<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>High-speed and high-frequency PCB interconnect solutions with the slightest discontinuities in the physical geometry along the microstrip transmission line can significantly degrade the integrity of the signal being transferred. This paper presents an analysis of SMT component pads and their impact on the successive transmission line impedance. During 0805, 1206 and 2512 package size SMT component pad discontinuity evaluations it was spotted, that the increasing deviation from target impedance affects the microstrip impedance segment following the discontinuity. A 25 Ω impedance offset at the SMT pad reduces the line impedance afterwards by up to 7 Ω. A 37 Ω impedance offset results in a microstrip impedance reduction by up to 15 Ω<italic>,</italic> whereas a 45 Ω impedance change leads to a reduction of successive segment impedance by up to 30 Ω. This effect is also present in multiple evenly-spaced discontinuities. But a single reference plane cut-out, which is twice as wide as the SMT component discontinuity, substantially improves the overall impedance of the transmission line, including the successive line segment impedance drop.</p>
</abstract>

High-speed and high-frequency PCB interconnect solutions with the slightest discontinuities in the physical geometry along the microstrip transmission line can significantly degrade the integrity of the signal being transferred. This paper presents an analysis of SMT component pads and their impact on the successive transmission line impedance. During 0805, 1206 and 2512 package size SMT component pad discontinuity evaluations it was spotted, that the increasing deviation from target impedance affects the microstrip impedance segment following the discontinuity. A 25 Ω impedance offset at the SMT pad reduces the line impedance afterwards by up to 7 Ω. A 37 Ω impedance offset results in a microstrip impedance reduction by up to 15 Ω, whereas a 45 Ω impedance change leads to a reduction of successive segment impedance by up to 30 Ω. This effect is also present in multiple evenly-spaced discontinuities. But a single reference plane cut-out, which is twice as wide as the SMT component discontinuity, substantially improves the overall impedance of the transmission line, including the successive line segment impedance drop.

Analysis of SMT component land pad discontinuity effect on the overall transmission line impedance in high-speed applications

Department of Computer Science and Communications Technologies

Journal of Electrical Engineering

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

High-speed and high-frequency PCB interconnect solutions with the slightest discontinuities in the physical geometry along the microstrip transmission line can...

Analysis of SMT component land pad discontinuity effect on the overall transmission line impedance in high-speed applications

Publicado en línea: 08 may 2023

Páginas: 122 - 126

Recibido: 16 mar 2023

DOI: https://doi.org/10.2478/jee-2023-0016

Palabras clave
SMT discontinuity, land pad discontinuity, impedance compensation, cut-out

© 2023 Vaidotas Barzdenas et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Analysis of SMT component land pad discontinuity effect on the overall transmission line impedance in high-speed applications

Publicado en línea: 08 may 2023

Páginas: 122 - 126

Recibido: 16 mar 2023

DOI: https://doi.org/10.2478/jee-2023-0016

Palabras claveSMT discontinuity, land pad discontinuity, impedance compensation, cut-out

© 2023 Vaidotas Barzdenas et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Palabras clave
SMT discontinuity, land pad discontinuity, impedance compensation, cut-out