Reset-Switched Amplifier Circuit for False Event Suppression
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Solution Overview
Problem
Image sensor devices, particularly event-based sensors like dynamic vision sensors, suffer from reliability issues due to leakage currents and device noise in amplifiers, leading to unintended false events.
Innovation Solution
The amplifier design includes a first and second capacitor, an amplifying element, a current bias source, and reset switches controlled by a reset bias generator, which prevent leakage currents and device noise by resetting the floating node and output node to a reset voltage, thereby improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional amplifier components (converter and amplifier) are used in event-based sensors, then the sensor can generate electrical signals from incident light, but leakage current and device noise occur causing unintended false events
Solution Approach 1:
The reset switch is activated before the amplifier operates to pre-clear any accumulated charge or noise on the floating diffusion node. This preliminary reset action prevents leakage current and device noise from building up during the amplification process, thereby eliminating false events before they can occur.
Solution Approach 2:
The invention changes the voltage parameter of the floating diffusion node by applying a reset voltage through the reset switch. This parameter change (voltage reset) clears any unwanted charge accumulation and resets the node to a known state, preventing leakage current and noise from causing false events.
2Productivity
If the amplifier operates continuously to amplify input voltage changes, then event detection capability is maintained, but leakage current accumulates causing false events
Solution Approach 1:
The reset switch operates periodically rather than continuously, being activated at specific intervals to clear accumulated charge and noise. This periodic reset action maintains event detection capability while preventing leakage current accumulation that would cause false events, resolving the contradiction between continuous operation and reliability.
Data Source
AI summary
An amplifier includes a first capacitor connected between an input node and a floating node, a second capacitor connected between the floating node and an output node, an amplifying element connected between a power supply voltage and the output node and operating in response to a voltage level of the floating node, a current bias source connected between the output node and a ground voltage, a first reset switch connected between the floating node and an intermediate node and operating in response to a reset bias, a second reset switch connected between the intermediate node and the output node and operating in response to the reset bias, and a reset bias generator circuit that outputs the reset bias in response to a reset signal. The reset bias is one of a reset voltage of the intermediate node, the power supply voltage, and the ground voltage.