[SI-LIST] Re: HSPICE query
- From: kevin.voegele@xxxxxxxxxxxxxxxx
- To: <kiran.kumar10@xxxxxxxxx>
- Date: Tue, 19 Jun 2012 11:19:15 -0500
Kiran,
What is the length of the transmission line in the simulation? If you can
insert a 100 Ohm differential impedance line in the path you may spread
apart the high frequency constructive/destructive peaks in the S11 (or
S22) results. I am thinking your data comes from a test board so there is
a PCB trace in the measurement. If you built your test bench without this
T-line, then you will have very high frequency "noise" in the return loss.
L ~ C/2(SQRT (Er)*delta F
So if length of the T-line in your test bench is very short (like package
only) then the delta frequency between constructive and destructive
interference will be low and appear as "noise" as you describe.
I would insert a W-element model in the path, after the package to the
port to add length to make the delta F higher. Make it 10 cm or longer.
You can adjust this length until you match the insertion loss curve you
received. Then you will know the test board topology used to make the
measurement in the first place.
Of course I may not completely understand your issue in the first place
but it sounds familiar.
Regards,
Kevin
*******************************************************
Kevin Voegele
Design Engineering Manager
Toshiba America Electronic Components, Inc
Minneapolis Design Center
ph. 952.842.2476 FAX 952.893.8031
cell 952.334.1015
e-mail: kevin.voegele@xxxxxxxxxxxxxxxx
*******************************************************
From: <kiran.kumar10@xxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>,
Date: 06/19/2012 01:13 AM
Subject: [SI-LIST] HSPICE query
Sent by: <si-list-bounce@xxxxxxxxxxxxx>
Hi,
I am working on a project that uses a 6-pair X 4-wafer connector with 24
differential pairs of 100Ohms differential impedance. Vendor provided a
single ended S-parameter connector model for the same.
When I use HSPICE port element(P-element) and .LIN command to convert the
single ended parameter to differential and plot the Return Loss in Custom
Waveview, I am getting very bad noise in the frequency range up to 10G
(noise frequency of 100MHz). But if I use the original single ended
S-parameter file directly and use port conversion formula (eg. S11DD=
S11-S13+S31+S33 for each port) Then I am getting a clean Return Loss plot
as the plot provided by the vendor.
The port conversion using P-element is introducing noise in the generated
differential S-parameter model.
Can someone help me get around this issue?
Please revert back if the question is not clear.
Thanks in advance.
Best Regards,
Kiran
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