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nport Issue

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I am simulating n4port element in spectre. My s-parameter file is in spectre format. I am using linear Interpolation. For my setup, I have a AC source connected to port 1+ as my input. I am doing AC frequency analysis and observing output at other 3 ports. I do not get any output on ports 2, 3 and 4. I see the entire signal on port 1-. Can you tell what my problem could be?

Let me know if you need anymore information.

Chintan Shah
chshah@ncsu.edu


Originally posted in cdnusers.org by shahch31

  • This is almost certainly because you've not terminated the nport with sensible impedances. The s-parameters were probably measured assuming 50-ohm (or something similar) ports - you can see this by looking in the s-parameter file.

    If you connect an ac vsource directly to an nport pin, it's going to do all sorts of horrid and unrealistic things.

    I just tried doing it, and I got similar results to what you describe, so I'm assuming you've just connected the circuit up inappropriately.

    Regards,

    Andrew.


    Originally posted in cdnusers.org by adbeckett

  • I figured out what my problem was. I needed to ground the negative terminal and on the positive terminal connect a pdc source on all 4 ports which would allow me to run a s-parameter simulation. I was not successful with running transient but I am assuming you won't be able to run transient for a nport element. Thank you for looking into this problem.

    Thanks,
    Chintan


    Originally posted in cdnusers.org by shahch31

  • I also got the transient simulation working. I forgot to include the model file. I connected a 50 Ohm resistor at the input and all the outputs. Thanks again for your help.

    Thanks,
    Chintan


    Originally posted in cdnusers.org by shahch31

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