power source with complex port impedance

  • Anonymous - 2012-06-06

    i would like to have a complex port impedance on a power source, but when i simulate this i get an error,

    line 4: syntax error, unexpected COMPLEX, expecting '"'
  •  magneto98

    magneto98 - 2012-06-06

    Mathematical operations inside component properties don't work. (e.g. 3+5*j)
    Assign your complex value to a variable and assign the variable name to the component property. (Tested)

  • Seb

    Seb - 2015-03-26


    Did that (in attachment) but not seems to work. Is that the way you did it magneto98?
    The simulator see only 50ohm, and not the imaginary part.

    Thank you.

  • Claudio Girardi

    Claudio Girardi - 2015-03-26

    just checked the source code and indeed the source port impedance can only be a real number... don't know why magneto98 assumed that it can be complex...

  • Seb

    Seb - 2015-03-27

    Thank you for your help Claudio. Have you got an idea of how to do it? Maybe a 1-port S-parameter file could do the job?

    I'm trying to match a transistor output to 50ohm at 1GHz, that's why a complex port impedance would be useful.

    Last edit: Seb 2015-03-27
  • Claudio Girardi

    Claudio Girardi - 2015-03-27

    If I understood correctly, you would like to enter an arbitrary complex impedance and then design the appropriate matching network. If you have the S-parameters of the device, you can use the "2-port S-parameters file" component; you can also create the file by yourself, it is a simple text file, format defined here http://www.vhdl.org/ibis/connector/touchstone_spec11.pdf .
    If you would like just a frequency-independent impedance you can use an "equation defined 2-port RF device" component; just define the Type of parameters you would like to define (e.g. Z), connect only port 1 and then define the corresponding parameter P11 with the desired complex impedance (e.g. 50+j20).
    Note that, after simulating the circuit, you put a marker on a graph representing S[1,1], right clicking on it will allow to select "power matching", which will open the matching tool to automatically design the appropriate matching network for a specified target impedance and frequency.

  • Seb

    Seb - 2015-03-27

    Exactly what I needed, I'll try next week with the 1-port S parameter file, doesn't seem too hard to write!


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