive element has large capacity parameter for handling saturation charge from high light irradiation, while the second capacitive element has small capacity parameter for maintaining high conversion gain. This parameter differentiation resolves the contradiction between detection capability and saturation charge amount.
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
The solution enables high saturation performance and high sensitivity analysis while maintaining high-speed processing and wide optical wavelength compatibility, effectively addressing the limitations of existing sensors in absorption analysis and other applications.
Implementation Method 1
a light-receiving element, a first capacitive element (1) that accumulates a photoelectric charge produced by light received by the light-receiving element
Data Source
AI summary
A light-receiving device that achieves both high saturation performance and high sensitivity performance includes a light-receiving pixel including a light-receiving element, a first capacitive element that accumulates a photoelectric charge produced by light received by the light-receiving element, a second capacitive element that accumulates a transferred portion of an amount of the photoelectric charge accumulated in the capacitive element, a switch means for turning on and off a photoelectric charge transfer operation from the capacitive element to the capacitive element, a resetting switch means for resetting the capacitive element and the capacitive element, a pixel selecting switch means, and a source follower switch means. An effective saturation capacity of the capacitive element is 10 to 5,000 times an effective saturation capacity of the capacitive element.