Solid-State Image Sensor Reset Circuit for Stable Address Events
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Solution Overview
Problem
Asynchronous solid-state image sensors, such as dynamic vision sensors, face challenges with detection accuracy due to voltage variations caused by switching noise in the reset transistor during initialization, which affects the detection of address events in applications like traffic monitoring and robotics.
Innovation Solution
The proposed solution involves an electronic circuit with a capacitance that supplies charge corresponding to pixel voltage variations, a reset transistor for initializing the output voltage, and a charge supply unit that adjusts the voltage to an initial value, reducing leakage current and improving detection accuracy by offsetting voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reset transistor is used to initialize the differentiating circuit, then the output voltage can be controlled to an initial value, but switching noise (feedthrough) is generated causing voltage variations that reduce detection accuracy
Solution Approach 1:
A capacitance element is introduced as an intermediary between the reset transistor and the output terminal. The reset transistor switches the capacitance to initialize the output voltage to a reference level, while the capacitance isolates the switching noise from directly affecting the output terminal. This mediator allows the reset function to be performed while blocking the feedthrough noise path.
Solution Approach 2:
The capacitance element is pre-charged to a reference voltage level before the reset operation. When the reset transistor switches, the capacitance provides a buffered charge reservoir that cushions against voltage variations at the output terminal. This prior preparation of the capacitance state prevents sudden voltage spikes or drops that would otherwise occur during the reset switching action.
2Reliability
If the reset transistor switches during initialization, then the output voltage is reset to initial value, but leakage current occurs affecting voltage stability
Solution Approach 1:
The capacitance element serves as an intermediary that blocks the direct path of leakage current from the reset transistor to the output terminal. By charging the capacitance to the reference voltage and using it as a buffer, the leakage current is isolated from the output, maintaining voltage stability even during and after the reset operation.
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 detection accuracy of address events by stabilizing the output voltage and reducing leakage current, thereby improving the performance of solid-state image sensors in fast-paced environments.
Implementation Method 1
a capacitance that supplies a charge corresponding to an amount of variation in a predetermined pixel voltage to a predetermined input terminal
Implementation Method 2
a reset transistor that supplies one of a positive charge or a negative charge during a predetermined period to control the output voltage to an initial value
Data Source
AI summary
To suppress voltage variations due to transistor switching noise in a solid-state image sensor including a transistor that initializes a differentiating circuit.A capacitance supplies a charge corresponding to an amount of variation in a predetermined pixel voltage to a predetermined input terminal. A voltage output unit outputs, as an output voltage, a voltage corresponding to an input voltage at the input terminal from a predetermined output terminal. A reset transistor supplies one of a positive charge or a negative charge during a predetermined period to control the output voltage to an initial value in a case where initialization is instructed. A charge supply unit supplies the other of the positive charge or the negative charge when the predetermined period elapses.