Receiver Optical Sub-Assembly Ground Filtering for EMI Crosstalk

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Solution Overview

Problem

Optical communications networks face significant electromagnetic crosstalk interference in complex radiation environments, particularly in high-speed systems like 10G PON and 5G Wi-Fi, which affects signal sensitivity and system performance.

Innovation Solution

A receiver optical sub-assembly design with direct and alternating current grounding through filter components, isolating and absorbing electromagnetic crosstalk signals from various sources, including ground and power terminals, to improve anti-electromagnetic interference performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the receiver optical sub-assembly is placed in a complex electromagnetic radiation environment to meet high-speed communication requirements, then network throughput and bandwidth are improved, but electromagnetic crosstalk interference increases

Engineering Contradiction:

Improvenetwork throughputVSAvoidelectromagnetic crosstalk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces filter components as intermediary elements between the trans-impedance amplifier and the external ground. These filter components act as mediators that selectively pass desired signals while blocking electromagnetic crosstalk interference, thus resolving the contradiction between maintaining high-speed communication performance and reducing electromagnetic interference

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The grounding system is segmented into multiple paths: a first ground terminal directly connected to external ground for DC grounding, and a second ground terminal connected through filter components for AC grounding. This segmentation allows different frequency components to be handled differently, enabling high-speed signal transmission while filtering out electromagnetic crosstalk

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If direct current grounding is implemented for the trans-impedance amplifier, then signal reference stability is improved, but alternating current electromagnetic interference is not effectively filtered

Engineering Contradiction:

Improvesignal reference stabilityVSAvoidalternating current electromagnetic interference

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The grounding system is divided into two functional segments: a first ground terminal providing direct DC grounding for signal reference stability, and a second ground terminal providing filtered AC grounding through filter components. This segmentation enables simultaneous achievement of stable signal reference and effective AC electromagnetic interference filtering

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different grounding characteristics are applied to different terminals: the first ground terminal provides low-impedance direct grounding for DC stability, while the second ground terminal provides frequency-selective filtering for AC interference rejection. Each terminal has optimized local grounding quality suited to its specific function

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

The design effectively filters out electromagnetic crosstalk, optimizing signal integrity and reducing interference, thereby enhancing the performance of optical network devices in challenging electromagnetic environments.

Implementation Method 1

a photodiode, configured to convert an optical signal into an electrical signal

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

The first filter component can filter out an electromagnetic crosstalk signal from a ground

Methodology Applied

Scientific EffectElectromagnetic filtering: Filter (electronic)

Data Source

PatentUS12470303B2Receiver optical sub-assembly, bi-directional optical sub-assembly, optical module, and optical network device

Publication Date: 2025.11.11 HUAWEI TECH CO LTD

AI summary

This application provides example receiver optical sub-assemblies, example bi-directional optical sub-assemblies, and example optical network devices. One example receiver optical sub-assembly includes a photodiode, a trans-impedance amplifier, and a first filter component. The photodiode is configured to convert an optical signal into an electrical signal, a positive electrode of the photodiode is connected to an input terminal of the trans-impedance amplifier, and a negative electrode of the photodiode is configured to connect to a power supply. The trans-impedance amplifier is configured to amplify the electrical signal output by the photodiode, where a power terminal of the trans-impedance amplifier is configured to connect to a power supply, and a first ground terminal of the trans-impedance amplifier is configured to connect to an external ground.