CMOS Image Sensor Vertical Signal Line Settling Time Reduction
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Solution Overview
Problem
In CMOS image sensors, the settling time of the vertical signal line to reach the reset level signal is excessively long when the pixel signal level is low, hindering high-speed read operations.
Innovation Solution
Incorporating a pull-up circuit that increases the potential of the vertical signal line during the read operation of pixels, utilizing transistors and switches to rapidly settle the signal line to the reset level, thereby reducing the settling time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel signal level is low, then the A/D conversion can be performed, but the settling time of the vertical signal line becomes excessively long
Solution Approach 1:
The pull-up circuit is activated in advance during the reset period to pre-charge the vertical signal line to a high potential level before the read operation begins. This preliminary action ensures that when the pixel signal is read, the signal line can quickly settle to the required level without excessive delay, thus reducing the settling time while maintaining A/D conversion accuracy.
2Productivity
If the read operation speed is increased, then the frame rate can be improved, but the settling time requirement becomes more stringent
Solution Approach 1:
By activating the pull-up circuit during the reset period before the read operation, the vertical signal line is pre-charged to a high potential level. This preliminary action reduces the settling time required during the actual read operation, enabling faster read speeds and higher frame rates without compromising signal settling accuracy.
3Loss of time
If the potential of the vertical signal line is increased using a pull-up circuit, then the settling time is reduced, but the circuit complexity increases
Solution Approach 1:
The pull-up circuit is designed to serve multiple functions: it acts as a signal line charger during the reset period to reduce settling time, and can be integrated with existing circuit components. This multi-functional design minimizes the increase in overall circuit complexity while achieving the desired settling time reduction.
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 significantly reduces the read operation period and enhances the frame rate by ensuring quicker A/D conversion and simultaneous read and reset operations without increasing consumption current.
Implementation Method 1
a circuit that increases a potential of the vertical signal line at the time of starting a read operation of the pixels
Data Source
AI summary
The present disclosure relates to a solid-state image sensing apparatus, a control method, and an electronic device capable of reducing a settling time of a vertical signal line at the time of a read operation of pixels. A column processing unit A/D converts pixel signals of a plurality of pixels. A vertical signal line feeds the pixel signals output from the pixels to the A/D converter. A pull-up circuit increases a potential of the vertical signal line at the time of starting a read operation of the pixels. For example, the present disclosure can be applied to a CMOS (Complementary Metal-Oxide Semiconductor) image sensor that performs an interleaving operation or the like.