[SI-LIST] Re: Power and ground noise measurement.

Hi Moore,

You can find lots of tips at my site under the "Technical Tidbits"
section (http://www.dsmith.org).

In general, do not trust data sheets of measurement apparatus. For
instance, one active differential probe, 1.5+ GHz bandwidth, I recently
measured had a 18 Ohm (!) input impedance at 1.2 GHz when using a small
probing tip with very short leads. This is a typical result for active
probes. Input capacitances of "<1 pf" are way to high for high frequency
measurements.

One active probe used with its suppled hardware had a frequency response
that looked like a Cisco logo with a 20 dB peak in gain at about 400
MHz!

Many popular scopes have too much crosstalk between channels to be able
to measure digital signals on one channel and small analog signals on
anothe channel simultaneously.

I could go on all day along this line (and will on May 20th). The best
approach is to "think" about what you are doing in these measurements
and do not blindly trust your equipment or methods. Current measurement
apparatus can usually work, but the more expensive your measurement
apparatus, the more thought is required. The days of just picking a
probe off the bench and making a measurement are long gone.

Doug

"Moore Mo (modaochun)" wrote:
> 
> Hi all:
> 
>     I'm doing something about SI ,as you know, power and ground noise is very 
> important in high-speed digital design. My problem is how to analyze the 
> noise. Which software or tools is better? How to measure the noise(especial 
> ground bounce and ground noise) in the board? And how much the noise level we 
> can't stand ? Or could you tell me who do the best in this field?
> 
>     Thank you!
> 
> Best Regards
> 
> Moore MO (Modaochun)
> Huawei Technologies Co.,Ltd.
> Tel: 86 755 6540544/6540808
> Fax:86 755 6544730
> Email:modaochun@xxxxxxxxxx
> website: http: // www.huawei.com
> 
> ------------------------------------------------------------------
> 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:
> http://www.freelists.org/webpage/si-list
> 
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
> 
> List archives are viewable at:
>                 http://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
> 

-- 
-------------------------------------------------------
    ___          _       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:   doug@xxxxxxxxxx
 \ _ /    ]    \ _ /     Website: http://www.dsmith.org
-------------------------------------------------------
------------------------------------------------------------------
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:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List archives are viewable at:     
                http://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: