Solid-State Imaging Device Column Power Supply Noise Isolation
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Solution Overview
Problem
Conventional CMOS solid-state imaging devices face image quality degradation due to external noise in the power supply voltage and noise sneaking between columns, which affects the image quality by introducing noise into readout signals and causing horizontal line noise.
Innovation Solution
A solid-state imaging device with a plurality of pixel circuits arranged in rows and columns, featuring unit power supply circuits that generate a second power supply voltage from a first power supply voltage based on a reference voltage, and a regulator circuit that maintains a constant reference voltage, with each unit power supply circuit provided for each column or pixel circuit to supply the second power supply voltage to amplifier transistors, thereby reducing noise influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common power supply line is used for all pixel circuits, then device complexity is reduced, but noise from external power supply variations and internal circuit operations affects all columns, degrading image quality
Solution Approach 1:
The power supply system is segmented into multiple independent unit power supply circuits, each serving a specific column or pixel circuit. This segmentation isolates noise sources so that variations in one column's power supply do not affect other columns, thereby reducing horizontal line noise while maintaining manageable device complexity through modular design
Solution Approach 2:
Each unit power supply circuit is tailored to serve its specific local region (column or pixel circuit), providing locally optimized power supply with appropriate noise filtering and regulation. This local quality approach ensures that each region receives power adapted to its specific noise environment and operational requirements
2Object-affected harmful factors
If unit power supply circuits are provided for each column or pixel circuit, then noise isolation between columns is improved, but device complexity increases
Solution Approach 1:
The power supply system is divided into multiple independent unit power supply circuits, each serving a specific column or pixel circuit. This segmentation isolates noise sources so that variations in one column's power supply do not affect other columns, thereby reducing horizontal line noise while maintaining manageable device complexity through modular design
Solution Approach 2:
The unit power supply circuits are designed with universal functionality to handle multiple tasks: voltage regulation, noise filtering, and power distribution. By making each unit multi-functional, the overall system achieves effective noise isolation without requiring additional separate circuits for each function, thus controlling device complexity
3Device complexity
If external power supply voltage is directly supplied to pixel circuits, then device complexity is reduced, but external noise is directly introduced into pixel signals, degrading image quality
Solution Approach 1:
Unit power supply circuits serve as intermediary components between the external power supply and the pixel circuits. These intermediaries perform voltage regulation and noise filtering, preventing external noise from directly reaching the pixel circuits while maintaining the simplicity of external power supply connection
Solution Approach 2:
Each unit power supply circuit is self-contained with built-in noise filtering and voltage regulation capabilities. The circuits serve themselves by automatically regulating their own power supply voltage and rejecting external noise, eliminating the need for additional external noise filtering components
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
The solution effectively reduces image quality degradation caused by external noise in the power supply line and noise sneaking between columns, stabilizing the pixel signal voltage and improving image quality by isolating the second power supply voltage from variations in the first power supply voltage.
Implementation Method 1
a regulator circuit that generates the reference voltage that is constant
Implementation Method 2
a plurality of unit power supply circuits that generate a second power supply voltage from a first power supply voltage based on a reference voltage and supply the second power supply voltage to amplifier transistors
Data Source
AI summary
A solid-state imaging device includes: a plurality of pixel circuits arranged in rows and columns; a plurality of unit power supply circuits that generate a second power supply voltage from a first power supply voltage based on a reference voltage and supply the second power supply voltage to amplifier transistors provided in the plurality of pixel circuits; and a regulator circuit that generates the reference voltage that is constant. Each of the unit power supply circuits is provided for a corresponding one of the columns of the plurality of pixel circuits or for a corresponding one of the pixel circuits, and supplies the second power supply voltage to the amplifier transistors in the pixel circuits that belong to the corresponding one of the columns or to the amplifier transistor in the corresponding one of the pixel circuits.