[SI-LIST] Re: DC-26 GHz Picoprobe

Neven, my experience with FET probes is that because very little charge is 
transferred, they can offer decent response with just the tip connection, 
provided there is a low frequency return path between the scope signal 
ground and the DUT common, but it isn't perfect by a long shot.
For the best accuracy, I would encourage strapping to the coax shield where 
it emanates from the probe base a connection to DUT common, and then 
possibly adding a CM ferrite around the coax back to the scope.  One way to 
effect that would be to insert a coax "T" and drill out the inner conductor 
on the tap.

For that incredible 0.05pF number I assume that they are using a well 
balanced JFET front-end with PTFE insulation.

Doug Smith may have more information that is useful.

Regards,


Steve.
At 05:13 PM 3/25/2004 +0000, you wrote:
>Hello,
>
>Is anyone on the list using GGB Industries' active probes e.g.
>
>www.ggb.com/35.html ?
>
>For this Model 35 probe, they claim DC-26 GHz response with 1.25
>MOhm nominal resistance in parallel with 0.05 pF.
>
>They also claim that the probe uses single-point probe tip only (no
>reference point)!! Since voltage is field integral between two
>points in space, I have problem with this claim. Has anyone verified
>the performance? They don't want to disclose the base for that
>claim, saying it is proprietary information. Hm....
>
>I still thinik the probe might be pretty good in a differential
>configuration with two probes used, but I would appreciate any on-
>line or off-line feedback if you use it.
>
>Thanks, Neven
>
>------------------------------------------------------------------
>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 FAQ wiki page is located at:
>                 http://si-list.org/wiki/wiki.pl
>
>List technical documents are available at:
>                 http://www.si-list.org
>
>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
>

Steve Weir
Teraspeed Consulting Group LLC
2926 SE Yamhill St.
Portland, OR 97214
(503) 239-5536
http://www.teraspeed.com
------------------------------------------------------------------------------------------------------
Teraspeed(SM) is the service mark of Teraspeed Consulting Group LLC


------------------------------------------------------------------
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 FAQ wiki page is located at:
                http://si-list.org/wiki/wiki.pl

List technical documents are available at:
                http://www.si-list.org

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: