Series ESD Circuit for High-Speed Interface Impedance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ESD protection systems for high-speed interfaces introduce impedance discontinuities and fail to effectively divert ESD current away from the Device Under Protection (DUP) due to parasitic resistance and inductance, compromising signal integrity and requiring complex PCB tuning.
Innovation Solution
A series ESD configuration where the Device Under Test (DUT) is in series with the DUP, utilizing parasitic series inductance and resistance to divert ESD current, combined with flow-through routing and integrated ESD stages to eliminate impedance discontinuities and simplify PCB design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional shunt-type ESD clamps are used in parallel with the DUP, then ESD protection is provided, but impedance discontinuity is introduced in the frequency band of interest
Solution Approach 1:
The patent inverts the conventional parallel ESD clamp architecture to a series configuration. Instead of placing the ESD clamp in parallel with the DUP as done conventionally, the ESD clamp is placed in series with the signal line, fundamentally changing the protection mechanism while eliminating the associated impedance discontinuity problems.
Solution Approach 2:
The patent changes the topological parameter of the ESD clamp connection from parallel to series. This parameter change transforms the ESD protection mechanism while simultaneously resolving the impedance discontinuity issue that plagues conventional parallel configurations in high-speed interfaces.
2Reliability
If series parasitic resistance and inductance are present in the DUT, then ESD current diversion is hindered, but the DUP remains exposed to ESD threat
Solution Approach 1:
The patent extracts the ESD clamp from its conventional parallel position and relocates it to a series position in the signal path. This extraction and repositioning allows the ESD clamp to actively divert ESD current away from the DUP by providing an alternative current path through the series configuration, overcoming the limitations of parasitic resistance and inductance.
Solution Approach 2:
The series ESD clamp acts as an intermediary element between the ESD threat and the DUP. By positioning the ESD clamp in series, it mediates the ESD current flow, forcing the current to pass through the clamp which then diverts it away from the DUP, effectively protecting the sensitive device.
3Reliability
If parasitic capacitive load of the ESD clamp circuit is added, then transmission line impedance is reduced, but complex PCB tuning is required to offset impedance discontinuity
Solution Approach 1:
The patent inverts the conventional approach to ESD clamp placement, moving from parallel to series configuration. This inversion eliminates the need for complex PCB tuning to compensate for impedance discontinuities, as the series configuration inherently maintains better impedance matching in high-speed interfaces.
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 approach enhances signal integrity by reducing impedance discontinuities, minimizing signal skew and reflections, and simplifying PCB design, while maintaining effective ESD protection and reducing costs and board space.
Implementation Method 1
series parasitic resistance and inductance of the DUT work against drawing ESD current away from the DUP
Implementation Method 2
series parasitic resistance and inductance of the DUT work against drawing ESD current away from the DUP
Implementation Method 3
the parallel parasitic capacitance creates an impedance discontinuity in the frequency band of interest
Data Source
AI summary
The embodiments of the apparatus and method described herein provide an integrated ESD/EOS protection solution which simplifies system PCB design for signal integrity compliance. As part of providing this solution, it is also desired to implement improved ESD/EOS protection and improved PCB routing.