Pixel Circuit Voltage Swing Noise Reduction
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Solution Overview
Problem
Existing pixel circuits are limited by supply voltage levels and introduce significant read-out noise, affecting their performance.
Innovation Solution
A pixel circuit design comprising a photodiode, comparator circuit, capacitor, and switch circuits that operate without additional supply voltage, reducing noise by minimizing the number of noise-introducing components and using a ramp signal to generate output signals, allowing for improved voltage transitions and detection information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional supply voltage is used to overcome voltage level limitations, then voltage swing range is improved, but device complexity and noise introduction increase
Solution Approach 1:
The patent removes the additional supply voltage terminal from the pixel circuit architecture, extracting the unnecessary component that would increase complexity. The solution achieves voltage swing flexibility through existing supply voltage by using capacitor charging/discharging mechanisms and switch circuit configurations, thereby reducing device complexity while maintaining adaptability.
Solution Approach 2:
The existing supply voltage terminal is made multi-functional, serving both as the power source and as a reference for voltage swings. The capacitor and switch circuits enable the same supply voltage to provide both biasing and voltage swing capability, eliminating the need for separate additional supply voltage terminals.
2Adaptability or versatility
If more components are added to improve voltage swing capability, then voltage range is improved, but read-out noise increases
Solution Approach 1:
The patent extracts and removes components that would introduce additional read-out noise. By using only the essential switch circuits and capacitor with the existing supply voltage, the design minimizes the number of active components that could generate noise, thereby reducing read-out noise while maintaining voltage range capability.
Solution Approach 2:
The capacitor and switch circuits utilize the existing supply voltage to generate voltage swings through natural charging and discharging processes, without requiring additional active components that would introduce noise. The system serves itself by using the same supply voltage for both biasing and signal generation.
3Power
If supply voltage level is increased to overcome limitations, then voltage swing capability is improved, but the circuit introduces more noise
Solution Approach 1:
The patent changes the operational parameters of the existing supply voltage by using capacitor charging/discharging dynamics and switch timing control. This allows the same supply voltage level to provide enhanced voltage swing capability through temporal and dynamic parameter manipulation, rather than increasing the voltage level itself, thereby avoiding noise introduction.
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 enhances the pixel circuit's performance by reducing reliance on supply voltage limitations and minimizing read-out noise, thereby improving overall performance without introducing unwanted side effects.
Implementation Method 1
The photodiode is arranged to accumulate charges in response to incident radiation, to generate a photodiode signal
Data Source
AI summary
A pixel circuit is provided. The pixel circuit may comprise a photodiode, a comparator circuit, a capacitor, a first switch circuit, a second switch circuit and a third switch circuit. The photodiode is arranged to accumulate charges in response to incident radiation, to generate a photodiode signal. The comparator circuit is arranged to generate an output signal according to a voltage level of a specific node within the pixel circuit during a read-out phase of the pixel circuit. The capacitor is coupled between a control voltage terminal of the pixel circuit and the specific node, the first switch circuit is coupled between the photodiode and the specific node, the second switch circuit is coupled between the specific node and an output terminal of the pixel circuit, and the third switch circuit is coupled between the output terminal and the comparator circuit.