IEEE Circuits and Systems Magazine - Q3 2020 - 34

Feature

High-Speed
Printed Circuit
Boards:
A Tutorial
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Mohammad Abu Khater, Senior Member, IEEE

Abstract
Circuit designers often tend to overlook Printed Circuit Board
(PCB) designs. Circuits performance and the quality of measurements, however, are strongly correlated with careful and
comprehensive PCB design techniques. Such design techniques are applicable to practically all circuits areas including
analog, digital, RF, and power applications. This paper provides
a fundamental understanding of common problems faced in
designing high-performance and high-speed PCBs. While this
tutorial paper does not cover basics of PCBs, it presents empirical and commonly practiced methods to deliver professional
layouts. This includes studying on-board transmission lines and
their matching techniques, various PCB structures that ensure
good signal integrity, and bypass capacitors, for circuits up to
30 GHz. Conclusions and suggestions are justified with theoretical analysis and supported by simulations and measurements.

I. Introduction
early all hardware designs involve a PCB. A poorly designed PCB, however, can result in adverse
reflections, couplings, ground bouncing, and other
problems which can render the circuit unstable or with
inferior performance. With very little room for error, it is
essential for a circuit designer to be aware of signal integrity issues, and how to avoid them.
The increasing density and speed of electronics
-today only exacerbates the issues encountered in a

Digital Object Identifier 10.1109/MCAS.2020.3005484
Date of current version: 12 August 2020

IEEE CIRCUITS AND SYSTEMS MAGAZINE

PCB design. As a result, continuous efforts exist to improve design techniques. For example, in [1]-[3], Electromagnetic interference (EMI) modeling and reduction
techniques are investigated. In addition, various crosstalk handling techniques are discussed in [1], [4]-[6]. In
[7], a detailed survey is presented for PCB link model,
differential signaling, non-ideal return paths, and modeling of manufacturing tolerances. A shorter review on
PCB characteristics is presented in [8].
The purpose of this paper is to provide a practical
and concise, yet fundamental, understanding of PCB signal integrity, and a guideline to avoid common mistakes.
For high-speed operation, PCB traces are studied using
the available RF transmission line (TL) theory. Various
PCB TL structures are investigated for frequencies up to
10-30 GHz. The conclusions are supported with simulations and measurements.
The paper is organized as follows: Section II discusses a brief background including the history of PCBs, a
generic design flow, and how to diagnose a faulty PCB.
Section III provides analysis for on-board TLs, and proper matching (or termination) techniques. Various traces
and PCB structures are discussed in Section IV, along
with their corresponding signal integrity performance.
In Section V bypass capacitors are examined. Skin effect
and vias are discussed briefly in Section VI. Lastly, the
paper is concluded in Section VII.

THIRD QUARTER 2020

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IEEE Circuits and Systems Magazine - Q3 2020

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