[SI-LIST] Re: Simulationsof a connector
- From: christopher.heard@xxxxxxxxxxxx
- To: michael.kurten@xxxxxxxxxxxxxxx
- Date: Mon, 20 Jan 2003 19:59:55 -0500
It is likely that your 6x6 coupled SPICE model and the vias are not a
perfect match to 50 ohms, therefore there will be reflections from portions
of the connector and from the vias at the launches. A sine function of
5GHz sounds like a connector propagation delay of about 1/5E9 = 200pS,
fairly typical of the delay from one via to another.
Chris
**********************
Chris Heard
Teradyne
Work: 603-879-1031
Cell: 508-277-5780
Email: christopher.heard@xxxxxxxxxxxx
"Michael Kurten"
<michael.kurten@server To: Si-List
<si-list@xxxxxxxxxxxxx>
works.com> cc:
Sent by: Subject: [SI-LIST]
Simulationsof a connector
si-list-bounce@freelis
ts.org
01/20/2003 06:14 PM
Please respond to
michael.kurten
I'm simulating a connector (6x6 coupled spice model) with HSPICE to
determine the crosstalk caused by the connector. The connector is connected
to one active line, 14 quiet lines, and the remaining 21 pins are grounded.
* topology of the active line
*
* source 50Ohm 50Ohm 50Ohm 50Ohm 50ohm
* |>--/\/\/----=========----{CONNECTOR}
-------=========---/\/\/--|gnd_a
* | | |
* = = \ 1e6Ohm
* | | /
* gnd | |
* | gnd
* |
* gnd_a
* topology of the quiet lines
*
* gnd 50Ohm 50Ohm 50Ohm 50Ohm 50Ohm
* |---/\/\/----=========----{CONNECTOR}
----=========---/\/\/--|gnd_a
* | |
* = =
* | |
gnd gnd_a
The active line is excited by a single rising edge with a rise time of
500ps.
The transmission lines are all 50 Ohm T-element
The capacitors at the left and right side of the connector have a value of
1.0pF
The grounded pins are connected directly to ground via a 1m resistor in
parallel with a 1.0pF capacitor
The results on the quiet lines show the crosstalk followed by an
establishing sine function which decays very slowly. The frequency of the
sine function is in the 4-5 GHz range.
I'm trying to understand where this behavior comes from. I tried a couple
of
arrangements to get rid of this sine function but none of them changed the
behavior significantly. E.g. option gshunt and cshunt, connecting gnd and
gnd_a via a high impedance resistor and a small capacitor.
Any help is highly appreciated.
Regards
Michael
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