[SI-LIST] Re: Circle bus topology
- From: ronald miller <ron@xxxxxxxxxxx>
- To: David.Carney@xxxxxxxxxx
- Date: Thu, 26 Jul 2007 07:49:27 -0700
Hi Dave
In microwave engineering a 5/4 wavelength rat-race is often used as a
mixer or power splitter
because it provides isolation between ports. It has 4 ports used, two
in and two out.
The basic principle that must be considered in your application is that
the power splits from an
input port and goes down each leg until they come together again. When
the two signals come together
again half way round the circle path they are both in phase and reflect
back as an open down both paths.
Now when you add various terminations on each path the problem becomes
more complex and
varies with the data pattern if the path length is longer than the data
rate period.
From an SI or EMI viewpoint the complex structure just adds another
level of complexity.
Military Aircraft used a lossy looping serial structure called 1553.
They recognized the difficulty
of reflections with a multi-drop loop and added attenuation at each
drop(port) and it worked well
but the system had to tolerate over 12 db of loss(i believe) from a
transmitting device to a receiving
device.
However, if you are willing to make lossy connections there is no need
to make a loop.
Ron Miller
David Carney (Neenah) wrote:
>Has anyone ever experimented with a circle bus topology. The basic
>concept would be a bus with several devices attached. They would be
>routed in a daisy chain topology, and then the two ends of the daisy
>chain would be connected together. The PCB routing would look like a
>circle or a loop for each net on the bus. Pointers to references such
>as papers or application notes would be greatly appreciated. I'm
>particularly interested in signal integrity and EMC implications of this
>topology.
>
>Thanks.
>
>
>----------
>David Carney
>Senior Hardware Engineer
>Plexus Corp.
>Phone - 920-751-5646
>
>------------------------------------------------------------------
>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:
>//www.freelists.org/webpage/si-list
>
>For help:
>si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>
>List technical documents are available at:
> http://www.si-list.net
>
>List archives are viewable at:
> //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
>
>
>
>
>
--
Ronald Miller
Ghz Data, Signal Integrity Consulting
7721 Sunset Ave.
Newark CA 94560
tel 510-793-4744
cell 510-377-9380
fax 510-742-6686
www.ghzdata.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:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//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:
