Port impedance in Layout, ADS

[moreho]

Hi.
I want to see if my 50 ohms track in the stripline configuration has how much impedance.
Maybe it needs to tune the width of that track.
I know I can theoretically use ads line calc.
But is anyway to get the port impedance from Layout EM Environment?
Thanks.

 

[volker@muehlhaus]

I think you want the line impedance, not port impedance?
Simulate a short length of line in 2-port (!) configuration. Then calculate Zline=sqrt(Z11/Y11).

In ADS data display:

Z=stoz(S)
Y=stoy(S)
Zline=sqrt(Z11/Y11)

That's it. Good luck.

 

[moreho]

Thanks so very much dear volker, that works good.
I test it for a three layer stripline.
I check the effect of line's length and see that the plotted impedance of line has very changing value over freq.
Also I check this way in the whole circuit and see a similar behaviour.

Clearly, this way is far from cst port mode information, that integrates all needed information of the port in one click in 1 window.

 

[volker@muehlhaus]

Thanks so very much dear volker, that works good.
I test it for a three layer stripline.
I check the effect of line's length and see that the plotted impedance of line has very changing value over freq.

Then you made a mistake (not grouped ports properly?) or the line was not short (length < 1/10 wavelength).

Also I check this way in the whole circuit and see a similar behaviour.

What do you expect as the Z0 of "the whole circuit"?
Obviously, line impedance is only defined for homogeneous line segments.

Clearly, this way is far from cst port mode information, that integrates all needed information of the port in one click in 1 window.

I know, other tools like Sonnet can also show the line impedance very easily. But you asked how to do it in Momentum, and I described a method that can give you the desired results - if used properly.

 

[moreho]

Then you made a mistake (not grouped ports properly?) or the line was not short (length < 1/10 wavelength).

i forget to say that bad effect was because of L>(for example)5Lambda. consider 100mm at 28GHz.
but for Small Length like 5mm it was Ok.

What do you expect as the Z0 of "the whole circuit"?
Obviously, line impedance is only defined for homogeneous line segments.

Consider CST, Port Mode Information. the information was calculated even the whole circuit is defined. it is not necessary to open a new cst workspace and draw a line for imp. calculation.
i only want to make a comparation dear volker.

I know, other tools like Sonnet can also show the line impedance very easily. But you asked how to do it in Momentum, and I described a method that can give you the desired results - if used properly.

thanks in advance volker.

 

[volker@muehlhaus]

Consider CST, Port Mode Information. the information was calculated even the whole circuit is defined. it is not necessary to open a new cst workspace and draw a line for imp. calculation.

I see ... and agree, as far as wave ports are concerned.
That is what Sonnet also does, as a side results from port calibration.

Just for completeness: ADS Momentum also has a port mode solver option, but only for thin metal (sheet), and I don't know how to get (plot) that port impedance. For ADS FEM, I am not sure ... you should be able to get the wave port impedance, similar to CST port mode solver.