[SI-LIST] Re: Eye width for microstrip and stripline configuration in PCIE gen2 simulation.
- From: "Alfred P. Neves" <al@xxxxxxxxxxxxxxxxx>
- To: si-list <si-list@xxxxxxxxxxxxx>
- Date: Thu, 21 Feb 2013 10:13:50 -0800
When we compare eye diagrams in either 3D EM simulation or measurement (VNA or
differential TDR) in addition to simple loss, SDD21, we analyze:
1. simple pulse response, rise time response, ringing, reflections, etc.,
2. SDD11, differential return loss
3. group delay variation of SDD21
If your input PRBS or NRZ data signal is not a clean gaussian pulse response,
but is a ragged PWL sampled system, your eye will appear worse with the wider
bandwidth system.
Run a clock pattern with the same rise times, that is 1/5 the data rate and
compare the simulation results is another suggestion.
Products for the Signal Integrity Practitioner
Alfred P. Neves
Chief Technologist
Office: 503-679-2429
www.wildrivertech.com
On Feb 21, 2013, at 10:00 AM, Joseph.Schachner@xxxxxxxxxxxxxxxxxx wrote:
> microstrip, because it is not sandwiched between ground planes, is more
> susceptible to crosstalk than stripline. Cross talk might be the cause of
> more eye closure with microstrip.
> Another likely cause is that with microstrip the electromagnetic field
> exists both above the microstrip (in the air) and below it (in the
> substrate). That non-homogeneous medium makes the dielectric constant
> vary with frequency which means it is dispersive - the phase velocity
> decreases with increasing frequency. That pulls fast edges apart. And,
> the characteristic impedance changes with frequency ... I don't remember
> exactly how to describe that. These effects can be small depending on
> usage, but one thing is certain: they will contribute to eye closure for
> microstrip and they basically do not exist for stripline.
>
> Insertion loss is not the only thing that needs to be considered.
>
> --- Joe S.
>
>
>
> From: Siddharth Rajagopalan <maxsidhu@xxxxxxxxx>
> To: si-list@xxxxxxxxxxxxx, "Moran, Brian P" <brian.p.moran@xxxxxxxxx>
> Date: 02/21/2013 11:24 AM
> Subject: [SI-LIST] Eye width for microstrip and stripline
> configuration in PCIE gen2 simulation.
> Sent by: si-list-bounce@xxxxxxxxxxxxx
>
>
>
> Dear experts,
> I am currently working on a PCIE gen2 simulation. I am evaluating both the
> microstrip and the stripline configurations.As expected, the stripline
> configuration yields more insertion loss than the microstip one. This
> however is not reflected in the eye diagram since the stripline has a
> better eye width than the microstrip one. I was of the understanding that
> higher insertion loss manifests itself as higher rise time degradation in
> the time domain. I might exposing my ignorance in the previous statement.
> kindly help me clarify this.
> Thanks,
> siddharth rajagopalan
>
>
> ------------------------------------------------------------------
> 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 forum is accessible at:
> http://tech.groups.yahoo.com/group/si-list
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
>
> 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:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>
> List forum is accessible at:
> http://tech.groups.yahoo.com/group/si-list
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
>
> 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:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
