[SI-LIST] Re: Power Integrity measurement equipment

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
>
>
>
>  
>

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