Demodulation Pixel With Drift Field For High Speed Sensitivity

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Solution Overview

Problem

Existing pixel devices face challenges in achieving high sensitivity and high demodulation speed simultaneously due to limitations in charge transport processes, leading to reduced performance at high frequencies and increased parasitic capacitances.

Innovation Solution

A pixel device with a semiconductor substrate that utilizes a lateral, static drift field for fast charge transport, featuring a detection region with a large photo-sensitive area and a demodulation region with small, non-photo-sensitive conduction channels, allowing for high-frequency demodulation without sensitivity loss and reduced parasitic capacitances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the photo-detection region is enlarged to increase sensitivity, then sensitivity is improved, but parasitic capacitances increase and transport paths lengthen, restricting the device to high-frequencies

Engineering Contradiction:

ImprovesensitivityVSAvoiddemodulation speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The device is segmented into a large photo-detection region for high sensitivity and a separate small demodulation region for fast operation. The photo-detection region collects photo-generated charges over a large area, while the demodulation region with short transport paths performs rapid sampling and demodulation, resolving the contradiction between sensitivity and speed

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A drift field is introduced as an intermediary mechanism to rapidly transport photo-generated charges from the large photo-detection region to the demodulation region. This drift field enables fast charge collection without requiring the entire device to operate at high speed, allowing both large detection area and fast demodulation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If switching gate capacities are increased to control larger photo-detection regions, then sensitivity is improved, but speed limitations are imposed by driving electronic components

Engineering Contradiction:

ImprovesensitivityVSAvoidoperating frequency

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The device separates the photo-detection function (large area) from the demodulation function (small area with fast electronics). This segmentation allows the photo-detection region to be large for sensitivity while the demodulation region maintains small gate capacities for high-speed operation, eliminating the trade-off between sensitivity and operating frequency

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If long transport paths are used to cover large photo-detection areas, then sensitivity is improved, but demodulation speed is reduced

Engineering Contradiction:

ImprovesensitivityVSAvoidcharge transport time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

A drift field is introduced as an intermediary to rapidly transport photo-generated charges from the large photo-detection region to the demodulation region. This drift field enables fast charge collection without requiring the entire device to operate at high speed, allowing both large detection area and fast demodulation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Inventive Principle:

Principle #1Segmentation

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 high-speed and high-sensitivity demodulation of optical waves up to the Gigahertz range with reduced noise and power consumption, supporting applications like 3D imaging and fluorescence measurement.

Implementation Method 1

detection means for converting the incident electromagnetic wave field into an electric signal of flowing charges

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

A pixel structure available that shows both high-sensitivity and high speed capability in terms of demodulating the impinging signal... The transfer of the photo-generated electrons over the potentially large photo-sensitive area of the detection region is mainly accomplished by a lateral, static drift field

Methodology Applied

Scientific EffectDrift field: Electric Field

Data Source

PatentUS8115158B2Device and method for the demodulation of modulated electromagnetic wave fields

Publication Date: 2012.02.14 AMS OSRAM ASIA PACIFIC PTE LTD

AI summary

A new pixel in semiconductor technology comprises a photo-sensitive detection region (1) for converting an electromagnetic wave field into an electric signal of flowing charges, a separated demodulation region (2) with at least two output nodes (D10, D20) and means (IG10, DG10, IG20, DG20) for sampling the charge-current signal at least two different time intervals within a modulation period. A contact node (K2) links the detection region (1) to the demodulation region (2). A drift field accomplishes the transfer of the electric signal of flowing charges from the detection region to the contact node. The electric signal of flowing charges is then transferred from the contact node (K2) during each of the two time intervals to the two output nodes allocated to the respective time interval. The separation of the demodulation and the detection regions provides a pixel capable of demodulating electromagnetic wave field at high speed and with high sensitivity.