[SI-LIST] Re: Power Integrity measurement equipment
- From: Heinrich.Smith <heinrich.smith2005@xxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx, "Istvan Novak" <istvan.novak@xxxxxxx>
- Date: Tue, 28 Mar 2006 00:37:23 +0800
Thank you for your valuable introduction.
I still have some questions need your advice.
For modern IC design like CPU or FBDIMM architecture, the IO-buffer power
rail is different from core power rail,right?
Vio power rail has lower current driving but bringing higher frequency SSN
into PKG,PCB and , However,Vcore power rail has
higher current driving but the switching delta-I noise are enclosed inside
of IC(die).
From your experience,
PCB's pi decap solution should cover to ?MHz for Vio power rail.(for
example,data rate 800MHz)
PCB's pi decap solution should cover to ?MHz for Vcore power rail.
In my experiments,the ESR of deacp above 100MHz will be large
increasingly,For example ESR:100mohm,that mean we need 100 capacitors to
drop the impedance to 1mohm,
My meaning is it is a hard work to drop the Z-impedance easily at hundred
MHz range,Who can cover this range's pi issue?
PKG's decap could solve it? or die-cap could solve it? or make an embeded
capacitor on PCB?
The second question,
When i measure Z-impedance of the power delivery network,Should i turn on
VRM?
If not necessary, The resonant frequency will be shifted before and after
turning on VRM,right? which result is important for me?
Regards,
-Heinrich.Smith
2006/3/24, Istvan Novak <istvan.novak@xxxxxxx>:
>
> Heinrich,
>
> You need to start with the BW. The required instrument BW for power plane
> measurement depends on the excitation BW and maximum modal resonance
> frequency you want to care. If you know the signal rise/fall times
> hitting your
> planes, a simple BW=0.35/trise gives a good indication. The lowest
> parallel
> modal resonance frequency of a rectangular plane shape is F=1/(2*tpd)
> where tpd is the propagation delay along the longer side. Unless you have
> a very skinny narrow plane shape, the modal resonances usually blend into
> an inductive slope after the first few harmonics, so looking out to the
> tenth
> harmonic of the lowest modal parallel resonance is usually enough. For
> any
> power plane, if you are sure that you dont excite particular modal
> resonances,
> you dont need to worry about them, so you can take the smaller BW number
> of these two. You can plug in your numbers for each power rail, take the
> highest numbers you get and apply some safety cushion (at least an
> octave, 2x)
> to get the BW necessary for testing.
>
> In terms of VNA features, you need to make sure that the dynamic range
> is large
> enough if you plan on measuring mid to high-power systems, where the
> supply
> rail impedance is supposed to be low. At very low frequencies, when you
> want to measure the output impedance of DC-DC converters and/or
> large-capacitance and low-ESR bulk capacitors, you need to isolate the
> source and receive port returns, something that most VNAs dont offer
> today.
> Also, if you consider the entire frequency range that you need, which
> could
> range from Hz to GHz, you dont find any single instrument that would
> cover it.
> The same applies to cables and probes; those which are convenient for low
> frequency measurements are not optimum for GHz frequencies and vica versa.
>
> In terms of VNA model, you can check out the major VNA manufacturers:
> Agilent, Anritsu, Rohde Schwartz. You may also want to look at the VNA
> from
> Ultimetrix, which offers the DC blocking between input and output ports
> and
> an easy way to cascade VNAs to cover a wide frequency range.
>
> For more details you can check some of the posted papers on
> http://home.att.net/~istvan.novak/papers.html You can start with the
> two papers
> from DesignCon East 2003.
>
> Regards,
>
> Istvan Novak
> SUN Microsystems
>
>
>
>
> Heinrich.Smith wrote:
>
> >I would like to measure the power plane/capacitor impedance,Z.
> >I need which kind of VNA? how high BW?
> >which kind of the probe type? coaxial cable?
> >How to do the calibration?
> >Anyone could give me pictures or any documents ?
> >Thank you very much.
> >-Heinrich.smith
> >
> >
> >
> >
> >
>
>
------------------------------------------------------------------
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
Other related posts:
