Signal Isolator RC Filter Common Mode Transient Protection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Isolator devices face interference from common mode transients, which can cause signal corruption and exceed supply voltages, leading to incorrect decoding in noisy environments.

Innovation Solution

An isolator system incorporating an RC filter that distributes transient signals across various circuit paths, attenuating their effects at the receiver inputs, thereby limiting the impact of common mode transients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If isolator devices operate in noisy environments without additional protection, then device complexity is reduced, but signal corruption occurs due to common mode transients exceeding supply voltages

Engineering Contradiction:

Improvesignal decoding accuracyVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

An RC filter circuit is introduced as an intermediary component between the isolator output and the receiver input. The filter acts as a mediator that processes the differential signals and attenuates common mode transients before they reach the receiver, preventing signal corruption without requiring changes to the core isolator or receiver architecture

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protection function is segmented into a separate RC filter stage that can be independently designed and optimized. This segmentation allows the filter to handle common mode transient suppression while the main isolator and receiver focus on their primary functions of signal transmission and decoding, respectively

Inventive Principle:

Principle #1Segmentation

2Reliability

If RC filter is added to protect against common mode transients, then signal decoding accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvesignal decoding accuracyVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The RC filter uses simple, inexpensive passive components (resistors and capacitors) that can be easily implemented without adding significant complexity. These components are robust and require minimal maintenance, providing effective transient suppression at low cost and complexity

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 RC filter effectively reduces the impact of common mode transients, preventing signal corruption and ensuring accurate signal decoding by distributing transient signals and reducing voltage variations.

Implementation Method 1

an RC filter coupled between the isolator and the receiver. During operation, the filter may distribute transient signals across various circuit paths

Methodology Applied

Scientific EffectRC filtering: Filter (electronic)

Data Source

PatentUS9998301B2Signal isolator system with protection for common mode transients

Publication Date: 2018.06.12 ANALOG DEVICES INC

AI summary

An isolator system has an isolator that generates differential isolator signals and a receiver that generates digital data representative of signals received from the isolator. The system also may include an RC filter coupled between the isolator and the receiver. During operation, the filter may distribute transient signals across various circuit paths in the isolator, only some of which are coupled to the receiver inputs. Over time, the filter may attenuate transient contributions at the receiver inputs. In this manner, the filter may limit effects of these common mode transients.