Configurable MOS Pixel Charge Domain Binning

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Solution Overview

Problem

Charge domain binning in CMOS image sensors is limited to simple and small pixels, cannot be applied to global shutter pixels, and introduces parasitic capacitance that reduces sensitivity and signal-to-noise ratio (SNR).

Innovation Solution

An array of pixels with at least two types of charge collecting capabilities, where one pixel can function as a high-capability pixel or a low-capability pixel, allowing for configurable operation to achieve high resolution or charge binning, with voltage bias control to manage the charge collecting terminals and depletion regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If charge domain binning is applied to increase sensitivity and readout speed, then sensitivity and readout speed are improved, but parasitic capacitance is introduced which reduces sensitivity and SNR

Engineering Contradiction:

Improvereadout speedVSAvoidsignal-to-noise ratio

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The pixel array is segmented into multiple independently controllable pixel units, each capable of autonomous charge collection and transfer. This segmentation allows selective activation of pixels based on lighting conditions, enabling binning operations only where needed while maintaining low noise in other regions, thus improving SNR while achieving fast readout.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic control of pixel states through voltage biasing, allowing pixels to switch between active charge collection mode and inactive mode. This dynamic configurability enables adaptive binning where pixels can be selectively activated or deactivated based on scene requirements, optimizing both sensitivity and SNR for different imaging conditions.

Inventive Principle:

Principle #15Dynamics

2Reliability

If charge domain binning is applied to increase sensitivity, then sensitivity is improved, but the method can only be applied to simple and small pixels, limiting adaptability

Engineering Contradiction:

ImprovesensitivityVSAvoidapplicability to different pixel types

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent designs a universal pixel unit architecture that can function in multiple modes: as a standalone pixel for high-resolution imaging, as part of a binned group for sensitivity enhancement, or in global shutter mode for motion-free capture. The same pixel unit structure supports all these functions through configurable control signals, eliminating the need for different pixel designs for different applications.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If all pixels are configured with high charge collecting capability for high resolution imaging, then image resolution is improved, but readout power consumption increases

Engineering Contradiction:

Improveimage resolutionVSAvoidreadout power consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies local quality control by enabling only the specific pixel units that need to be read out at any given time, while keeping other pixels in a low-power standby state. This localized activation approach allows high-resolution imaging when needed while dramatically reducing power consumption during continuous operation, as pixels can be selectively switched on and off based on the current frame's requirements.

Inventive Principle:

Principle #3Local quality

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

Enables efficient charge domain binning with increased sensitivity and SNR, allowing for flexible operation between high-resolution and low-power modes, and supports larger pixel arrays without compromising sensitivity.

Implementation Method 1

collecting charges generated by radiation impinging on the substrate

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

configurable as a pixel of the first type (more collecting) or as a pixel of the second type (less collecting) under control of a voltage bias to be applied to the photoreceptor charge collecting terminal

Methodology Applied

Scientific EffectElectric field control: Electric Field

Data Source

PatentUS11463634B2Charge domain binning in a MOS pixel

Publication Date: 2022.10.04 CAELESTE CVBA

AI summary

An array of pixels for charge domain binning in a CMOS image sensor, to increase the readout sensitivity of such a sensor. The array of pixels comprises at least two pixels in a common substrate. At least one of said pixels is configured or configurable to function as a pixel of a first type with a first, higher, charge collecting capability, for collecting charges generated by radiation impinging on the substrate. At least another one of said pixels is configurable to function as pixel of a second type, with a second, reduced, charge collecting capability, and as a pixel of the first type.