Binary Pixel Circuit Noise Immunity via Initialization
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Solution Overview
Problem
Binary pixel image sensors are susceptible to random device noise and fixed pattern noise due to mismatches across pixels, which affect image quality.
Innovation Solution
The binary pixel image sensor incorporates binary pixel circuits with a light-detecting element, a binary amplifier, and initialization circuitry, where the initialization circuitry sets an input voltage offset relative to the switching threshold, increasing noise immunity by directly coupling the photodiode to the binary amplifier and resetting the input voltage to the switching threshold, thereby reducing noise caused by intervening components and threshold voltage differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If binary pixel circuits are used to improve dynamic range, then dynamic range is improved, but random device noise and fixed pattern noise increase
Solution Approach 1:
The patent extracts and removes the source of noise by directly coupling the photodiode to the binary amplifier, eliminating intervening components that generate random device noise. This extraction approach separates the noise-generating elements from the signal path while preserving the binary circuit's dynamic range advantage.
Solution Approach 2:
The initialization circuitry performs preliminary action by resetting the input voltage to a defined threshold level before each measurement cycle. This preliminary resetting action eliminates fixed pattern noise caused by threshold voltage mismatches between pixels, ensuring consistent starting conditions for all binary pixel circuits.
2Object-affected harmful factors
If initialization circuitry resets input voltage to switching threshold, then fixed pattern noise is reduced, but device complexity increases
Solution Approach 1:
The initialization circuitry is merged with the binary pixel circuit structure, sharing common elements such as the input node and feedback pathways. This integration approach reduces overall device complexity compared to having separate initialization circuits for each pixel, while still achieving fixed pattern noise reduction through voltage resetting.
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 enhances the immunity of the binary pixel image sensor to random noise and fixed pattern noise, improving image quality by reducing noise interference and maintaining accurate light detection thresholds across pixels.
Implementation Method 1
a light-detecting element (e.g. a photodiode), a binary amplifier
Data Source
AI summary
An integrated-circuit image sensor that includes an array of pixel regions composed of binary pixel circuits. Each binary pixel circuit includes a binary amplifier having an input and an output. The binary amplifier generates a binary signal at the output in response to whether an input voltage at the input exceeds a switching threshold voltage level of the binary amplifier. A light-detecting element of the binary pixel circuit is coupled to the input of the binary amplifier. Initialization circuitry of the binary pixel circuit is coupled to the input of the binary amplifier. The initialization circuitry sets the input voltage to a level that is offset relative to the switching threshold voltage level of the binary amplifier by an offset voltage amount, the offset voltage amount representing a threshold amount of light incident on the light detecting element.