Pixel Circuit Floating Diffusion Dynamic Range
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Solution Overview
Problem
In photon counting imaging devices, increasing the capacitance of the floating diffusion layer broadens the detectable range of light intensity but decreases the conversion efficiency of light into signal voltage, making it difficult to determine if a single photon is incident, thus limiting the dynamic range.
Innovation Solution
A pixel circuit design with multiple floating diffusion layers of a first conductivity-type between the drain/source and source/drain of a second conductivity-type, where the cathode of a photoelectric converter is electrically connected to the floating diffusion layer, and the anode is of the second conductivity-type, allowing for expanded dynamic range while maintaining conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the capacitance of the floating diffusion layer is increased, then the detectable range of light intensity (dynamic range) is broadened, but the conversion efficiency of light into signal voltage decreases
Solution Approach 1:
The pixel circuit is divided into multiple independent photodiodes, each with its own floating diffusion layer and signal processing path. This segmentation allows each pixel to operate independently with optimized capacitance values, enabling the system to achieve both high conversion efficiency for single-photon detection and expanded dynamic range through the collective capability of multiple pixels with different capacitance characteristics
Solution Approach 2:
The invention changes the capacitance parameter of the floating diffusion layer by reducing it to enable high conversion efficiency for single-photon detection.同时, the patent employs multiple photodiodes with different capacitance values to collectively achieve expanded dynamic range, thus resolving the contradiction between conversion efficiency and dynamic range through parameter optimization and diversification
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 design enables an expanded dynamic range in photon counting imaging devices by reducing capacitance and increasing the number of floating diffusion layers, ensuring the necessary dynamic range is maintained while enhancing conversion efficiency.
Implementation Method 1
the photoelectric converter converts light into an electric charge
Data Source
AI summary
A pixel circuit includes a floating diffusion layer of a first conductivity-type between a drain/source of a second conductivity-type and a source/drain of the second conductivity-type. The source/drain and the drain/source touch the floating diffusion layer. A cathode of a photoelectric converter is electrically connected to the floating diffusion layer. An anode of the photoelectric converter touches the cathode. The cathode is of the first conductivity-type and the anode is of the second conductivity-type.