Image Sensor Compensation Circuit for Noise and Power
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Solution Overview
Problem
Image sensors face challenges in reducing power consumption and increasing size while effectively compensating for both horizontal noise and power noise in their output signals and ramp voltage signals.
Innovation Solution
The image sensor incorporates a first compensation circuit to address horizontal noise and a second compensation circuit to address power noise, both of which are integrated with a readout circuit that includes transistors connected in parallel to calibrate the output signals and ramp voltage signals using compensation voltage signals generated by these circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple compensation circuits are added to compensate for both horizontal noise and power noise, then noise characteristics are improved, but device complexity and power consumption increase
Solution Approach 1:
The patent combines multiple compensation circuits into a single integrated compensation circuit that performs both horizontal noise compensation and power noise compensation functions. The compensation circuit includes a first compensation unit for horizontal noise and a second compensation unit for power noise, merging previously separate functions into one unified structure, thereby reducing device complexity while maintaining noise compensation effectiveness.
Solution Approach 2:
The compensation circuit is designed with multi-functionality to handle different types of noise (horizontal noise and power noise) using a single circuit structure. The circuit can selectively activate different compensation units based on the noise type, making the system more versatile and reducing the need for separate dedicated circuits for each noise type.
2Reliability
If multiple compensation circuits are added to compensate for both horizontal noise and power noise, then noise characteristics are improved, but power consumption increases
Solution Approach 1:
The compensation circuit operates periodically rather than continuously, activating compensation units only when noise compensation is needed. The circuit uses control signals to selectively enable the first compensation unit for horizontal noise and the second compensation unit for power noise, reducing overall power consumption while maintaining effective noise compensation when required.
Solution Approach 2:
The compensation circuit employs dynamic operation where the compensation units can be selectively activated or deactivated based on operating conditions. The circuit adapts its power consumption by enabling only the necessary compensation functions at any given time, rather than running all compensation circuits continuously, thus reducing power usage while maintaining noise compensation effectiveness.
3Reliability
If compensation circuits are added to reduce noise, then noise characteristics are improved, but the size of the image sensor increases
Solution Approach 1:
The compensation circuit is nested within the existing readout circuit structure of the image sensor. The first compensation unit and second compensation unit are integrated into the signal processing path without requiring separate external circuits, allowing the compensation functionality to be embedded within the existing sensor architecture and minimizing the increase in overall sensor size.
Solution Approach 2:
The patent implements compensation functions in the electrical signal domain rather than requiring additional physical space in the optical path or sensor array. By processing noise compensation in the electrical domain through integrated circuits, the solution adds minimal physical footprint while effectively reducing noise in the output signals.
Data Source
AI summary
An image sensor includes a unit pixel, a first compensation circuit generating a first compensation voltage signal to compensate for horizontal noise corresponding to a variation in an input signal of a horizontal line coupled to the column line, a second compensation circuit generating a second compensation voltage signal to compensate for power noise corresponding to a variation in a power supply voltage, and a readout circuit including a first transistor, having a gate connected to an output terminal of the first compensation circuit, and a second transistor, connected to the first transistor in parallel, having a gate connected to an output terminal of the second compensation circuit, the readout circuit being configured to calibrate at least one of an output signal of the unit pixel and a ramp voltage signal, output by a ramp generator, using the first compensation voltage signal and the second compensation voltage signal.