Solid-state imaging device with dual feedback amplifiers for kTC noise reduction
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Solution Overview
Problem
Existing solid-state imaging devices face challenges in achieving high-speed frame rates for continuous image capturing or video capturing with higher pixel counts due to kTC noise from reset transistors, which is exacerbated by techniques that reduce noise proportionally with reset time, and the inability to reset pixel signals and electronic shutter rows in parallel when using single feedback amplifiers.
Innovation Solution
A solid-state imaging device is designed with a pixel unit featuring two types of pixels connected to separate feedback amplifiers, allowing for parallel operation and reduced noise through the use of first and second connection-type pixels with specific transistor configurations and signal line connections, enabling simultaneous reset and read operations across multiple rows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a reset transistor is turned OFF gradually (soft reset technique) or a single feedback amplifier is connected to each column, then kTC noise is reduced, but pixel read time increases and frame rate decreases
Solution Approach 1:
The pixel array is divided into two independent sets: first connection-type pixels connected to first feedback amplifiers and second connection-type pixels connected to second feedback amplifiers. Each feedback amplifier operates independently to reset its connected pixels, enabling parallel processing that reduces total reset time while maintaining noise reduction effectiveness.
Solution Approach 2:
The patent combines the reset operations of read rows and electronic shutter rows into a parallel processing framework. Both row types can be reset simultaneously using the dual feedback amplifier configuration, effectively doubling the reset throughput compared to sequential processing while maintaining the noise reduction benefits of feedback amplifiers.
2Object-affected harmful factors
If a single feedback amplifier is connected to each column, then kTC noise is reduced, but parallel resetting of pixel signals and electronic shutter rows becomes impossible
Solution Approach 1:
The pixel array is segmented into two independent operational groups with separate feedback amplifier pathways. First connection-type pixels use first feedback amplifiers while second connection-type pixels use second feedback amplifiers, allowing independent and parallel processing of different pixel types without interference.
Solution Approach 2:
The dual feedback amplifier configuration provides universal reset capability for both read rows and electronic shutter rows simultaneously. Each feedback amplifier type can handle its designated pixel type, and both operations proceed in parallel, achieving multi-functionality in the readout system.
3Object-affected harmful factors
If reset time is increased to reduce kTC noise proportionally, then noise decreases, but pixel read time increases and high-speed capturing becomes difficult
Solution Approach 1:
By dividing the pixel array into two independently processed groups with separate feedback amplifiers, the total reset operation is parallelized. Each feedback amplifier processes its connected pixels simultaneously, reducing the overall reset time by approximately half compared to sequential processing, thereby maintaining high frame rates while preserving noise reduction.
Solution Approach 2:
The dual feedback amplifier system enables continuous parallel reset operations for both read rows and electronic shutter rows. While one set of pixels is being reset, the other set can be simultaneously processed, eliminating idle time and maintaining continuous productive operation throughout the frame cycle.
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 reduces noise and allows for continuous high-speed image capturing with higher pixel counts by shortening pixel read periods and enabling parallel operation of read and electronic shutter rows, thereby improving image quality and frame rate.
Implementation Method 1
a photoelectric conversion unit such as a layered film
Data Source
AI summary
A pixel unit included in a sensor chip includes: a first pixel connected to a first feedback amplifier which is connected to a first column signal line as an input line and a first reset drain line as an output line; and a second pixel connected to a second feedback amplifier which is connected to a second column signal line as an input line and a second reset drain line as an output line. A drain of a reset transistor of the first pixel is connected to the first reset drain line, a drain of a reset transistor of the second pixel is connected to the second reset drain line, a source of an amplifying transistor of the first pixel is connected to the first column signal line, and a source of an amplifying transistor of the second pixel is connected to the second column signal line.