[SI-LIST] Re: [SI-LIST]: Design a shielded differential line

Olivier,

It all depends on how much coupling you want between the traces.  Please 
also be aware that it is usually much harder to control the coupling of 
broadside coupled diff. pairs than edge-coupled.  In a 1.5mm board a 
shielded 75 ohm structure will require a lot of horizontal spacing as in 
about 1.5mm ctr to ctr for 220 u tracks.

Regards,



At 04:15 PM 5/28/2002 +0200, PRIEUR, Olivier wrote:

>Dear All,
>
>I want to design a shielded differential line in a PCB.
>Nominal characteristic impedance of the differential line is 70 to 85 ohms
>The recherched struture is
>______________            GND
>        ___                  h1
>        ___                  h
>______________    h1   GND
>I have the added constraints:
>         minimum width W of trace is .216 mm
>         thickness h, h1 of dielectric is 0.1/0.2/0.3/0.4/0.5
>         substrate dielectric constant about 4.7 (FR4)
>I look for h, h1 and W.
>I want a minimum capacitance between the differential line and the ground.
>Do you know a formula, an article about this topic?
>
>Best regards,
>
>------------------------------------
>Olivier PRIEUR
>e-mail: olivier.prieur @astrium-space.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
>

------------------------------------------------------------------
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: