Photosensor Segmentation for Signal-to-Noise Ratio
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Solution Overview
Problem
Existing photosensors face challenges in varying their response effectively across different lighting conditions, as they either suffer from high photon shot noise at high light levels or increased read noise at low light levels, due to limitations in capacitance and full well capacity.
Innovation Solution
A photosensor design that splits the photosensing area into multiple smaller photosensitive regions, allowing all regions to collect charge at high light levels and only some at low light levels, with unused regions connected to a lower potential to maintain capacitance and increase signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the photosensor uses a large full well capacity to reduce photon shot noise at high light levels, then the signal-to-noise ratio improves, but the output voltage swing decreases due to increased capacitance
Solution Approach 1:
The photosensor is divided into multiple photosensitive regions (first photosensitive region, second photosensitive region, third photosensitive region) that can be independently connected or disconnected from the signal collection means. This segmentation allows selective activation of regions based on lighting conditions, enabling the system to optimize between signal-to-noise ratio and output voltage swing by using only the necessary number of regions for the current light level.
2Strength
If the photosensor reduces full well capacity to increase output voltage swing, then the capacitance decreases and voltage swing increases, but the signal-to-noise ratio deteriorates due to increased photon shot noise
Solution Approach 1:
The photosensor implements dynamic switching between different numbers of photosensitive regions based on lighting conditions. The switching means selectively connects or disconnects photosensitive regions from the signal collection means, allowing the system to adapt its capacitance and full well capacity in real-time. This dynamic adjustment enables optimization of both output voltage swing and signal-to-noise ratio across varying light levels.
3Strength
If the photosensor uses a small number of photosensitive regions to maintain high output voltage swing, then the capacitance remains low and voltage swing is maximized, but the full well capacity decreases increasing photon shot noise
Solution Approach 1:
The photosensor is divided into multiple photosensitive regions (first photosensitive region, second photosensitive region, third photosensitive region) that can be independently connected or disconnected from the signal collection means. This segmentation allows selective activation of regions based on lighting conditions, enabling the system to optimize between signal-to-noise ratio and output voltage swing by using only the necessary number of regions for the current light level.
4Quantity of substance
If the photosensor increases the number of photosensitive regions to increase full well capacity, then the full well capacity increases reducing photon shot noise, but the device complexity increases
Solution Approach 1:
The photosensor is divided into multiple photosensitive regions (first photosensitive region, second photosensitive region, third photosensitive region) that can be independently connected or disconnected from the signal collection means. This segmentation allows selective activation of regions based on lighting conditions, enabling the system to optimize between signal-to-noise ratio and output voltage swing by using only the necessary number of regions for the current light level.
Solution Approach 2:
The switching means serves multiple functions: it selectively connects or disconnects photosensitive regions, it controls the capacitance of the photosensor, and it optimizes the signal-to-noise ratio. This multi-functionality reduces the need for separate circuits for each function, thereby managing device complexity while achieving multiple optimization goals.
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 design enhances the signal generated by a factor of M, improving the signal-to-noise ratio and enabling the photosensor to operate effectively under both high and low light conditions by managing capacitance and noise levels.
Implementation Method 1
Responsivity is a measure of the effectiveness of a photosensor in converting incident electromagnetic radiation into electrical current or voltage
Data Source
AI summary
A photosensor includes a plurality of photosensitive regions including a first photosensitive region connected to a first voltage reference, and at least one additional photosensitive region. A signal collector is connected to the first photosensitive region. At least one switching device is for switching the at least one additional photosensitive region between the first voltage reference and a second voltage reference that is less than the first voltage reference, and for reversibly connecting the at least one additional photosensitive region to the signal collector so that the photosensor is variably responsive to different light levels.