Zhang / Krooswyk / Ou High Speed Digital Design

Design of High Speed Interconnects and Signaling
1. Auflage 2015
ISBN: 978-0-12-418667-5
Verlag: Academic Press
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 272 Seiten, Format (B × H): 191 mm x 235 mm

High Speed Digital Design discusses the major factors to consider in designing a high speed digital system and how design concepts affect the functionality of the system as a whole. It will help you understand why signals act so differently on a high speed digital system, identify the various problems that may occur in the design, and research solutions to minimize their impact and address their root causes. The authors offer a strong foundation that will help you get high speed digital system designs right the first time. Taking a systems design approach, High Speed Digital Design offers a progression from fundamental to advanced concepts, starting with transmission line theory, covering core concepts as well as recent developments. It then covers the challenges of signal and power integrity, offers guidelines for channel modeling, and optimizing link circuits. Tying together concepts presented throughout the book, the authors present Intel processors and chipsets as real-world design examples. - Provides knowledge and guidance in the design of high speed digital circuits - Explores the latest developments in system design - Covers everything that encompasses a successful printed circuit board (PCB) product - Offers insight from Intel insiders about real-world high speed digital design

Hanqiao Zhang is an Analog Engineer at Intel and holds a PhD degree in Electromagnetics and Microwave Engineering from Clemson University. Hanqiao joined Intel Xeon product electrical validation team in 2011, where he worked on generations of Intel high-speed digital systems. He developed methodologies for validating high-speed interfaces, such as PCI Express and Quick Path Interface (QPI). Hanqiao is now a signal integrity engineer with Intel Data Center Group. He is involved in mission-critical high-performance servers signal integrity design, bring up, validation and debug.

Zielgruppe

<p>Computer engineers, system designers, and students in these disciplines seeking knowledge and guidance in the design of high speed signaling and interconnects.</p>

Autoren/Hrsg.

Zhang, Hanqiao

Krooswyk, Steven

Ou, Jeffrey

Fachgebiete

• Technische Wissenschaften Elektronik | Nachrichtentechnik Elektronik Schaltungsentwurf

Inhaltsverzeichnis

- Transmission Line Fundamentals
- PCB Design for Signal Integrity
- Channel Modeling and Simulation
- Link Circuits and Architecture
- Measurement and Data Acquisition Techniques
- Designing and Validating with Intel Processors

Leseproben

Chapter 1

Transmission line fundamentals

The chapter introduces the electromagnetics and presents the origin physics of the Maxwell’s equations. Electromagnetic wave propagation equations in both free space and conductive media are derived. Transmission line theory laying the foundation for signal integrity analysis and interconnect design is discussed. Commonly used transmission lines in today’s high-speed systems and new development trends for them are presented in the last section of the chapter.

Keywords

Maxwell’s equations; transmission line theory; plane wave; electromagnetics

All the mathematical sciences are founded on relations between physical laws and laws of numbers, so that the aim of exact science is to reduce the problems of nature to the determination of quantities by operations with numbers.

— James Clerk Maxwell

The chapter introduces electromagnetics and presents the origin physics of Maxwell’s equations. Electromagnetic wave propagation equations in both free space and conductive media are derived. Transmission line theory laying the foundation for signal integrity analysis and interconnect design is discussed. Commonly used transmission lines in today’s high-speed systems and new development trends for them are presented in the last section of the chapter.

Basic Electromagnetics

Starting with the introduction of integral and derivative forms of Maxwell’s equations, four physical laws composing Maxwell’s equations are explained. Four fundamental electromagnetic field vectors, building blocks of electromagnetics, are also presented. Lastly the propagation of electromagnetic waves is covered.

Electromagnetics Field Theory

Maxwell’s equations

By introducing the concept of displacement current, Maxwell’s summarized the famous equation set describing the electromagnetic phenomenon that electric field can induce magnetic field and vice versa. By combining the equations representing four electromagnetic physics laws, the integral form of Maxwell’s equations are written as below:

?1H·dl=?s(Jc+?D?t)·dS?1E·dl=-?s?B?t·dS?SD·dS=?v?dv?SB·dS=0 (1.1)

(1.1)

Symbols used are defined as follows: electric field intensity (V/m), electric flux density (C/m2), magnetic field intensity (A/m), and magnetic flux intensity (T). is the conducting current density (A/m2), s is the media conductivity (S/m). and and and are dependent. Relationships between and , and , and and in isotropic media are:

=eE,B=µH,andJc=sE (1.2)

(1.2)

Electric field intensity is defined as the electric force experienced by a unit positive charge in an electric field:

=Fq (1.3)

(1.3)

Symbol in the equation is the quantity of charge on the test charge experiencing the force. is the force experienced by the test charge.

Electric flux density is used to define the electric field in dielectric materials where the dielectric can be polarized by an applied electric field. The induced dielectric polarization density is defined as :

=e0E+P (1.4)

(1.4)

where 0 is the electric permittivity of free space, 0=8.85×10-12F/m.

In a linear and isotropic media, is defined as:

=?ee0E (1.5)

(1.5)

where e is the electric susceptibility of the dielectric material. It is a measure of how easily it polarizes in response to an electric field. The electric flux density is further written by:

=e0erE=eE (1.6)

(1.6)

where =e0(1+?e), the electric permittivity of the dielectric material, and r=1+?e is the relative permittivity of the dielectric.

Magnetic field strength or magnetic flux density is a vector used to describe magnetic field. It relates the magnetic force experienced by a particle carrying a charge of coulomb to the magnetic field the charge is passing through at a speed of ,

=qv×B (1.7)

(1.7)

As dielectric being polarized by an applied electric field, magnetic media can be magnetized by an applied magnetic field. The magnetization is defined as . In a linear and isotropic media, is defined as:

=?mH (1.8)

(1.8)

where m is the magnetic susceptibility.

The magnetic flux density can be written as:

=µ0H+µ0M (1.9)

(1.9)

where 0 is the permeability of free space, 0=4p×10-7H/m. And,

=µ0µrH=µH (1.10)

(1.10)

where =µ0(1+?m) is the permeability of the magnetic media. r=1+?m is the relative permeability of the media.

Magnetic field is given by:

=Bµ0-M (1.11)

(1.11)

Maxwell’s equations formulate the interactions of vector fields , , , and . They are the cornerstones for the study of electromagnetic field and electromagnetic waves. The integral form of Maxwell’s equation describes the relationship between different vector fields in certain regions—for example, a symmetric distribution of charges and currents. However, in practical applications less symmetric situations and/or vector fields at a certain location in the region are usually desired. In these cases the differential form of Maxwell’s equations are more often used. The differential forms of Maxwell’s equations are summarized below:

?×H=Jc+?D?t?×E=-?B?t?·D=??·B=0 (1.12)

(1.12)

Each equation of Maxwell’s equations represents a physics law observed in experiments. Their details are discussed in following sections.

Ampere’s law

Starting with Ampere’s law with displacement current correction, the origin of Ampere’s law states that magnetic fields can be generated by electrical current:

lH·dl=I (1.13)

(1.13)

The equation shows that the circulation or the line integral of the magnetic field is equal to the sum of the current inside the curl. However, this form of Ampere’s law does not apply to a non-continuous conducting current. Consider the situation in Figure 1.1: when a capacitor is being charged there will be a continuous conducting current outside of the capacitor. However, inside the capacitor there will be no conducting current. The magnetic circulation has different values depending on which surface surrounded is selected. When the current inside the surface S1 is , and in contrast the current inside the surface S2 is 0, both the surfaces are bounded by path . Maxwell’s correction by introducing displacement current filled this gap in the original Ampere’s law. The correction shows that not only does a continuous conducting current induce a magnetic field, but also a changing electric field induces a magnetic field. Ampere’s law can be rewritten as:

lH·dl=Ic+Id

where Ic is the conducting current and Id is the displacement current.

Figure 1.1 Current going through different surfaces around a capacitor being charged.

Since,

=?sJ·dS

1H·dl=?s(Jc+Jd)·dS=?s(Jc+?D?t)·dS (1.14)

(1.14)

where and are conducting current density and displacement current density, respectively.

Faraday’s law

Faraday’s law summarizes that a voltage or electromotive force (EMF) can be produced by the altering magnetic flux in an electric circuit. The induced EMF () is equal to the negative change rate of magnetic flux B:

=-dFBdt (1.15)

(1.15)

where is EMF. B is the magnetic flux (Wb). FB is defined as:

B=?sB·dS (1.16)

(1.16)

...

Über Autor(innen)

Ou, Jeffrey
Jeffrey Ou joined Intel in 1999 as an analog design engineer in CMOS RF transceiver design. In 2006, Jeffrey transitioned to Xeon processor product design team in Server Development Group (SDG) developing a serial I/O module configurable for PCI Express and Quick Path Interface (QPI). Since then Jeffrey has been involved in several generations of Xeon products from design to post silicon validation. In 2012, Jeffrey was recognized as a tech lead in SDG, and continued to develop the cutting-edge high speed serial I/O modules for server products. Jeffrey holds a PhD degree in EECS from UC Berkeley and is a member of IEEE.

Zhang, Hanqiao
Hanqiao Zhang is an Analog Engineer at Intel and holds a PhD degree in Electromagnetics and Microwave Engineering from Clemson University. Hanqiao joined Intel Xeon product electrical validation team in 2011, where he worked on generations of Intel high-speed digital systems. He developed methodologies for validating high-speed interfaces, such as PCI Express and Quick Path Interface (QPI). Hanqiao is now a signal integrity engineer with Intel Data Center Group. He is involved in mission-critical high-performance servers signal integrity design, bring up, validation and debug.

Krooswyk, Steven
Steve Krooswyk has been at Intel since 2003 when we joined as a signal integrity engineer for EPSD server development. In 2009, Steve transitioned into the signal integrity lead for PCI Express in Intel's Enterprise Platform Technology Division (EPTD). In addition to server products, his experience includes involvement in the PCI Express 3.0 and 4.0 specifications. He holds a B.S. and M.S. in electrical engineering from the University of South Carolina.