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  1. #1
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    Questions about the definition of Z-matrix and Zin and Zout

    Dear,

    I use ADS. I am quiet puzzling about the definition of Z-matrix and Zin and Zout.
    Question:
    In ADS, I use stoz(S) to get the Z-matrix of the network.
    In schematic, I write the following measurement equations to get Zin and Zout.
    Ztmp = stoz(S, 50)
    RinEVB = real(Ztmp(1,1))*50
    XinEVB = real(Ztmp(1,1))*50
    RoutEVB = real(Ztmp(1,1))
    XoutEVB = real(Ztmp(1,1))
    Also, I use another way to get Zin and Zout:
    Zin1 = sm_z1(S, 50)
    Zout2 = sm_z2(S, 50)
    As expected, RinEVB roughly equals Zin1 and RoutEVB roughly equals Zout2.
    While there are some difference between the 2 approach. My question is, which way is more accurate.
    Also, I found that XinEVB and XoutEVB differs a lot from imagines of Zin1 and Zout2. What is the reason, and which on is correct?

    Thank you.
    Jade

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  2. #2
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    Re: Questions about the definition of Z-matrix and Zin and Zout

    You confuse z-parameters and Input/Output Impedances of a 2-port.
    z-parameters are "open circuit parameters" and z11 is not equal to Zin ( or z22 is not equal to Zout )
    Pay attention to definitions.. z11=v1/i1 while i2=0 !! similarly z22=v2/i2 while i1=0..
    Zin is a measure of 2-port while 2nd port is terminated by Zo.. This is important.


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