Frequency Detection Pixel With Capacitive Noise Averaging

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Solution Overview

Problem

Existing frequency detection pixels for light signals, particularly those using FMCW methods, are hindered by photon noise, which interferes with photoconversion and degrades the quality of both frequency detection and visible light image capture.

Innovation Solution

The proposed pixel design incorporates multiple acquisition channels with non-pinned photodiodes, capacitive elements for noise averaging, and a control circuit to manage node potentials, effectively reducing photon noise and enhancing signal quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If frequency detection pixels are used to detect infrared signals, then frequency detection capability is improved, but the quality of visible light image detection deteriorates

Engineering Contradiction:

Improvefrequency detection accuracyVSAvoidvisible light image quality

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The pixel is divided into multiple acquisition channels (first channel with first photodiode for infrared frequency detection, second channel with second photodiode for visible light detection). This segmentation allows each channel to specialize in its detection function, enabling the pixel to perform both infrared frequency detection and visible light imaging simultaneously without mutual interference, thus resolving the contradiction between frequency detection accuracy and visible light image quality

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If photoconversion is performed in frequency detection pixels, then frequency detection is enabled, but photon noise interferes with the useful signal

Engineering Contradiction:

Improvefrequency detection capabilityVSAvoidphoton noise

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

Multiple acquisition channels are merged into a single pixel structure, where the first photodiode and second photodiode share the same pixel infrastructure including readout circuits and control logic. This merging allows the pixel to simultaneously perform infrared frequency detection and visible light detection while using common resources, improving frequency detection capability without proportionally increasing noise, as the channels can be processed and differentiated in the readout stage

Inventive Principle:

Principle #5Merging (Combining)

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 design significantly reduces noise components relative to the useful signal, improving the accuracy of frequency detection and maintaining image quality in mixed infrared and visible light environments.

Implementation Method 1

the photoconversion that takes place in these pixels to obtain a photo-current at the frequency of the signal received

Methodology Applied

Scientific EffectPhotoconversion: Photoelectric Effect

Implementation Method 2

a capacitive element coupling the photodiode to the first node

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS20250063265A1Frequency detection pixel

Publication Date: 2025.02.20 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A pixel including a first node, a second node configured to receive a first DC potential, and a plurality of acquisition channels each including: a photodiode adapted to detect radiation in a first wavelength range; a capacitive element coupling the photodiode to the first node; and a resistive element coupling a first terminal of the photodiode to the second node.