Junction Isolated Clamp Circuit for ESD Crosstalk Reduction

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Solution Overview

Problem

Aerospace electronic systems face interconnection failures due to moisture, temperature cycling, and vibration, leading to issues like signal crosstalk caused by circulating currents through electrostatic discharge protection circuits, which existing ESD protection methods fail to adequately address.

Innovation Solution

The implementation of a junction isolated clamp circuit and method that directs energy between power circuits and signal nodes based on reference voltages to prevent collector terminals from having lower voltages, thereby reducing or preventing signal crosstalk and providing effective ESD protection by using transistors and diodes to manage transient events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If traditional ESD protection circuits are used, then electrostatic discharge protection is provided, but circulating currents cause signal crosstalk during interconnection failures

Engineering Contradiction:
ImproveESD protectionVSAvoidsignal crosstalk
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The ESD protection circuit is segmented into multiple independent clamp circuits, each protected by its own isolation mechanism. The isolation circuitry divides the protection function into separate segments that can operate independently, preventing circulating currents from affecting the entire system during interconnection failures.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

An isolation circuit acts as an intermediary between the ESD protection clamp circuits and the signal lines. This intermediary component blocks the path for circulating currents while still allowing the clamp circuits to provide ESD protection, thereby preventing signal crosstalk during interconnection failures.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If interconnection reliability is improved to prevent failures, then signal crosstalk is reduced, but device complexity increases

Engineering Contradiction:
Improveinterconnection reliabilityVSAvoidcircuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The isolation function is extracted as a separate, dedicated circuit component rather than being integrated into the existing ESD protection or interconnection structures. This extracted isolation circuit specifically addresses the circulating current problem without requiring redesign of the entire interconnection system.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Isolation circuitry is applied locally at critical points where interconnection failures could cause signal crosstalk, rather than requiring universal reinforcement of all interconnections. This localized approach provides necessary protection while minimizing overall device complexity.

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If clamp circuits are added for ESD protection, then ESD surge protection is improved, but device complexity increases

Engineering Contradiction:
ImproveESD surge protectionVSAvoidcircuit complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The clamp circuits are designed to serve multiple functions: providing ESD surge protection during normal operation and working in conjunction with the isolation circuitry to prevent signal crosstalk during interconnection failures. This multi-functionality reduces the need for separate dedicated circuits for each protection mechanism.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution effectively reduces signal crosstalk and provides robust ESD protection in aerospace systems by ensuring that collector terminals maintain appropriate voltages, even during transient events, thereby enhancing the reliability of electronic components in challenging environments.

Implementation Method 1

the first clamp circuit to direct energy from the signal node to the first power circuit in response to a transient event resulting in a voltage at the signal node being lower than a second reference voltage

Methodology Applied
Scientific EffectTransient event response through voltage threshold comparison:

Data Source

PatentEP2779239B1Methods and apparatus to provide transient event protection for circuits
Publication Date: 2019.08.14 THE BOEING CO
  • EP2779239B1 patent drawingFigure 1
  • EP2779239B1 patent drawingFigure 2A~2B
  • EP2779239B1 patent drawingFigure 3A~3B

AI summary

Methods and apparatus to provide transient event protection for circuits are disclosed. An example apparatus includes a first clamp circuit. The first power circuit provides a first reference voltage. The first clamp circuit directs energy from a signal node to the first power circuit in response to a transient resulting in a voltage at the signal node being lower than a second reference voltage. The apparatus also includes a second clamp circuit. The second clamp circuit includes a transistor. A collector terminal of the transistor is prevented from having a lower voltage than the second reference voltage. A second power circuit provides the second reference voltage, which is lower than the first reference voltage. The second clamp circuit directs energy from the signal node to the second power circuit in response to a transient resulting in the voltage at the signal node being higher than the first reference voltage.