Photoelectric Conversion Circuit Using Electrostatic Coupling for HDR Pixels
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Solution Overview
Problem
Existing imaging devices face challenges in achieving high dynamic range imaging with small pixel sizes due to increased circuit density and manufacturing costs associated with capacitive coupling wiring, leading to potential yield and cost issues.
Innovation Solution
A photoelectric conversion device with a circuit configuration that utilizes electrostatic coupling between interconnections to control floating diffusion capacitance, eliminating the need for additional circuits to adjust capacitance, thereby reducing complexity and cost while maintaining high dynamic range imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive coupling wiring is added to adjust charge holding capacitance of floating diffusion, then high dynamic range imaging is achieved, but circuit density increases and manufacturing cost increases
Solution Approach 1:
The patent merges the capacitance adjustment function with the existing transfer unit by utilizing the gate electrode as a charge holding portion. The transfer unit's gate electrode serves dual purposes: controlling charge transfer from the photoelectric conversion unit and providing charge holding capacitance for high dynamic range imaging, thereby eliminating the need for separate capacitive coupling wiring.
Solution Approach 2:
The gate electrode of the transfer unit is designed to perform multiple functions simultaneously: it acts as both the control element for charge transfer and as the charge holding portion for capacitance adjustment. This multi-functionality reduces the overall circuit complexity while maintaining the high dynamic range imaging capability.
2Measurement precision
If capacitive coupling wiring is added to adjust charge holding capacitance of floating diffusion, then high dynamic range imaging is achieved, but manufacturing cost increases
Solution Approach 1:
The patent merges the capacitance adjustment function with the existing transfer unit by utilizing the gate electrode as a charge holding portion. The transfer unit's gate electrode serves dual purposes: controlling charge transfer from the photoelectric conversion unit and providing charge holding capacitance for high dynamic range imaging, thereby eliminating the need for separate capacitive coupling wiring.
Solution Approach 2:
The patent extracts the capacitance adjustment function from the traditional capacitive coupling wiring approach and integrates it into the transfer unit's gate electrode. This extraction eliminates the need for additional wiring and control circuits, thereby reducing manufacturing complexity and cost.
3Adaptability or versatility
If control circuit for adjusting signal to capacitive coupling wiring is added, then charge holding capacitance is adjusted, but circuit density increases
Solution Approach 1:
The transfer unit's gate electrode performs self-service by simultaneously executing charge transfer control and charge holding capacitance functions. The same electrode structure that controls the transfer process also provides the necessary capacitance, eliminating the need for separate control circuits for capacitance adjustment.
Solution Approach 2:
The patent merges the capacitance adjustment function with the existing transfer unit by utilizing the gate electrode as a charge holding portion. The transfer unit's gate electrode serves dual purposes: controlling charge transfer from the photoelectric conversion unit and providing charge holding capacitance for high dynamic range imaging, thereby eliminating the need for separate capacitive coupling wiring.
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 proposed solution enables high dynamic range imaging at lower costs by controlling floating diffusion capacitance through electrostatic coupling, improving yield and reducing manufacturing costs without adding drive interconnections or circuits.
Implementation Method 1
a capacitor configured by an electrostatic coupling between a first interconnection connected to the control node and a second interconnection arranged adjacent to the first interconnection and connected to the second charge holding portion
Data Source
AI summary
A photoelectric conversion device includes a photoelectric conversion unit that generates charge in response to incidence of light, a first charge holding portion, a second charge holding portion, a transfer unit that transfers the charge of the photoelectric conversion unit to the first charge holding portion in response to a control signal to a control node, a switch that controls a connection between the first charge holding portion and the second charge holding portion, a capacitor configured by an electrostatic coupling between a first interconnection connected to the control node and a second interconnection arranged adjacent to the first interconnection and connected to the second charge holding portion, and an output unit that outputs a signal corresponding to a potential of the first charge holding portion.