ADS_momentum simulation impedance matching issue

I want to match 50 to (0.7-j*1.9) using micro strip lines.
I used ADS momentum to match the impedance for 880mhz to 915mhz. The layout and results are shown in attached files. After this schematic was updated from the momentum layout. But the results are different. Is there any thing which i missed?

Hi

You have a capacitor in your schematic, this is not present in the layout?

Regards

i have no idea how to use and tune lumped components in momentum.

Have a look at this post

https://www.edaboard.com/threads/176064/

Usually you place a internal port where you need the lumped element. Then you simulate in Momentum and make a Layout-component in schematic. Now you can attach the lumped component.

what is the impedance of internal port.

how can i import layout-component in schematic

---------- Post added at 12:41 ---------- Previous post was at 12:17 ----------

in the schematic there is 24pf capacitor. so i calculated its impedance at 900mhz which is -7 ohm .and assigned it to the internal port. is it ok?

Well this would properly work at 900 MHz. But at lower frequencies the reactance would be higher and a lower reactance at higher frequencies. This will give a wrong result.

I am still confused about the method i followed.

Consider the discontinuities in the schematic and a short transmission line, use a t-junction to model the discontinuity in schematic, and use a capacitor model from any of the libraries.
Also u can generate ur schematic from layout except the capacitor.

tyassin said:

Usually you place a internal port where you need the lumped element. Then you simulate in Momentum and make a Layout-component in schematic. Now you can attach the lumped component.

Click to expand...

From Layout, go to Momentum, Component, Create (something like that... not at my PC with ADS on it, at the moment). A window will pop up with simulation parameters, plug in the default values that you intend to use (Low freq, High freq, Edge mesh, etc). When you click OK, ADS will create a "Look-a-like" component. Go to a blank schematic, open the component browser, look under your _prj folder, and there should be a new component with the name of your layout file. Drag-drop it onto the schematic.

Once you have the look-alike on your schematic, wire it up like any other part (hook up the cap to the little dot in the middle for P3, and hook up two Terms for P1 and P2, assign their impedance's accordingly, so you can run an S-Param sweep). When you click Simulate, ADS will "push into" the look-alike part, run a Momentum simulation to calculate it's S-parameters, then feed that information back to the schematic. Then the schematic will run an S-Parameters sweep (or transient, or Harmonic Balance, etc) using the recently-calculated S-parameters for the Momentum look-alike object.

One recommendation, depending on how big the cap is, you might want to move port 3 so that it's close to an edge of the matching network, so you could set one of the terminals of the cap on the point for P3, and the other terminal would not be laying on the RF network, but would sit on some nearby ground metal. I'd suggest making your middle MLIN into an MTEE, then connect P3 to the pin at the "edge" of the matching structure.