Compaq BL10e Electrical signal integrity considerations for HP BladeSystem
Compaq BL10e - HP ProLiant - 512 MB RAM Manual
UPC - 613326445501
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Compaq BL10e manual content summary:
- Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 1
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 - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 2
available. The BladeSystem c-Class enclosures (c3000, c7000) are architected to ensure that they can support upcoming technologies and increasing demand -speed interfaces of the HP BladeSystem. This applies to all HP BladeSystem switch modules, mezzanine cards, server blades, and midplanes that use - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - 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 - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 4
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 - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - 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 5 - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 6
introduced by factors such as dielectric loss and the skin effect. Additionally, the reflections produced at impedance discontinuities, specifically at connector interfaces, become significant because they generate noticeable signal distortion. At these speeds, crosstalk between transmission lines - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 7
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 - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 8
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 - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 9
high-speed signal midplane that provides the flexibility to intermingle server blades and interconnect fabrics in many ways to solve a serializer/deserializer interface. The BladeSystem c-Class enclosure was designed and built to ensure that it can support upcoming technologies and their demand for - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 10
c-Class architecture must support dozens of server blades, more than 50 Mezzanine Cards (MEZZ) and I/O modules, and multiple enclosure designs. Target fabrics The HP BladeSystem provides high-speed interfaces between server blades and switch modules. Server blades may contain components connected - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 11
was important to ensure high-speed connectivity among all server blades and interconnect modules. To aid in the design of the signal midplane, HP involved the same signal integrity experts that design the HP Superdome computers. Specifically, HP paid special attention to several best practices - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 12
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 - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 13
to a trace, see Figure 12. Test pads should not be used. Figure 12. Remove non-functional pads Using data from a fiber weave investigation HP determined that the differences found among PCB fiber weaves were large enough at 10Gb/s to affect signal integrity. For designs that expect to operate at - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - 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 - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 15
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 divisions involved. HP has substantially - Compaq BL10e | Electrical signal integrity considerations for HP BladeSystem - Page 16
www.hp.com/servers/technology www.hp.com/go/bladesystem Call to action Send comments about this paper to [email protected]. © 2009 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The only warranties for HP products and services are
Electrical signal integrity considerations for
HP BladeSystem
technology brief
Introduction
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2
What is signal integrity
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2
Challenges
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4
Significant factors affecting signal integrity
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6
Dielectric losses
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6
Skin effect
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6
Impedance discontinuities
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6
Stubs
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7
Crosstalk
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8
Design goals
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9
Target fabrics
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10
Infrastructure architecture
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10
Implementation
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11
Specification library
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12
Board trace lengths
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12
Board layout and materials
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12
Summary
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15
For more information
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16
Call to action
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16