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  1. #1
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    Problem with diode linearizer for PA in MWO

    Hi

    I want to make a diode linearizer as a part of my PA. I use Microwave Office and have some problem: on the graph input sine wave is distorted, I use bias tee for biasing diods, so DC voltage can't influence on input circle. Have I to match linearizer with input and output 50 Ohm ports?
    Have anybody similar projects in MWO?

    Thank you.

    •   Alt25th March 2008, 12:02

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  2. #2
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    linearizer

    Hello alexandr22061986,


    Yes, you need to match the circuit...
    Upload your MWO project file (*.emp) so that we can comment on the same...


    ---manju---



    •   Alt8th April 2008, 06:02

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  3. #3
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    diode as linearizer

    Thank you for help, Manju.

    I have uploaded my file. Some problems I have eliminated. For control of nonlinearity level I change bias current of diods. How can I improve, increase control range of intermodulation garmonics level? Maybe I have to add a microstrip lines for phase shifting? And what type of diodes I need to use in MWO? ( PIN, physical model)?

    Thank you.



    •   Alt8th April 2008, 11:32

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  4. #4
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    Re: Diode linearizer

    Hello alexandr,

    This looks bit long description, but it is required to know about thw AWRDE environment...
    First of all it llooks you have not set the # of Harmonics option to required number...Just for verification once I modified to 9 it shows different spectrum results when compared to default 5 harmonics...so set the required relistic number...

    Second I have created new Input power In variable (Pin) to tune the input power level & see how exactly haronics in spectrum plot varies interactively...

    see the attached pictures & modified MWO project file for more details...


    Third I have created a new copy of the schematic & swept the power for using with VSS for system simulations & added additional input test point to check the input & output spectrum for QPSK modulation source...

    Regarding your other queries...
    Yes you need to use Microstripline models for actual phase shift or for simulation you can use phase shifter Ideal block...
    The Diode models usage in MWO depends on what Vendor device parameters available & corresponding matching/equivalent parameter diode model you need to use in MWO...
    for example for detailed accurate parasitic diode model you can use SDIODE (if all parameters available)...

    I hope this helps you...

    ---manju---


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