Photoelectric Conversion Circuit With Threshold Voltage Compensation
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Solution Overview
Problem
Image sensors face variability in output current signals due to differences in threshold voltage uniformity of driving transistors, affecting the accuracy and stability of photoelectric conversion processes.
Innovation Solution
A photoelectric conversion circuit is designed with a driving transistor, a reset circuit, a conduction control circuit, a threshold compensation circuit, and a read control circuit, which initializes and compensates the threshold voltage of the driving transistor, allowing for stable output independent of threshold voltage variations by generating a detection current based on the photoelectrically converted operating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a driving transistor is used to convert photoelectric signal to current signal, then the photoelectric conversion function is achieved, but the output current varies due to threshold voltage differences affecting stability
Solution Approach 1:
The patent applies preliminary action by resetting the driving transistor's gate voltage to a predetermined initial value before each photoelectric conversion cycle. The reset circuit proactively prepares the transistor in a known state, eliminating the influence of threshold voltage variations before they can affect the output current stability.
Solution Approach 2:
The patent changes the electrical parameter (gate voltage) of the driving transistor dynamically. By adjusting the gate voltage through the reset circuit to compensate for threshold voltage differences, the system maintains stable output current despite variations in transistor characteristics.
2Measurement precision
If multiple control circuits are added to compensate threshold voltage, then output stability is improved, but the circuit complexity increases
Solution Approach 1:
The patent extracts and addresses only the critical issue of threshold voltage variation through a dedicated reset circuit, rather than implementing comprehensive compensation for all possible signal variations. This selective approach improves measurement precision for the dominant error source while limiting circuit complexity growth.
Solution Approach 2:
The reset circuit serves multiple functions: it initializes the driving transistor, compensates for threshold voltage variations, and prepares the circuit for the next conversion cycle. This multi-functionality achieves measurement precision improvement without proportionally increasing circuit complexity.
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 solution ensures a stable detection current output, independent of threshold voltage variations, thereby enhancing the accuracy and reliability of the photoelectric conversion process.
Implementation Method 1
a photoelectric conversion device, configured to receive incident light and generate an operating voltage after photoelectric conversion of the incident light
Data Source
AI summary
Disclosed are a photoelectric conversion circuit, a driving method, a photoelectric detection substrate, a photoelectric detection device, and a first reset circuit supplies a signal of initialization signal terminal to a gate of driving transistor in response to a signal of reset control signal terminal. A conduction control circuit conducts a photoelectric conversion device with driving transistor in response to a signal of scan signal terminal, a threshold compensation circuit conducts gate of the driving transistor and a second electrode of driving transistor in response to signal at the scan signal terminal to compensate for a threshold voltage of driving transistor. A read control circuit conducts a first power supply terminal with first and second electrodes of driving transistor with a read output terminal in response to a signal of read control signal terminal to output a threshold voltage compensated signal generated by driving transistor to the read output terminal.