Image Sensor Voltage Provider for SNR and Fill Factor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor process sizes for image sensors decrease below 30 μm, the signal-to-noise ratio (SNR) of image sensors drops while maintaining a high fill factor becomes challenging due to smaller storage capacitors.
Innovation Solution
Incorporating a voltage provider to supply extra voltage to storage capacitors, which is variable based on image brightness, allowing the image sensor to maintain or increase SNR and fill factor by increasing the charging capacity of the capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the semiconductor process size is reduced below 30 μm to decrease the size of the image sensor, then the fill factor increases due to smaller storage capacitors, but the signal-to-noise ratio (SNR) drops
Solution Approach 1:
The patent applies parameter changes by providing an extra voltage (e.g., 3.3V or 5V) to the storage capacitors in addition to the normal operating voltage. This voltage parameter change increases the charging capacity of the capacitors, allowing them to store more signal charge even though their physical size is reduced. The relationship Q=CV shows that increasing voltage V compensates for reduced capacitance C, thereby maintaining SNR while enabling smaller capacitor dimensions for improved fill factor.
2Area of moving object
If the storage capacitor size is reduced to increase the fill factor, then more area is available for light sensing, but the charging capacity of the capacitor decreases leading to lower SNR
Solution Approach 1:
The patent changes the voltage parameter supplied to the storage capacitors by introducing an extra voltage source. This allows the capacitors to achieve higher charging capacity (Q=CV) despite their reduced physical size, thereby resolving the contradiction between maximizing light sensing area and maintaining sufficient charging capacity for high SNR performance.
Solution Approach 2:
The patent addresses the capacity limitation by adding a voltage dimension to the charging equation. Instead of solely relying on increasing capacitance (area-based approach), the solution introduces a voltage boost mechanism that operates in a different parameter space, enabling small capacitors to achieve high charging capacity through elevated voltage operation.
Data Source
AI summary
An image sensor includes a transistor, at least one storage capacitor and a voltage provider. The at least one storage capacitor is connected to the transistor. The voltage provider is electrically connected to the transistor and configured to provide an extra voltage for the at least one storage capacitor. The extra voltage is variable in response to images with different brightness. The image sensor includes the voltage provider to provide extra voltage to increase the charging capacity of the storage capacitor. The Signal-Noise-Ratio of the image sensor won't be affected and the fill factor is able to be maintained at a certain level.