EMC PCB simulation - Page 1
Forum section: electronics / general

author: mattko
author_rank: Contributor
timestamp: October 29, 2018, 10:08:47 am
content: Hello!I would like your input about simulating a PCB for EMC. The applications I'm most interested in is power electronics, so DC-DC and similar (with some communication). It should include conducted and radiated emissions.I have a few questions:-Which software is on the market (price does not matter)? (I found 3DS SIMULIA and Ansys Siwave).-Do these kind of programs support importing Altium PCB file?-How accurate are these kind of simulations and are they useful? I would like to hear your experience.-How long does it take to prepare and run a simulation like this to get useful results?I did not find a lot of info online about this topic, so I would be very happy to hear your experienceThanks!

author: Berni
author_rank: Super Contributor
timestamp: October 29, 2018, 10:16:55 am
content: Usually this sort of software is used for simulating RF circuits and antennas where the PCB itself is used as capacitors, inductors and delay lines.But i would like to hear if anyone is using it for things like switchmode converters.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 29, 2018, 06:56:00 pm
content: Heard of a couple things, ANSYS comes to mind. If you can't budget five digits... just do it the old fashioned way.It is possible to design a layout in such a way that it's relatively easy to analyze, and this can be hand-waved into a ballpark EMC assessment as well. I can do this, but it's much too involved to describe here unfortunately.Tim

author: mattko
author_rank: Contributor
timestamp: October 30, 2018, 01:52:23 pm
content: Quote from: T3sl4co1l on October 29, 2018, 06:56:00 pmWould u mind share some resources where this is described?I saw that u can do some conducted EMC even in LT Spice if u know what u are doing

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 30, 2018, 03:36:06 pm
content: Not that I know of; my approach is synthesized from physics principles, not from any particular source.There's always Henry W. Ott,Electromagnetic Compatibility Engineering, I forget if he goes into much detail as far as design-for-EMC-analysis, but many of the principles apply in general as part of signal quality and EMC control in the first place.Principles like using reference planes, so that -- in my case -- a trace can always be analyzed as a transmission line over that reference plane, and its in-circuit equivalent is fairly obvious, and its consequences as far as EMC should be fairly straightforward.Comparing between a well-grounded board and something a beginner would route (traces going every which way, and no ground pour, or a poorly connected pour), the intent is to reduce trace-to-trace coupling, so that instead of a random network of all fairly significant coupling factors (between pairs of traces), traces are reasonably well shielded from each other so they can be analyzed on a one-by-one basis. Consider all the couplings between all traces on a PCB, as the coupling matrix: in a naive layout, a lot of terms will have significant magnitudes; in a well-grounded layout, the matrix will be nearly sparse (i.e., most of the terms have magnitudes small enough to ignore).The less heavy-weight things to work with, as far as conducted emissions goes, is to consider the supernodes in the system. Don't look at, e.g., the mains input as line and neutral; look at line and neutral together, with respect to ground. Effectively, the common-mode analysis shorts H+N together -- justified by the large value X1 capacitor bridging them at RF. Do the same for internal nodes, and any groups leaving the board (e.g., DC+/-, output +/-, cables..). Note any unbalanced sources (e.g., switching transistor tab screwed to heatsink: a capacitor from switch node (lots of RF voltage) to ground; similarly between windings in the transformer, for isolated SMPS), and reduce the circuit to its common mode equivalent. Now you have a topology with known (approximately) noise voltages and branch impedances, and you have something to build a filter around.So, yeah, I'm dancing around E&M fields, network theory, linear algebra, circuit analysis theory and more here. It's... not easy to explain in a post.Tim

author: ddavidebor
author_rank: Super Contributor
timestamp: November 03, 2018, 02:22:14 pm
content: Quote from: mattko on October 29, 2018, 10:08:47 amThey often support importing ODB++ which altium can export

author: johnharold
author_rank: Newbie
timestamp: February 24, 2019, 03:50:50 am
content: I’m pretty sure ODB is dead.https://en.wikipedia.org/wiki/Ol%27_Dirty_Bastard

author: srce
author_rank: Regular Contributor
timestamp: March 05, 2019, 09:58:32 am
content: HyperLynx -https://www.mentor.com/pcb/hyperlynx/full-wave-solver/Sigrity -https://www.cadence.com/content/cadence-www/global/en_US/home/tools/ic-package-design-and-analysis/si-pi-analysis-point-tools/sigrity-powersi-3d-em-extraction-option.htmlADS/EMPro -https://www.keysight.com/en/pc-1297143/empro-3d-em-simulation-software?cc=US&lc=eng