Crosstalk in Transmission Lines

Posted on Edited on In

Electromagnetic coupling

Electric field coupling (also called capacitive coupling) occurs when energy is coupled from one circuit to another through an electric field

Two circuits above a signal return plane.

Magnetic field coupling (also called inductive coupling) occurs when energy is coupled from one circuit to another through a magnetic field

Two circuits above a signal return plane

For instance

  • magnetic coupling between multiple inductors
  • capacitive coupling between multiple transmission lines

Return Path

image-20250705171613361

Current return paths are frequency dependent \(Z = R +j\omega L\)

  • Low frequency
    • \(R\) dominates - current use as many returns as possible to have parallel resistances
  • High frequency
    • \(j\omega L\)​ dominates - current use the closest possible return path to form the smallest possible loop inductance
  • Very high frequency
    • The current would be confined to the nearest possible return only at ultra-high frequencies (skin effect)

image-20250705170949035

skin effect & Dielectric loss

image-20250705170028485

EMX simulation

setup:

image-20250706004037966

frequency sweep:

image-20250706010943996

Cadence October 2020, Analysis of a Figure-Eight Inductor with EMX RAK

image-20250706010216105

Tline Approximation

[https://web.stanford.edu/class/archive/ee/ee371/ee371.1066/handouts/markChapt.pdf]

Eric Bogatin. Pop Quiz: When is an Interconnect Not a Transmission Line? [https://www.signalintegrityjournal.com/blogs/4-eric-bogatin-signal-integrity-journal-technical-editor/post/265-pop-quiz-when-is-an-interconnect-not-a-transmission-line]

image-20250817105056325

image-20250817105203031image-20250817105308602

image-20260115210350617

Decoupling Capacitor

image-20250705175343498

image-20260125205518872

image-20260125205941736

image-20260125211108504

Grounding

Chapter 11 Layout and grounding [http://ieb-srv1.upc.es/gieb/tecniques/doc/EMC/pdfs/ScienceDirect_articles_27Jul2018_12-16-10.699/Chapter-11---Layout-and-grounding_2007_EMC-for-Product-Designers.pdf]

TODO

reference

信号完整性揭秘:于博士SI设计手记

Bogatin, E. (2018). Signal and power integrity, simplified. Prentice Hall. [pdf]

High-speed Serial Interface Lect. 9 – Noise [http://tera.yonsei.ac.kr/class/2017_2_2/lecture/Lect%209%20Noise.pdf]

Yuriy Shlepnev. How Interconnects Work: Characteristic Impedance and Reflections [https://www.linkedin.com/pulse/how-interconnects-work-characteristic-impedance-yuriy-shlepnev/]

—. How Interconnects Work: Bandwidth for Modeling and Measurements [https://www.linkedin.com/pulse/how-interconnects-work-bandwidth-modeling-yuriy-shlepnev/?trackingId=874kpm3XuNyV9D0eP6IioA%3D%3D]

Eric Bogatin. Pop Quiz: When is an Interconnect Not a Transmission Line? [https://www.signalintegrityjournal.com/blogs/4-eric-bogatin-signal-integrity-journal-technical-editor/post/265-pop-quiz-when-is-an-interconnect-not-a-transmission-line]

TeledyneLeCroy/SignalIntegrity Python tools for signal integrity applications [SignalIntegrityApp]

A Look at Transmission-Line Losses [http://blog.teledynelecroy.com/2018/06/a-look-at-transmission-line-losses.html]

How Much Transmission-Line Loss is Too Much? [http://blog.teledynelecroy.com/2018/06/how-much-transmission-line-loss-is-too.html]

Raymond Y. Chen, Raymond Y. Chen. Fundamentals of S Fundamentals of S-Parameter Parameter Modeling for Power Distribution Modeling for Power Distribution System (PDS) and SSO Analysis System (PDS) and SSO Analysis [https://ibis.org/summits/jun05/chen.pdf]