Dear Charles The 50 ohm input impedance of SA would not affect the PDS. Normally, the impedance of PDS is below 1 ohm, which is little compared with 50ohm. If the freqeuncy domain is extended above 3GHz, my method is not useful. There are some point to suggust. 1.There is a dc-block. If the frequency domain is below 2GHz, a very cheap dc-block could be made by PCB and discrete capacitor, which is about of $1.00:) A commerical dc-block is about of $100:( 2.The "pigtail" effect should be awared. The pigtail should be as short as possible. I hope this is helpful. I am also trying to corelate the measurement in time domain and frequency domain. I have not get any success:( In SA maesurement, there is no phase information. Another problem is "what is measured by SA?" I have found that some kinds of noise could not be caught by SA. Best Regards Zhangkun 2005.1.5 ----- Original Message ----- From: "Grasso, Charles" <Charles.Grasso@xxxxxxxxxxxx> Date: Wednesday, January 5, 2005 10:38 pm Subject: RE: [SI-LIST] Re: Article discussion on bad packages - core power measurments > Dear Zhangun > > I am intrigued by your last email. In it you mentioned that: > "I measured the CORE power ground noise by spectrum analyzer...." > > I very interested in your experiences as I have tried to correlate > SA power measurements with scope measurements with minimal success. > One problem I think is that a SA has a 50ohm input impedance that > can load the PDS and the coax needed to hook up the SA will add > how hf filtering, > > Would you share with us some thoughts on how to use a SA for > power measurements ?? > > Thanks! > > Best Regards > Charles Grasso > Senior Compliance Engineer > Echostar Communications Corp. > Tel: 303-706-5467 > Fax: 303-799-6222 > Cell: 303-204-2974 > Pager/Short Message: 3032042974@xxxxxxxx > Email: charles.grasso@xxxxxxxxxxxx; > Email Alternate: chasgrasso@xxxxxxxx > > > > -----Original Message----- > From: zhangkun 29902 [zhang_kun@xxxxxxxxxx] > Sent: Wednesday, January 05, 2005 7:29 AM > To: weirsp@xxxxxxxxxx > Cc: hmurray@xxxxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: Article discussion on bad packages - core > > > Steve: > > I agree with you according to my experience. In some product in my > company,I measured the CORE power ground noise by spectrum > analyzer. There is some > great power consuming for several MHz to dozens of MHz. This kind > of power > ground noise give rise to system failure. The solvment is to add a > lot of > discrete decoupling capacitor, which is very simple:) > > If there is any problem with IO power, it is very difficult to > solve them. > There is also critical SSN problem. > > Larry: > > Why do you seperate the SSN and PI problem? I think they should be > considered together. > > Best Regards > > Zhangkun > 2005.1.5 > > ----- Original Message ----- > From: steve weir <weirsp@xxxxxxxxxx> > Date: Wednesday, January 5, 2005 7:07 pm > Subject: [SI-LIST] Re: Article discussion on bad packages - core > > > Hal, I have generally found that the FPGA core power is not a > > serious > > challenge. In general ( beware generalizations! ) I have found > > the I/O > > rails tend to suffer much more percentage bounce and need much > > more care > > and attention than the core, even though the core is lower > > voltage. There > > are a number of reasons for this: fewer attachments, little in- > > package / > > on-die capacitance for I/O, sparse ground chevron, tendency to > cut- > > up I/O > > power planes, etc, etc. The single most important design issue > in > > my mind > > is planning I/Os to contain the peak value of simultaneous > > switching di/dt > > within the package capabilities. > > > > For your toolbox code, you might consider using the clock > > multiplexers > > available for several years now. > > > > For I/O rather than build a special test load, I suggest including > > a > > multiplexor to all output IOBs that has as its second input a > > simple > > pattern generator as part of the production design. Attaching > the > > mux > > control to a scan chain, or host register makes probing with > > otherwise > > realistic conditions much easier, and avoids code maintenance > > headaches. You can stay as simple or get as fancy as you like > > with this > > technique without consuming much area, or imposing much timing > > penalty. > > I don't have a good answer for CPU code. > > > > Steve. > > > > At 01:55 AM 1/5/2005 -0800, Hal Murray wrote: > > > > > > The most crucial piece of information from the chip > > manufacturer is > > > > the maximum and minimum currents that can be drawn from the > > PCB PDS. > > > > This establishes the dI or transient current that the PCB must > > supply.> > The rise time (dt) is determined by the low pass > > filter associated > > > > with the chip/package resonant frequency. Generally, customer > > code> > will determine the current waveform and therefor the > > frequency profile > > > > of the current drawn by the chip, so I don't believe it is > > fair to ask > > > > chip vendors for the power spectrum. However, they should > be > > > > obligated to give their customers the maximum and minimum > > current that > > > > their chip will ever draw. The minium I is probably > > determined by > > > > sleep mode and power saving states. > > > > > >Is is possible to give useful numbers for min/max currents on > > modern chips? > > > > > >Consider a CPU: What code is it running? > > > > > >Consider a FPGA: A nasty design can use many times the normal > > peak current > > >for a short burst without cooking itself. (Adjust duty cycle > to keep > > >temperature reasonable.) > > > > > >I occasionally scheme about writing some code that would try to > > go from min > > >to max power usage and adjust the timing to see if I can provoke > > troubles in > > >the PDS. Or something else will break. This seems like a > > generally nasty > > >sort of code to have in your toolbox. > > > > > >I'm thinking of something like keep all memories active for N > > cycles, then do > > >nothing for N cycles. Repeat for a while, then try the next N. > > Finding the > > >really nasty cases would probably take help from one of the > > chip/system>designers/architects. How do you keep all the ALUs > > and memories busy? > > > > > >Maybe the leakage through thin oxides will save us by making the > > min current > > >large enough so that the ratio of min:max is reasonable. :) > > > > > >Worst case might be coming out of reset. > > > > > > > > > > > > > > >-- > > >The suespammers.org mail server is located in California. So are > > all my > > >other mailboxes. Please do not send unsolicited bulk e-mail or > > unsolicited>commercial e-mail to my suespammers.org address or any > > of my other addresses. > > >These are my opinions, not necessarily my employer's. I hate spam. > > > > > > > > > > > >---------------------------------------------------------------- > -- > > >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 FAQ wiki page is located at: > > > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > > > > > >List technical documents are available at: > > > http://www.si-list.org > > > > > >List archives are viewable at: > > > //www.freelists.org/archives/si-list > > >or at our remote archives: > > > http://groups.yahoo.com/group/si-list/messages > > >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 FAQ wiki page is located at: > > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > > > > List technical documents are available at: > > http://www.si-list.org > > > > List archives are viewable at: > > //www.freelists.org/archives/si-list > > or at our remote archives: > > http://groups.yahoo.com/group/si-list/messages > > 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 FAQ wiki page is located at: > http://si-list.org/wiki/wiki.pl?Si-List_FAQ > > List technical documents are available at: > http://www.si-list.org > > List archives are viewable at: > //www.freelists.org/archives/si-list > or at our remote archives: > http://groups.yahoo.com/group/si-list/messages > 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu