problem when i made simulation momentum in ADS

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khaldoon99

Joined: 13 Dec 2005
Posts: 37
Location: Belguim

06 Nov 2009 17:58 problem when i made simulation momentum in ADS

Hi all,

I have a project of design Amplifier at 4 GHz in ADS and when i made DC_BLOCK I had a good result for S11&S12 but when i simulate it by Momentum i had a bad result, so i don't know where is the problem.

you can see my numbers.
thx

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tomtomson

Joined: 11 Apr 2008
Posts: 11
Helped: 2
Location: California

06 Nov 2009 22:50 problem when i made simulation momentum in ADS

Judging by the picture of the schematic, it doesn't seem like you've used the MSTEP block under TLines-Microstrip.

Your conductor goes from width, 'w' to width, 'wc' and this difference in width creates some more parasitic capacitance that isn't realized in the regular ADS simulation. You need to include thes MSTEP at every junction that there is a change in conductor widths and adjust your lengths accordingly to get your desired response.

As a first level of troubleshooting, I think this will match up your ADS simulation with your momentum simulation. Hope that works.

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khaldoon99

Joined: 13 Dec 2005
Posts: 37
Location: Belguim

07 Nov 2009 0:59 Re: problem when i made simulation momentum in ADS

thank you for your advice but that doesn't solve the probleme.
In fact, i have good result befor making momentum and you can notice that my first figure at 4GHz is perfect and in the momentum it will be good at 3GHz.

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tomtomson

Joined: 11 Apr 2008
Posts: 11
Helped: 2
Location: California

07 Nov 2009 1:54 problem when i made simulation momentum in ADS

I went ahead and setup your schematic as shown in the first jpg and simulated it in ADS and momentum by just importing it directly to the layout and setting up momentum and then running momentum. My ADS simulation matches yours. However, my momentum simulation is in line with my ads simulation, not what your momentum simulation looks like.

So it must be how you setup your momentum simulation. What are the steps you take to set up your momentum? It might be easier for you to post your project folder and I may be able to go through it...

khaldoon99

Joined: 13 Dec 2005
Posts: 37
Location: Belguim

07 Nov 2009 2:10 Re: problem when i made simulation momentum in ADS

I posted my project in this link:

http://www.edaboard.com/ftopic368109.html
Please just take the final file(.PDF), so also i share you your opinion about my parameter of momentum but i put it by defult and i take Momentum (without RF Mode) - simulation - s-parameters-simulate
Sweep mode:adaptive
sample point limit: 15

At any cases, please can you attach the picture of your simulation of momentum.

thx for your time.

tomtomson

Joined: 11 Apr 2008
Posts: 11
Helped: 2
Location: California

07 Nov 2009 4:48 problem when i made simulation momentum in ADS

I'm confussed on what you did in Momentum. Did you define your substrate, set it up, and then define and set up the mesh before you simulated your s-parameters?