Ken, another really good alternative is the Signal Hound USB based analyzer for $919. From 100Hz to 3.3GHz it goes down to -135dB, and it is usable from 1Hz to 4.4GHz. http://www.signalhound.com/ Best Regards, Steve On 1/7/2012 4:23 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 > > > -- Steve Weir IPBLOX, LLC 150 N. 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