Printed Circuit Design & Fab - December 2008 - (Page 37)

SySTEM dESiGn compare well between measurements and hybrid analysis. Given the engineering uncertainty of emissions, predictions are +/- 5 dB versus the typical expectations of +/- 5% for circuit design applications. This correspondence is quite adequate to assure EMC issues are well predicted by SI/PI/ EMC hybrid analysis prior to manufacturing physical prototypes. Design changes can be quickly prototyped and verified with one half hour of engineering time for setup, a few hours of computer time for the analysis and 15 minutes of interactive results post processing. Government compliance specifications still must be certified by measurement for end products, but system-level PCB emissions analysis can yield a faster time to market by requiring fewer design iterations and board turns, and it can significantly reduce risks of EMC challenges when PCBs are incorporated into larger systems. SI, PI and EMC are three sides of the same coin. It is important to recognize the relationship between SI and PI challenges, as mandated by required current loops and twoterminal voltages. In fact, SI and PI issues are indistinguishable. Similarly, SI and PI issues are the perpetrators of EMC challenges. System-level hybrid analysis is a vehicle by which these three inseparable challenges can be considered within PCB design flow. pCd&f Brad BriM has product marketing responsibilities for Sigrity in the area of IC package and PCB extraction and can be reached at bradb@sigrity.com FiGurE 6. Measured vs. modeled magnetic fields near a DDr memory block (courtesy lG electronics, Korea ). The DDR memory block of a complex PCB design is examined for emissions issues because it contains parallel buses and synchronous clocks – known to cause EMC issues. This design was characterized with system-level SI/PI hybrid analysis. The transient signals applied by the hybrid analysis were specified to correspond as closely as possible to the actual operating condition of the PCB, and cables were not considered in the hybrid analysis. Magnetic fields near the surface of the board were measured and compared to magnetic fields computed from SI/PI hybrid analysis results. The DDR board block is shown on the left portion in FiGurE 6 and the measured results are compared to the hybrid analysis results on the right. Color-shading scales are the same for the measurement. The spatial distribution amplitude of the magnetic fields Exhibition: February 11, 2009 Hilton Phoenix East/Mesa Mesa, AZ • 1-day tabletop exhibition • Free technical sessions • Reception on the show floor • Great networking opportunities • And much more! www.pcbshows.com/phoenix www.pcbshows.com/phoenix DECEMBER 2008 Brought to you by printEd CirCuit dESign & fAB 37 http://www.pcbshows.com/phoenix http://www.pcbshows.com/phoenix http://www.pcbshows.com/phoenix

Table of Contents Feed for the Digital Edition of Printed Circuit Design & Fab - December 2008

Printed Circuit Design & Fab - December 2008 Contents Our Line Market Watch Around the World Happenings ROI Global Sourcing EMC for the Real World Interconnect Strategies On the Forefront Final Finish Forum Test and Inspection Electronic System Design Data Management 101 Designers Take on Technology Challenges in 2008 PCB Signal Integrity, Power Integrity and EMC Challenges What’s in a Name? Ad Index PCB Dielectric Materials for High-Speed Applications Off the Shelf Marketplace BGA Bulletin

Printed Circuit Design & Fab - December 2008

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