yu.yanfeng

Use HL 8.0 PI to deal with EMI Issues In PCB?

Discussion created by yu.yanfeng on Mar 6, 2009
Latest reply on Mar 6, 2009 by yu.yanfeng

Today, Many of PCB designers wish to cover EMI Issues in pcb  to avoid costed-respins and decrease time to market, especially for those comsumer portable devices where no metal shielding case exits.

 

It's not easy to design one-pass PBA .Many designers think PI/SI tools can help them to take this challenge, and think the EMI source be in common-mode  noise, so they have put much effort to find what happened in the planes. Sigrity PowerSI and Ansoft SIwave are mostly-used tools. Did they get successful?  I think not. The darkness of tools be there(Eric have told us). Does Hyperlynx PI can make this dream come to true by it's easy to use and easy to understand? Let's see how they think about the EMI issue( Of course, I never dream the EMI issues can be covered by simple simulation without  chip's CPM models which is not available to system designer,aslo not feasible to measure ).

 

Here I posted the story to introduce what they think about EMI in PBA:

 

In a PCB, PWR and GND planes are used to carry charge to a chip. When a chip draws current, some charge is moved from power to ground for its operation. Assume there is no PCB lumped capacitors and the charge has to be brought from its distributed storage between two planes. The charge initially moves in one direction on the power plane and creates a voltage gradient on the power plane and a similar and opposite effect has to exist on the ground plane. After the demand of charge displacement stops, the redistribution of voltage gradient and new charge distribution has to return back to its equipotential equilibrium. How long this return back to steady state takes will depend on the natural response of the power and ground plane system.
1.GIF

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