Printed Circuit Design & Fab - April 2008 - (Page 21)

amplitude of high-speed signals and cause ISI5,10. Hence, when designing or testing a high-speed channel, it is crucial to consider the loss specifications. For instance, the loss budget for PCI Express Gen1 is specified as 13.2 dB at a frequency of 1.25 GHz. For SAS, the magnitude of insertion loss (SDD21) is given by a set of equations that can be analyzed using Mathcad as shown by FIGURE 4. Above examples demonstrate that Mathcad offers powerful capabilities for analyzing and solving signal integrity problems. Additional mathematical SI applications will be explored in Part 2 of this article. PCD&F DR. ABE (ABBAS) RIAZI is a senior staff electronic design scientist with Broadcom Corp. in Irvine, CA and can be reached at ariazi@broadcom.com. SAS channel insertion loss (within frequency range of 50 MHz to 5.0 GHz): f in Hz f := 50.00 • 106, 51.00 • 106 5 • 109 SDD21(f) := -10.884 if f > 3 • 109 -20 • log (2.71828) • [(6.5 • 10-6 • f 0.5) + (2 • 10-10 • f) + (3.3 • 10-20 • f2)] otherwise SDD21(f) (dB) 1 • 109 2 • 109 3 • 109 f (Hz) 4 • 109 5 • 109 FIGURE 4. Calculation of SDD21 magnitude in dB for SAS (3.0 Gb/s). REFERENCES 1. Howard Johnson and Martin Graham, “High-Speed Digital Design: A Handbook of Black Magic” Prentice Hall, 1993, PP 258-260, PP , . . 409-439. 2. Douglas Brooks, “Signal Integrity Issues and Printed Circuit Board Design” Prentice Hall, 2003, PP 18-21. , . 3. David Norte, “ Learn Signal Integrity Design Principles With Mathcad” , The EMC, Signal and Power Integrity Institute, 2005, PP 5-29, PP . . 41-48. 4. Howard Johnson and Martin Graham, “ High-Speed Signal Propagation: Advanced Black Magic” Prentice Hall, 2003, PP 249-250. , . 5. Eric Bogatin, “Signal-Integrity Simplified” Prentice Hall, 2004, P 257. 262, PP 334-335. . 6. Stephen H. Hall, Garrett W. Hall, James A. McCall, “High-Speed Digital System Design A Handbook of Interconnect Theory and Design Practices” John Wiley & Sons Inc., 2000, PP 102-104. , . 7. Istvan Novak and Jason R. Miller, “ Frequency Domain Characterization of Power Distribution Networks” Artech House Inc., 2007, PP , . 43-54. 8. “Mathcad 2001 User’s Guide” Math Soft Inc. 2001, P 286 , . 9. “Information technology – Serial Attached SCSI – 1.1 (SAS-1.1)” Work, ing Draft American National Standard, Project T10/1601-D, Revision 10, September 21, 2005, PP 136-146. . 10. Abe Riazi, “Timing Analysis Techniques for Digital PCBs, Printed ” Circuit Design & Fab, February 2008, PP 17-19. . B P O SE EX RIN OT E U PO TE H 1 S 3A LA D C 26 T S IR IP VE CU C G IT AS IMAGECURE SMART® A UNIQUE ADVANCED RESIN TECHNOLOGY Utilising a unique advanced resin technology developed by Sun Chemical, we are now able to offer a new SMART (SolderMask Advanced Resin Technology) product, which meets the industry needs of tomorrow, today. ImagecureSMART ® OFFERS: Halogen free Meets all current OEM specifications Lower temperature pre-dry window offering a significantly harder tack-free finish One product with increased photospeed allowing exposure by LDI or standard contact printingsystems One product for both Solvent and Aqueous developing Ability to hold fine lines and features Excellent resistance to all current final surface finishes including lead free solder Can be laser ablated for ease of traceability RoHs compliant Sun Chemical Circuits Norton Hill Midsomer Norton Bath BA3 4RT United Kingdom Tel: +44 (0) 1761 414 471 Fax: +44 (0) 1761 416 609 www.sunchemicalcircuits.com APRIL 2008 PRINTED CIRCUIT DESIGN & FAB 21 http://www.sunchemicalcircuits.com http://www.sunchemicalcircuits.com

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Printed Circuit Design & Fab - April 2008 Contents Our Line Market Watch Around the World Happenings ROI Tip Jar Interconnect Strategies Positive Plating Improving Fabrication Yields by Design Solve Design Problems with Signal Integrity Optimization Laser Direct Imaging Made Easy Troubleshooting the Innerlayer Process SIPS Give More to Moore Off the Shelf Marketplace Ad Index BGA Bulletin

Printed Circuit Design & Fab - April 2008

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