CPW Simulation in ADS

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sool83

Joined: 09 Jul 2008
Posts: 1

09 Jul 2008 22:24 ads cpw

Hi everybody!

I need to simulate some microwave circuits in coplanar waveguides by using ADS Momentum 2006. I prefer to use STRIPs instead of SLOTs even thought simulation is demonstrated to be more efficient with SLOTs, since I generally start from masks or .gds file.Then, I use 2 metallic strips as ground planes and one strip between them as RF line. I set two opposite ports as "internal" and the other two couples of ports as "ground reference", obviously referred to the rispective internal port.

I noticed that S-parameters results from a full wave simulation of a simple 50 ohm CPW (for istance, 1 mm of length) are different from the CPW lumped element provided by the schematic tool of ADS. These results are different also from measurement results!!! In fact, I usually try to simulate a complex structure in Momentum (i.e. suspended bridge, discountinuities, transitions, ecc..) and it seems to be coherent with measured data, but if there are some simple CPW path, I need to simulate the whole structure by exporting full-wave S-parameters in the Schematic and by adding CPW lumped elements where needed, rather than simulating CPW path directly in Momentum. Otherwise, simulated data are different from measured data!! You can verify my assertion by designing a simple CPW line (using Strip and not Slot!) in Momentum and comparing it with an equal length CPW lumped element.

Did I make some mistakes in preparing the model? Is there anyone among you who has ever encountered this kind of problem?

thank you in advance!

Kaiserh

Joined: 03 Mar 2006
Posts: 14
Helped: 2
Location: Frankfurt/Oder, Germany

17 Jul 2008 17:00 momentum cpw

Hi sool83,

My question is why you use internal ports instead of single ports? Furthermore, as I remember it is not necessary to use two ports as "ground reference" for a CPW simulation. Generally, if you made the right set up for momentum the results are really close to ADS schematic simulation.

So just check the setup of your simulation (substrate, meshing and so on), then try with single ports only, then compare the results with schematic.

B.R.
Kai

asturias

Joined: 14 Mar 2008
Posts: 59
Helped: 5

18 Jul 2008 21:07 cpw simulation ads

Hi sool83,

I think that I can help you on CPW, I have already faced the same problem, actually it is a little bit difficult to do it in ADS, so send give me your email in order to send you some files. It is a little bit big and I can not upload it here.

jonnasi

Joined: 09 Mar 2008
Posts: 19
Helped: 1

08 Apr 2009 13:46 cpw ads

Hi,

did you solve your problem, because Im having the same problem? But i am simulating CPW with gnd plane.

What was the fault?

EM_fanatic

Joined: 06 Aug 2004
Posts: 6
Helped: 2

13 Apr 2009 14:23 cpw slot ads

You need to setup signal ports on the signal trace and ground referecne ports on the ground traces

skyeandgrass

Joined: 01 Jul 2009
Posts: 1
Location: china

02 Jul 2009 12:14 ads momentum simulate cpw

;;

h_bs_on_wafer

Joined: 25 Aug 2007
Posts: 2

11 Oct 2009 23:05 CPW Simulation in ADS

Could somebody upload and GCPW and/or CPW ADS model?

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besttor

Joined: 31 Mar 2009
Posts: 2

16 Oct 2009 7:34 CPW Simulation in ADS

I have done some work about simulating CPW lines in Momentum. I think for CPW simulation in momentum, Single Mode port with a Reference Offset maybe needed to get a more accurate result.

Be careful of the backvia, you may need to via properly as NOT to general unwant mode at the input port, or it could affect the calibration work. In Sonnet, the box are all grounded, but in momentum, you should ground the ground plan carefully first.