Design of High-Speed Circuits 🚧

Factors to Consider in High-Speed PCB Design

Cost control
Layer stack-up principles
Layout principles
Routing principles
Impedance design
Signal integrity
Power integrity
EMC design
Thermal design
DFM design

Differences Between Two-Layer and Multilayer Boards

Calculation of reference planes and impedance
Shorter return paths in multilayer boards
Easier routing
Higher cost of multilayer boards

Layer Stack-up Guidelines

Components and soldering surfaces should have complete ground planes (for shielding purposes)
Avoid adjacent parallel routing layers as much as possible (to prevent interference)
All signal layers should be adjacent to ground planes; critical signals should be adjacent to ground layers without crossing split planes (to minimize return paths)

Based on the above, the recommended layer stack-up scheme is:

Top layer: Signal 1
Inner layer 1: Ground
Inner layer 2: Power
Bottom layer: Signal 2

To reduce edge radiation, the power layer should be pulled back at least 1 mm from the ground layer.

PCB Impedance Design Requirements for Different Communication Protocols

High-Speed Signal	Impedance Requirement	Tolerance	Routing
DDR	100Ω	±10%
eMMC	50Ω	±10%
PCIe
USB	90Ω	±10%	Differential
HDMI	100Ω	±10%
eDP	90Ω	±10%	Differential
MIPI	100Ω	±10%	Differential
SDIO/SDMMC	50Ω	±10%

Some Basic Concepts

Signal Integrity: Signal integrity refers to the quality of a signal on a signal line. Good signal integrity means that the signal has the necessary voltage levels when needed.
Transmission Line: A transmission line is a connection line composed of two conductors

References and Acknowledgements

Original: https://wiki-power.com/ This post is protected by CC BY-NC-SA 4.0 agreement, should be reproduced with attribution.

This post is translated using ChatGPT, please feedback if any omissions.