OK, I guess SI-LIST removes links in signatures... Here's the link to the newspaper registration. Sorry for the high noise to signal, as someone mentioned. http://www.emc-seminars.com/Newsletter/Newsletter.html _______________________ Kenneth Wyatt Wyatt Technical Services LLC Woodland Park, CO Email Me! | Web Site | Blog Subscribe to Newsletter Connect with me on LinkedIn On Jan 7, 2012, at 6:14 PM, Ken Wyatt wrote: > Hmmm...just noticed the links were removed in my last post. Now you should be > able to click on the link "Subscribe to Newsletter" (below) to obtain the > list of troubleshooting tips and past newsletters. > Cheers, Ken > _______________________ > Kenneth Wyatt > Wyatt Technical Services LLC > Woodland Park, CO > Email Me! | Web Site | Blog > Subscribe to Newsletter > Connect with me on LinkedIn > > On Jan 7, 2012, at 5:23 PM, Ken Wyatt wrote: > >> Great reply Alfred - lots of good troubleshooting tips. >> >> Your comment on the PSA2701T caught my eye, as I've been using one of these >> for several years. However, few people have heard of the TTi Spectrum >> Analyzer, which is too bad. It's an incredible handheld (truly handheld!) >> instrument manufactured in the UK and distributed by Newark Electronics and >> Saelig Co. here in the US. Saelig actually has a slightly better price at >> $1,887. If anyone is interested in additional info on the TTi PSA2701T >> spectrum analyzer, I posted a comprehensive review on my web site: >> http://www.emc-seminars.com/Technical_Articles/files/TTi_PSA2701T_Spectrum_Analyzer_Wyatt.pdf. >> >> I'm also glad you referenced Doug Smith's web site. It's chock-full of >> high-frequency, EMC and ESD measurement techniques and tips. He's at: >> http://emcesd.com/ >> >> By the way, anyone who registers for my free quarterly EMC newsletter will >> receive a link to a free list of troubleshooting tips, as well as all past >> newsletters. Click on the link below... >> >> References: >> >> Newark: >> http://www.newark.com/aim-tti-instruments/psa2701t/analyzer-spectrum-1mhz-to-2700mhz/dp/54M5938 >> >> Saelig: http://www.saelig.com/category/TEEMCEE.htm >> >> Cheers, Ken >> _______________________ >> Kenneth Wyatt >> Wyatt Technical Services LLC >> Woodland Park, CO >> Email Me! | Web Site | Blog >> Subscribe to Newsletter >> Connect with me on LinkedIn >> >> On Jan 7, 2012, at 1:16 PM, alfred1520list wrote: >> >>> Guess one more post does not alter the SNR significantly:) >>> >>> Quarter wave of 513 MHz in free space is 5.76", and roughly >>> half that in FR4. I guess you don't happen to have a 3" tall >>> metal standoff that's mounted close to the ASIC to act as >>> an antenna, right? Any way, controlled impedance traces aren't >>> efficient antenna compare to other physically large structure. >>> As some one else pointed out, common mode current can >>> couple to other physically large structures and they become >>> efficient radiator. I find Doug has a few excellent papers >>> on EMI on his site: >>> >>> http://emcesd.com >>> >>> I find this particular interesting: >>> >>> "Current Probes, More Useful Than You Think": >>> http://emcesd.com/pdf/iprobe98.pdf >>> >>> One other suggestion from experience. When you have 20 suspects >>> areas, it might be easier trying to make it worst to see which one >>> of them is the dominant source. Even though all 20 suspects can all >>> radiate, probably only one of them is order of magnitude higher >>> than others. If you can find that one and knock it down, you made >>> significant progress. Since at 513 MHz it still needs significant physical >>> dimension (like an 1" long???) to radiate efficiently, use a piece of metal >>> like X-Acto knife, to touch everything and see if it make it worst. Any >>> where you touch and made it worst is worth a closer look, especially >>> places where you don't expect, e.g. power supply, etc. >>> >>> Speaking of sniffing radiation, I have used PSA2701T: >>> http://www.tti-test.com/products-tti/rf/spectrum-analyzer.htm >>> >>> It's a great piece of gear and low enough in cost (a couple of US dollar as >>> I recall). Since you aren't making certification measurement, you can >>> simply use any length of wire that register a reading at the frequency of >>> interest and make relative measurement. I used a cheap US$30 discone >>> antenna. If you make the spike smaller, you have made it better. >>> >>> >>> Best Regards, >>> Alfred Lee >>> >>> Web: www.mds.com >>> >>> ----- Original Message ----- >>> From: "Eric Steimle" <eric.steimle@xxxxxxxxxx> >>> To: "vinod ah" <ah.vinod@xxxxxxxxx>; "SI-LIST" <si-list@xxxxxxxxxxxxx> >>> Sent: Saturday, January 07, 2012 11:27 AM >>> Subject: [SI-LIST] Re: DDR3 clock failing radiation Tests >>> >>> >>>> I agree that seeing the most emissions coming out of the ASIC is pretty >>>> common, especially if it's your ASIC ;), and unless you >>>> have some kind of crazy expensive (possible magic) software, simulation >>>> can't save you now. I don't know what your application is >>>> but in the past I did a lot of unshielded consumer designs that used >>>> DDR2/3, and most of them would not have made it through scan >>>> without spread spectrum. I also agree that going to an expert EMI >>>> consultant could be well worth it, if your in NC I know a good >>>> one. >>>> Anyway I like to tackle emi problems by cutting everything into smaller >>>> and smaller pieces. I don't know what your production >>>> options are but here's one thing to try. If you want to narrow things >>>> down you could build yourself a shield for your ASIC as a >>>> test. Just get some Kapton tape, and some copper tape. Kapton tape all >>>> around the ASIC, then copper tape over that. Then ground >>>> the heck out of that copper tape, I usually do that by taking an exacto >>>> knife and cutting down to my gnd plane, but do what you >>>> can do. After that sniff it again, or go pre-scan it if you can afford it. >>>> >>>> If that does nothing, at least you know you have additional problems >>>> elsewhere. If it cleans it up, hurray just ship everything >>>> with copper tape. Kidding but you could re-spin the board to accommodate >>>> a shield, and get the product out the door. >>>> >>>> This is just one of hundreds of things to try, but you asked for help >>>> finding the source. The best advice I can give is to start >>>> eliminating things, by shielding / pulling parts off the board, changing >>>> clock frequencies, anything you can think of to narrow >>>> down the problem. Keep track of how each change affects your emissions. >>>> One time we ripped 12 ASICs off a large board and still >>>> had the problem! It was a lot easier to find without all those extra parts >>>> to question though. >>>> >>>> Good luck. >>>> >>>> >>>> Eric F. Steimle >>>> Hardware Engineering Manager >>>> >>>> +1 732-440-1280 x210 Office >>>> +1 732-212-9424 Fax >>>> >>>> 444 Route 35 South >>>> Building B >>>> Eatontown, NJ 07724 USA >>>> >>>> eric.steimle@xxxxxxxxxx >>>> www.altior.com >>>> >>>> >>>> >>>> ****Confidentiality Statement**** >>>> This message (including any attachments) contains confidential information >>>> intended for a specific individual and purpose, and is protected by law. If >>>> you are not the intended recipient, you should delete this message and are >>>> hereby notified that any disclosure, copying, or distribution of this >>>> message, >>>> or the taking of any action based on it, is strictly prohibited. >>>> >>>> Please consider the environment before printing this e-mail. >>>> >>>> ________________________________________ >>>> From: si-list-bounce@xxxxxxxxxxxxx [si-list-bounce@xxxxxxxxxxxxx] On >>>> Behalf Of vinod ah [ah.vinod@xxxxxxxxx] >>>> Sent: Saturday, January 07, 2012 12:27 AM >>>> To: SI-LIST >>>> Subject: [SI-LIST] DDR3 clock failing radiation Tests >>>> >>>> Hi all, >>>> I am facing problems related to EMI. I am having a ASIC with 2 DDR3 >>>> controllers running at 513MHz clock. I am interfacing 2 memories to each of >>>> the controller. So totally 4 memory chips on board, all running at 513MHz >>>> clock. During pre-compliance radiation testing in FCC certified lab, we >>>> observed 513MHz in the spectrum with 15dB above the CISPR class B limits >>>> i.e. test failing by 15dB !!!!! >>>> >>>> I tried to corelate this result with Hyperlynx spectrum analyzer simulation >>>> and SI simulation. The waveforms and radiation level looks fine in >>>> Hyperlynx i.e. no issues seen. Initially i had suspected the layout, but >>>> hyperlynx SI simulation looks fine and also the clock & dqs waveforms in >>>> CRO looks fine i.e. no ringing/overshoot etc. The DDR3 clock is routed in >>>> inner layer 3 of six layer stack up of the board. >>>> >>>> I have tried using EMI shield, but still i am failing by 8dB. Only thing i >>>> have not yet tried is spread spectrum clocking. But I am unable to find the >>>> source of problem. Can you please help me out in finding the sourceto this >>>> problem. >>>> >>>> I understand that it is very tuff to provide solution to this problem >>>> without seeing the layout, but i am expecting some tips so that i can move >>>> ahead in debugging the problem. >>>> >>>> Regards >>>> Vinod A H >>>> >>>> >>>> ------------------------------------------------------------------ >>>> To unsubscribe from si-list: >>>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field >>>> >>>> or to administer your membership from a web page, go to: >>>> //www.freelists.org/webpage/si-list >>>> >>>> For help: >>>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field >>>> >>>> >>>> List technical documents are available at: >>>> http://www.si-list.net >>>> >>>> List archives are viewable at: >>>> //www.freelists.org/archives/si-list >>>> >>>> Old (prior to June 6, 2001) list archives are viewable at: >>>> http://www.qsl.net/wb6tpu >>>> >>>> >>>> >>>> ------------------------------------------------------------------ >>>> To unsubscribe from si-list: >>>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field >>>> >>>> or to administer your membership from a web page, go to: >>>> //www.freelists.org/webpage/si-list >>>> >>>> For help: >>>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field >>>> >>>> >>>> List technical documents are available at: >>>> http://www.si-list.net >>>> >>>> List archives are viewable at: >>>> //www.freelists.org/archives/si-list >>>> >>>> Old (prior to June 6, 2001) list archives are viewable at: >>>> http://www.qsl.net/wb6tpu >>>> >>>> >>> >>> ------------------------------------------------------------------ >>> To unsubscribe from si-list: >>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field >>> >>> or to administer your membership from a web page, go to: >>> //www.freelists.org/webpage/si-list >>> >>> For help: >>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field >>> >>> >>> List technical documents are available at: >>> http://www.si-list.net >>> >>> List archives are viewable at: >>> //www.freelists.org/archives/si-list >>> >>> Old (prior to June 6, 2001) list archives are viewable at: >>> http://www.qsl.net/wb6tpu >>> >>> >> >> ------------------------------------------------------------------ >> To unsubscribe from si-list: >> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field >> >> or to administer your membership from a web page, go to: >> //www.freelists.org/webpage/si-list >> >> For help: >> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field >> >> >> List technical documents are available at: >> http://www.si-list.net >> >> List archives are viewable at: >> //www.freelists.org/archives/si-list >> >> Old (prior to June 6, 2001) list archives are viewable at: >> http://www.qsl.net/wb6tpu >> >> > > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > List technical documents are available at: > http://www.si-list.net > > List archives are viewable at: > //www.freelists.org/archives/si-list > > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > > ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu