RE: Probing power plane with analyser
Thankyou to all those who responded to my probing question. My initial response to the engineer was to try and characterise the board using near field probes however he is intent on looking directly at the 3v power rail. Given this, my primary concern is with protecting the analyser. Since his frequencies of interest extend to 300MHz, the LISN is not much of an option. The testing will initially only involve A:B comparisons so I feel satisfied that it should be safe enough to proceed with the DC blocking capacitor method. Regards, Cameron O'Phee. EMC & Safety Precompliance. Aristocrat Technologies Australia. Telephone : +61 2 9697 4420 Facsimile : +61 2 9663 1412 Mobile : 0418 464 016 --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Probing power plane with analyser.
Yes, Not only will the LISN have poor performance above 100 MHz, but the CISPR voltage probe or a "down and dirty" series capacitance will have trouble at these frequencies, although they will all work well at lower frequencies. Many of the other suggestions from members on this subject can be used to measure higher frequencies. As is invariably the case in this business, the "correct" answer depends on the frequency range of concern and the problem actually trying to be identified. Usually for the higher frequencies I use field probes along the board or cables rather than contact, sometimes adding short wires as "intentional unintentional" radiators. Paul McCoy chasgra...@aol.com@ieee.org on 09/29/2000 02:17:49 PM Please respond to chasgra...@aol.com Sent by: owner-emc-p...@ieee.org To: pwmc...@ra.rockwell.com, O'p...@ali.com.au cc: emc-p...@majordomo.ieee.org, seif...@ali.com.au Subject: Re: Probing power plane with analyser. Hi there - The AC LISN will have a very poor performance above about 100MHz don't you think?? --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Probing power plane with analyser.
Hi there - The AC LISN will have a very poor performance above about 100MHz don't you think?? --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Fwd: Probing power plane with analyser.
From: "Douglas C. Smith" List-Post: emc-pstc@listserv.ieee.org Date: Thu, 28 Sep 2000 12:09:12 -0700 A Balanced Coaxial probe is ideally suited for this. You can build it (see http://www.dsmith.org/pdf/cd94scr.pdf) or buy one from Fisher Custom Communications. Doug --- ___ _ Doug Smith \ / ) P.O. Box 1457 = Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-( ) | o |Email: d...@dsmith.org \ _ /]\ _ / Website: http://www.dsmith.org --- ___ Free Unlimited Internet Access! Try it now! http://www.zdnet.com/downloads/altavista/index.html ___ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Probing power plane with analyser.
From: "Bob Lewandowski" Picosecond Pulse Labs (www.picosecond.com) manufactures coaxial DC blocks that operate from 700 Hz to >26 GHz (3 dB BW) and stand off 16 Vdc. You can also get a .086 in. diameter 'Semi Flex' coax cable from Tensolite/QMI (www.qmiinc.com). It has tin dipped bare outer braid and is more flexible than conventional semi-rigid coax. Cut the cable, strip back the outer shield and dielectric to expose about 0.1" of center conductor, solder the coax shield to the ground pad of a bypass capacitor location, and the center conductor to the capacitor pad connected to the power bus. Then insert the dc block ahead of the 8591E and look at the spectrum of the noise on the bus. You can also measure bus impedance as a function of frequency by connecting a network analyzer to the same point by using a Smith Chart plot of S11. Calibrating the NWA and establishing the correct reference plane can be somewhat tricky in this process. The inductance of the traces and vias connecting the coax to the power and ground planes limit the low end measurement range at higher frequencies, but it may yield a useful comparison. --- From: "Raza, Ishfaqur" There is a HP Blocking capacitor, Model 10240B. It has BNC connections. I have used it in series with regular cables going to a spectrum analyzer to see the HF components on different surfaces. The component has 200V maximum DC tolerance. -- From: Nitin Bhandari You might want to try to use a DC blocking capacitor in series with the probe. This will protect your analyzer input and still provide you with the information that you want - the noise spectrum. From: "Bob Weber" To make measurements like this with a 'scope or spectrum analyzer, I solder a thin coax (like RG-178) to the PCB where I want to make the measurement. Use vias to the planes that are near each other and unused by other components. Solder the shield directly to the gnd via, and solder the center conductor to the power plane via thru a 100nf SMT cap (overall lead must be very short). RG-178 with the TFE dielectric and FEP jacket lets you solder right on the coax without melting the insulation. Put a BNC or Type-N connector on the other end, and connect to the equipment of your choice (make sure there is an internal or external termination). Secure the coax to the board so that the vias are not stressed (or ripped off) by moving the cable. You can also use the same setup to inject noise into the plane with a signal generator and see what frequencies and noise levels cause the board to malfunction. = ___ Free Unlimited Internet Access! Try it now! http://www.zdnet.com/downloads/altavista/index.html ___ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Probing power plane with analyser.
Cameron, Checkout Doug Smith's webpage for some insight on making RF measurements using various (homemade) probes. http://emcesd.com/ Good Luck, George -Original Message- From: Cameron O'phee [mailto:O'p...@ali.com.au] Sent: Wednesday, September 27, 2000 8:59 PM To: 'EMC - PSTC Forum' Cc: Roman Seifert Subject: Probing power plane with analyser. Hello All, I have been asked by one of our design engineers if I can measure the RF signature on the 3v plane on one of our PCB designs. The purpose of this is to compare it to proposed changes for cost reduction, ie removal of bypass caps. I would assume I need some sort of CDN but I have no designs for this application. Does anyone have any ideas on how I can safely probe a 3v DC power rail with an EMC analyser (HP8591E)? Regards, Cameron O'Phee. EMC & Safety Precompliance. Aristocrat Technologies Australia. Telephone : +61 2 9697 4420 Facsimile : +61 2 9663 1412 Mobile : 0418 464 016 --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Probing power plane with analyser.
We made a probe using rigid coax with its built in SMA connector. Solder a pin to the side of the coax and file it diagonally to create a sharp point. To increase the loading impedance we used an SMA "collar" that had been filed out to place a series chip resistor of 470 ohms in series with the center conductor. Then we "calibrated" the probe for insertion loss up to 2 GHz and could probe around on the board. If I had it to do again, I would move the resistor out very close to the probe tip to reduce the effects of the series inductance, but what worked worked, so we went on. - Robert - -Original Message- From: pwmc...@ra.rockwell.com To: Cameron O'phee Cc: 'EMC - PSTC Forum' ; Roman Seifert List-Post: emc-pstc@listserv.ieee.org Date: Thursday, September 28, 2000 5:50 AM Subject: Re: Probing power plane with analyser. > > >Cameron, > If you are looking for a measure of the conducted RF coming off the >board the standard AC LISN works for DC power as well. The voltage probe >per CISPR 16 will also work and gives a standardized impedance that can be >probed from point to point (or if you are looking for a "down and dirty" >measurement just put a capacitor in series with your probe to block the >DC). > >Paul McCoy > > > > > >"Cameron O'phee" @ieee.org on 09/27/2000 07:59:24 PM > >Please respond to "Cameron O'phee" > >Sent by: owner-emc-p...@ieee.org > > >To: "'EMC - PSTC Forum'" >cc: Roman Seifert >Subject: Probing power plane with analyser. > > > >Hello All, > >I have been asked by one of our design engineers if I can measure the RF >signature on the 3v plane on one of our PCB designs. The purpose of this >is >to compare it to proposed changes for cost reduction, ie removal of bypass >caps. I would assume I need some sort of CDN but I have no designs for >this >application. Does anyone have any ideas on how I can safely probe a 3v DC >power rail with an EMC analyser (HP8591E)? > > >Regards, > >Cameron O'Phee. >EMC & Safety Precompliance. >Aristocrat Technologies Australia. > >Telephone : +61 2 9697 4420 >Facsimile : +61 2 9663 1412 >Mobile : 0418 464 016 > >--- --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Probing power plane with analyser.
Cameron: That's fairly easy to do as long as you: 1. Take all measurments from the same reference points before and after the changes and 2. Use a DC block on the input to the analyzer ;other wise you may have an expensive input to replace. Most analyzers inputs are not protected for DC. Most companies sell the DC isolator as an accessory. Ralph Cameron EMC Consultant and Suppression of Consumer Electronic Equipment. - Original Message - From: "Cameron O'phee" To: "'EMC - PSTC Forum'" Cc: "Roman Seifert" Sent: Wednesday, September 27, 2000 8:59 PM Subject: Probing power plane with analyser. > > Hello All, > > I have been asked by one of our design engineers if I can measure the RF > signature on the 3v plane on one of our PCB designs. The purpose of this is > to compare it to proposed changes for cost reduction, ie removal of bypass > caps. I would assume I need some sort of CDN but I have no designs for this > application. Does anyone have any ideas on how I can safely probe a 3v DC > power rail with an EMC analyser (HP8591E)? > > > Regards, > > Cameron O'Phee. > EMC & Safety Precompliance. > Aristocrat Technologies Australia. > > Telephone : +61 2 9697 4420 > Facsimile : +61 2 9663 1412 > Mobile : 0418 464 016 > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Jim Bacher: jim_bac...@mail.monarch.com > Michael Garretson:pstc_ad...@garretson.org > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > > > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Probing power plane with analyser.
Cameron, If you are looking for a measure of the conducted RF coming off the board the standard AC LISN works for DC power as well. The voltage probe per CISPR 16 will also work and gives a standardized impedance that can be probed from point to point (or if you are looking for a "down and dirty" measurement just put a capacitor in series with your probe to block the DC). Paul McCoy "Cameron O'phee" @ieee.org on 09/27/2000 07:59:24 PM Please respond to "Cameron O'phee" Sent by: owner-emc-p...@ieee.org To: "'EMC - PSTC Forum'" cc: Roman Seifert Subject: Probing power plane with analyser. Hello All, I have been asked by one of our design engineers if I can measure the RF signature on the 3v plane on one of our PCB designs. The purpose of this is to compare it to proposed changes for cost reduction, ie removal of bypass caps. I would assume I need some sort of CDN but I have no designs for this application. Does anyone have any ideas on how I can safely probe a 3v DC power rail with an EMC analyser (HP8591E)? Regards, Cameron O'Phee. EMC & Safety Precompliance. Aristocrat Technologies Australia. Telephone : +61 2 9697 4420 Facsimile : +61 2 9663 1412 Mobile : 0418 464 016 --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Probing power plane with analyser.
Hello All, I have been asked by one of our design engineers if I can measure the RF signature on the 3v plane on one of our PCB designs. The purpose of this is to compare it to proposed changes for cost reduction, ie removal of bypass caps. I would assume I need some sort of CDN but I have no designs for this application. Does anyone have any ideas on how I can safely probe a 3v DC power rail with an EMC analyser (HP8591E)? Regards, Cameron O'Phee. EMC & Safety Precompliance. Aristocrat Technologies Australia. Telephone : +61 2 9697 4420 Facsimile : +61 2 9663 1412 Mobile : 0418 464 016 --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
