Image Sensor Data-Line Hold Circuit for Faster Voltage Settling
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Solution Overview
Problem
The existing image sensor technologies face challenges in maintaining data line voltage stability during transitions from reset to light integration operations, leading to increased settle times that can reduce the operating speed of analog-to-digital converters and overall image sensor device performance.
Innovation Solution
The implementation of a voltage hold circuit that includes a capacitor, source follower, enable switch, store switch, and initialize switch, which stores and maintains a voltage level on the data line, ensuring that the data line voltage remains stable during transitions by providing a hold voltage based on the stored voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of pixels is increased to improve resolution, then the image sensor resolution is improved, but the time to read out data from the image sensor decreases
Solution Approach 1:
The voltage hold circuit performs preliminary action by storing the reset voltage on the capacitor before the light integration operation begins. This pre-stored voltage is then used to quickly restore the data line voltage after pixel output, reducing the settle time without requiring extended readout periods that would compromise resolution performance
2Stability of the object's composition
If the settle time of data line voltage is extended to improve voltage stability, then the data line voltage stability is improved, but the operating speed of analog-to-digital converter decreases
Solution Approach 1:
The voltage hold circuit performs preliminary action by storing the reset voltage on the capacitor before the light integration operation begins. This pre-stored voltage is then used to quickly restore the data line voltage after pixel output, reducing the settle time without compromising voltage stability
Solution Approach 2:
The capacitor in the voltage hold circuit acts as an intermediary element that stores the reset voltage and provides it to the data line when needed. This intermediary storage mechanism enables rapid voltage restoration without requiring extended settle times, thus maintaining both voltage stability and converter operating speed
3Stability of the object's composition
If a voltage hold circuit is added to maintain data line voltage stability, then the data line voltage stability is improved, but the device complexity increases
Solution Approach 1:
The voltage hold circuit is designed to perform multiple functions: storing reset voltage during light integration, providing hold voltage to maintain data line stability during pixel output, and enabling rapid voltage restoration. This multi-functionality reduces the need for separate circuits for each function, thereby limiting the increase in overall device complexity while achieving improved voltage stability
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 approach reduces the settle time of the data line voltage, enhancing the performance of the image sensor device by minimizing voltage variations and maintaining stability during pixel output operations.
Implementation Method 1
a capacitor that is connected between a first node and a second node
Data Source
AI summary
Disclosed is an image sensor device which includes an image pixel that outputs a reset voltage and a first data voltage through a data line, and a voltage hold circuit that is connected with the data line, stores a first voltage based on the reset voltage, and provides the data line with a second voltage based on the first voltage.