Photoelectric Conversion Input Node Capacitance Switching for Dynamic Range
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Solution Overview
Problem
The existing photoelectric conversion apparatuses face challenges in resetting the input node to a predetermined potential due to increased resistance from multiple gates, which can lead to lowered reset performance and reduced dynamic range.
Innovation Solution
The apparatus includes a photoelectric conversion portion, an amplification transistor, a first transfer transistor, a second transfer transistor, and a reset transistor, where the second transfer transistor controls the capacity value of the input node by being turned on or off, allowing for increased dynamic range and sensitivity by adjusting the capacity of the floating diffusion portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple gates are arranged between the reset transistor and input node to control capacity, then the dynamic range can be expanded, but the gate length increases causing higher resistance and lowered reset performance
Solution Approach 1:
The patent divides the capacity control function into two separate transistors: a first transfer transistor for transferring electric charges and a second transfer transistor for controlling the capacity value of the input node. This segmentation allows each transistor to have a shorter gate length, reducing resistance while maintaining the ability to expand dynamic range through capacity control.
Solution Approach 2:
The patent introduces a second transfer transistor as an intermediary element between the reset transistor and the input node. This intermediary controls the capacity value of the input node without requiring a long gate length, thus preventing resistance increase while enabling dynamic range expansion through capacity adjustment.
2Adaptability or versatility
If a transistor for increasing capacity is connected between the input node and reset transistor, then the dynamic range is expanded, but the gate length becomes longer increasing resistance and lowering reset performance
Solution Approach 1:
The patent segments the capacity control function from the charge transfer function by using separate first and second transfer transistors. This allows the second transfer transistor to control capacity with a shorter gate length, reducing resistance while maintaining dynamic range expansion capability.
Solution Approach 2:
The patent makes the capacity value of the input node dynamically controllable by using the second transfer transistor to switch between different capacity states (when on or off). This dynamic control achieves dynamic range expansion without requiring a fixed long gate length structure.
3Adaptability or versatility
If multiple gates are arranged to control input node capacity, then the dynamic range increases, but the resistance increases preventing proper resetting of the input node
Solution Approach 1:
The patent separates capacity control from charge transfer by using distinct first and second transfer transistors. This segmentation enables independent optimization where the second transfer transistor can control capacity with minimal resistance impact, ensuring proper reset operation while maintaining dynamic range expansion.
Solution Approach 2:
The second transfer transistor acts as an intermediary that controls the capacity value of the input node without creating significant resistance. This intermediary enables easy reset operation by the reset transistor while still providing dynamic range expansion through capacity control.
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 configuration enhances the reset performance and expands the dynamic range of the photoelectric conversion apparatus by controlling the capacity of the floating diffusion portion, preventing the lowering of reset performance and improving sensitivity.
Implementation Method 1
a photoelectric conversion portion 201, an amplification transistor 206
Data Source
AI summary
A photoelectric conversion apparatus includes a photoelectric conversion portion, an amplification transistor having an input node, a first transfer transistor, a second transfer transistor arranged between the first transfer transistor and the input node, and a reset transistor connected to the input node. When electric charges are transferred from the photoelectric conversion portion to the input node, the photoelectric conversion apparatus switches a capacity value of the input node by controlling the second transfer transistor to be on or off.