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  1. #1
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    converting s11 to impedance

    Dear all.
    I'm a new comer, i wish to learn alot from you.
    I have designed a PA module using BLF278. but datasheet only give me S11,S12.S21.S22 and I need convert to Zin and Zout in complex impedance. (or how to use S-paramter)
    Please help me
    Thanks

    •   Alt16th February 2009, 14:55

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    s11 impedance

    Z = (1 + ρ)/(1-ρ)

    ρ = (Z-Z0)/(Z+Z0)

    Z0 is usually 50 ohms. These calculations are, of course, complex.



    •   Alt16th February 2009, 16:15

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    s11 to impedance

    You can use the calculations from the link
    http://www.rfcafe.com/references/electrical/s-h-y-z.htm



    •   Alt18th February 2009, 13:17

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  4. #4
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    convert s11 to impedance

    Thanks you very much for so many helps.
    But BLF278 only give me S11 and Φ; (see table). I must convert to Zs and Zl in complex impedance.
    Thanks.



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    s11 convert s22

    Maybe I wasn't clear enough.

    Zin = 50*(1 + S11)/(1 - S11)

    And

    Zout = 50*(1 + S22)/(1 - S22)

    where Zin and Zout are the impedances looking INTO the device. You have to mutiply by 50 to convert the normalized impedance into ohms (assuming your S parameters were measured on a 50 ohm network analyzer).

    The table you published has S11 as mag[s11] and ang[s11] for various frequencies. These are complex numbers. You do the complex division, one frequency at a time, and the answer is also a complex quantity, either in magnitude and angle, or Real and Imaginary parts, depending on how you choose to do the arithmetic.


    Rich
    www.MaguffinMicrowave.com



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    s11 conversion to impedance

    See below:



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    s11 to complex impedance

    thanks alot



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