Pixel Capacitance Element Stabilizes Power Supply Noise in Solid-State Imaging
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Solution Overview
Problem
Existing solid-state imaging apparatuses suffer from image quality degradation due to fluctuations in ground potential and power supply potential caused by the operation of A/D converters, which affect multiple pixels sharing power and ground lines, leading to noise in signal output.
Innovation Solution
Incorporating a capacitance element with one electrode connected to a power supply line and another electrode connected to a ground line in each pixel to stabilize the potential fluctuations, thereby reducing noise and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If A/D converters are included in each pixel to convert analog signals to digital signals, then digital signal output capability is improved, but ground potential and power supply potential fluctuations occur causing noise degradation
Solution Approach 1:
A capacitance element is introduced as an intermediary component between the power supply line and ground line to mediate potential fluctuations. The capacitance element absorbs transient current changes and stabilizes the power supply voltage, preventing potential fluctuations from affecting the pixel circuit and causing noise.
Solution Approach 2:
The capacitance element provides beforehand cushioning by pre-storing electrical energy and preparing to counteract potential fluctuations before they occur. When the A/D converter operates and causes current spikes, the capacitance element immediately compensates by releasing stored energy, cushioning the impact on power supply stability.
2Productivity
If in-pixel readout circuits process large quantities of incident light, then signal processing capability is improved, but potential of column signal lines fluctuates causing ground and power supply potential changes
Solution Approach 1:
The capacitance element serves as an intermediary between the fluctuating readout circuit and the power supply network. It isolates the potential instability caused by high-capacity signal processing from affecting the overall power supply potential, maintaining stability for other pixels sharing the same power and ground lines.
3Device complexity
If multiple pixels share power supply lines and ground lines, then device complexity is reduced, but potential fluctuations in one pixel affect other pixels degrading image quality
Solution Approach 1:
The capacitance element creates an electrical segmentation or isolation zone within each pixel, effectively dividing the shared power supply network into electrically independent zones. This segmentation prevents noise and potential fluctuations from propagating between pixels that share power and ground lines, maintaining image quality consistency while preserving the simplicity of shared power supply architecture.
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 capacitance element effectively suppresses potential fluctuations, enhancing image quality by minimizing noise in the signal output from the pixel circuit and surrounding pixels, thus maintaining image integrity.
Implementation Method 1
at least one of the plurality of pixels includes at least a portion of a capacitance element having a first electrode connected to one of the one or more power supply lines, and a second electrode connected to one of the one or more ground lines
Data Source
AI summary
A solid-state imaging apparatus having a pixel array is provided. The apparatus includes one or more ground lines and one or more power supply lines for supplying power to the pixels. Each of the pixels includes an photoelectric conversion element and an A/D converter for converting an analog signal corresponding to a charge generated by the photoelectric conversion element into a digital signal. At least one of the plurality of pixels includes at least a portion of a capacitance element having a first electrode connected to one of the one or more power supply lines, and a second electrode connected to one of the one or more ground lines.