Compaq BL10e - HP ProLiant - 512 MB RAM Specification
Electrical signal integrity considerations
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- Setup and installation manual (156 pages) ,
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Electrical signal integrity considerations for
HP BladeSystem
technology brief
Introduction......................................................................................................................................... 2
What is signal integrity ........................................................................................................................ 2
Challenges.......................................................................................................................................... 4
Significant factors affecting signal integrity ............................................................................................. 6
Dielectric losses ............................................................................................................................... 6
Skin effect ....................................................................................................................................... 6
Impedance discontinuities ................................................................................................................. 6
Stubs .............................................................................................................................................. 7
Crosstalk......................................................................................................................................... 8
Design goals ....................................................................................................................................... 9
Target fabrics ................................................................................................................................ 10
Infrastructure architecture ................................................................................................................ 10
Implementation .................................................................................................................................. 11
Specification library ....................................................................................................................... 12
Board trace lengths ........................................................................................................................ 12
Board layout and materials ............................................................................................................. 12
Summary .......................................................................................................................................... 15
For more information.......................................................................................................................... 16
Call to action .................................................................................................................................... 16
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Table of Contents
Related Manuals for Compaq BL10e - HP ProLiant - 512 MB RAM
Summary of Contents for Compaq BL10e - HP ProLiant - 512 MB RAM
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Page 1: Table Of Contents
Electrical signal integrity considerations for HP BladeSystem technology brief Introduction............................2 What is signal integrity ........................2 Challenges............................4 Significant factors affecting signal integrity ..................... 6 Dielectric losses ..........................6 Skin effect ............................6 Impedance discontinuities ......................... -
Page 2: Introduction
Introduction A requirement for any server architecture is that it continues to meet future customer needs by supporting a built in capability to provide sustained high performance as technology driven bandwidth enhancements become available. The BladeSystem c-Class enclosures (c3000, c7000) are architected to ensure that they can support upcoming technologies and increasing demand for bandwidth and power for at least 5 to 7 years. - Page 3 As signal speeds increase additional effects inherent in the transmission media environment emerge as inhibitors to successful signal delivery. These effects include: • the physical characteristics of the material used for transmission, including materials adjoining the transmission media • the interference caused by the interaction of multiple simultaneous signals •...
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Page 4: Challenges
Challenges The NonStop signal midplane in a BladeSystem enclosure is capable of conducting extremely high signal rates of up to 10 Gb/s. Each half-height server blade has the cross-sectional bandwidth to conduct up to 160 Gb/s per direction. In a c7000 enclosure fully configured with 16 half-height server blades, the aggregate bandwidth is up to 5 Terabits/sec across the NonStop signal midplane. - Page 5 Figure 4. Measured eye diagrams from a 40" PCI-Compliance ISI trace Increasing frequency significantly increases attenuation. Skin resistive loss and dielectric loss are the primary components of frequency-dependent attenuation, as shown in Figure 5. Figure 5. Frequency dependent attenuation...
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Page 6: Significant Factors Affecting Signal Integrity
Significant factors affecting signal integrity A transmitted signal arriving at the receiver must maintain sufficient magnitude and quality to be reliably recognized. As signal frequency increases, previously inconsequential factors emerge as new obstacles. Line bandwidth is affected by attenuation introduced by factors such as dielectric loss and the skin effect. -
Page 7: Stubs
Stubs In PCB design, through-hole vias connect the signal path from one layer to another. As shown in Figure 6, many instances of this path leave a portion of the via unused. As signal speed increases, this unused portion of the via becomes a transmission line that can create significant reflections that can seriously reduce signal quality. -
Page 8: Crosstalk
Crosstalk As current moves through a conductor it creates an electromagnetic field. When two (or more) conductors run parallel to each other, the inductive and capacitive coupling between the paths can lead to interference. This interference is also known as crosstalk. Essentially, crosstalk is the coupling of a signal from one conductor into another adjacent conductor and is exacerbated by increasing transmitted signal speed and reducing the distance between adjacent conductors. -
Page 9: Design Goals
Design goals The BladeSystem c-Class uses a high-speed signal midplane that provides the flexibility to intermingle server blades and interconnect fabrics in many ways to solve a multitude of application needs. The NonStop signal midplane is unique because it can use the same physical traces to transmit GbE, Fibre Channel, 10 GbE, InfiniBand, Serial Attached Technology (SAS), or PCI Express signals. -
Page 10: Target Fabrics
Figure 9. Fabric technology targets Additionally, the design had to incur minimal additional cost for infrastructure to support fabrics yet to be developed, leverage industry standard components, and interoperate with the dozens of companies and multiple divisions involved. Over its lifecycle, the BladeSystem c-Class architecture must support dozens of server blades, more than 50 Mezzanine Cards (MEZZ) and I/O modules, and multiple enclosure designs. -
Page 11: Implementation
For double-wide switch modules, the main high-speed interface consists of two groups (eight pairs) of signals that are available from each server blade. These are used to route signals that require up to four Lanes, such as 10 GB Ethernet using the 3.125 Gbaud SERDES type of interface. -
Page 12: Specification Library
Specification library All server blade and midplane channels (and segments of channels) are required to meet the electrical specifications developed by HP, allowing separate vendors to create interoperable parts of the channel. The server blade vendor must ensure that any channel terminating at an IC on the server blade meets the same requirements as the combined effects of the server blade-to-MEZZ and MEZZ channel segments. - Page 13 The impedance of channels that include components and component pads should be adjusted by removing some of the adjacent ground plane under these components and pads. To prevent crosstalk and impedance discontinuities in other signals, no signals are routed under these “cutaways” in the ground layer.
- Page 14 of a board for more than two inches of cumulative distance. The length of trace segments that are parallel to the edge of a board should be minimized as much as possible. Traces should be at an angle of at least 10º to a board edge. This is to reduce the effects of PCB fiber weave on board impedance and propagation velocity on differential traces (see Figure 13).
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Page 15: Summary
Summary The BladeSystem c-Class enclosure was designed to ensure that it could support new high-speed technologies and their demand for both bandwidth and power for at least 5 to 7 years. Signal integrity issues arise as transmission frequencies increase. These issues require specific engineering to ensure that electronic circuits communicate reliably in the presence of signal impairments. -
Page 16: For More Information
For more information For additional information, refer to the resources listed below. Resource description Web address Industry Standard Server Technology www.hp.com/servers/technology Communications HP BladeSystem www.hp.com/go/bladesystem Call to action Send comments about this paper to TechCom@HP.com. © 2009 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.