Also Ken here's an English version explaining the concept somewhat...
http://www.sonnetusa.com/products/lite/liteapps.asp
Microwave circuits are fascinating... :)
Bill Brooks - KG6VVP
PCB Design Engineer, C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
Datron World Communications, Inc.
_______________________________________
San Diego Chapter of the IPC Designers Council
Communications Officer, Web Manager
http://dcchapters.ipc.org/SanDiego/
http://pcbwizards.com
-----Original Message-----
From: Kanaiyalal Patel [mailto:[log in to unmask]]
Sent: Wednesday, June 08, 2005 8:47 AM
To: TechNet E-Mail Forum; Brooks,Bill
Subject: Re: [TN] stubbing in circuit design?
Thanks Bill. You cleared my question.
Re,
Ken Patel
--- "Brooks,Bill" <[log in to unmask]> wrote:
> I can't read this web page I am linking here too
> well (it's in some oriental
> language) but it has a great illustration of a
> 'stub' in a RF circuit....
> down quite a way on the page...
> http://www.rfdh.com/bas_rf/begin/smith6.htm
>
>
> I understand that Valor detects these features in
> the circuit and will
> notify the CAM operator of their locations in the
> circuit... Some CAD
> systems do this as well.
>
> In Microwave circuits these are used to 'tune' the
> circuit... in High Speed
> design they are typically avoided because of the
> trouble they cause with
> signal integrity.
>
> A stub is loosely defined as an un-terminated
> transmission line... or one
> without a load at the end of it to be driven by a
> signal... They make great
> signal reflectors and can cause havoc with digital
> signals...
>
> But they are not ALL BAD...In Microwave circuits
> they can be used
> effectively to match the impedance of a transmission
> line or act as a
> printed component of the RF circuit.
>
> I think the item you were reading about where they
> say to 'avoid stubs' was
> related to the bad effects they can have on digital
> signal integrity.
>
> Best regards,
>
> Bill Brooks - KG6VVP
> PCB Design Engineer, C.I.D.+, C.I.I.
> Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
> Datron World Communications, Inc.
> _______________________________________
> San Diego Chapter of the IPC Designers Council
> Communications Officer, Web Manager
> http://dcchapters.ipc.org/SanDiego/
> http://pcbwizards.com
>
> -----Original Message-----
> From: Dave Seymour
> [mailto:[log in to unmask]]
> Sent: Wednesday, June 08, 2005 7:26 AM
> To: [log in to unmask]
> Subject: Re: [TN] stubbing in circuit design?
>
> Ken,
>
> When designing a PCB, the engineers talk about
> "Stubs" as a "T" in the
> signal route.
>
>
> o------------o------------o This is daisy chain.
>
> o------------o-----------o
> |
> |
> |
> o
> This is a "Stub" or "T".
>
>
> Depending on the frequency ( rising edge) of the
> signal, reflections could
> create false triggering of the circuit.
>
> Stubs are impossible to design out 100%, think about
> pin escapes, or
> wire bonds
> on the IC itself. However, the length of the stub
> is can be critical.
>
> Do some google searches on signal integrity or high
> speed design.
>
> Hope this helps,
>
> Dave
>
>
>
>
> Dave Simonik wrote:
>
> >Could this be referencing the plated hole wall
> remaining above the Must Not
> >Cut (MNC) layer after Back Drilling on back planes?
> This is normally
> >referred to as the 'Stub'.
> >
> >Dave Simonik
> >Sanmina SCI
> >Owego NY Division
> >
> >-----Original Message-----
> >From: Kanaiyalal Patel
> [mailto:[log in to unmask]]
> >Sent: Wednesday, June 08, 2005 9:54 AM
> >To: [log in to unmask]
> >Subject: stubbing in circuit design?
> >
> >
> >All,
> >What is stubbing in PCB circuit design? Can some
> one
> >send me a picture or link to visulize it?
> >
> >Re,
> >Ken Patel
> >
> >
> >
>
> --
> Dave Seymour, CID+
> Catapult Communications Inc.
> 800 Perimeter Park Dr, Suite A
> Morrisville, NC 27560
>
> Direct: (919)653-4249
> Main: (919)653-4180
> Fax: (919)653-4297
>
> [log in to unmask]
>
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