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  1. #1
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    Which transistor would best suit for 8.3 - 8.7 GHz X-Band LNA design?

    Could someone tell me which Transistor would best suit for 8.3 - 8.7 GHz ? and also a design approach to meet the requirements.
    Gain: 45dB
    Gain Stability: 0.5dB
    Output Impedance 50 ohms
    I/O VSWR: < 1.3
    DC Power: 12V

    Any related documents to obtain the same would be of great help. I would be using Ansoft Designer and CST. Please comment on the same.

    How many stages of LNA would be required to obtain the target Gain ? and also what Bandpass Filter (my choice is hairpin filter as of now) will be best suited ?

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  2. #2
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    low noise amplifier design

    To get 45dB of gain at this frequency from one transistor is impossible. You need at least 3 stages.
    Try GaAs FETs from AVAGO:

    http://www.avagotech.com/pages/en/rf...effect/ephemt/

    Hairpin Filter at this frequency and bandwidth should be fine.



  3. #3
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    x-band lna stability

    You can try Eudyna's FHX13x



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    lna design using ansoft designer

    Try BFR949f



  5. #5
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    x-band

    Quote Originally Posted by vedagarbhamsandeep
    Could someone tell me which Transistor would best suit for 8.3 - 8.7 GHz ? and also a design approach to meet the requirements.
    Gain: 45dB
    Gain Stability: 0.5dB
    Output Impedance 50 ohms
    I/O VSWR: < 1.3
    DC Power: 12V

    Any related documents to obtain the same would be of great help. I would be using Ansoft Designer and CST. Please comment on the same.

    How many stages of LNA would be required to obtain the target Gain ? and also what Bandpass Filter (my choice is hairpin filter as of now) will be best suited ?
    To get so much gain at this frequency you need a multi stage amplifier. You mention that this is an LNA but there is no indication about the NF of the amplifier you need to construct. What is its use? A very low noise can be accomplished by the MGF4919G and the NE3210S01 as can be seen in the gk-electronics.gr website, but they are expensive.
    I would say these are among the best transistors as far as concern NF in these frequencies.
    Note: NF is defined almost totally by the first stage of your amplifier, i.e. the first transistor, so you probably only need 1 of these.
    The rest can be higher noise ones without affecting the performance of the LNA too much. See here for a calculator: http://www.microwave.gr/content/casc...l_nf_calc.html



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  6. #6
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    lna design in edaboard

    hello everyone
    i am a ug student and doing a project on low noise amp
    i want the basic tutorial + design circuit for the same.




    thanx



  7. #7
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    low noise amplifier x-band

    An LNA is no different than a preamplifier. So any small signal amplifier/preamplifier tutorial will be fine for you. The only thing with LNAs is that the first stage needs to use a low noise active device (transistor), so you have to look for a low noise transistor/MMIC for the frequency you want.
    And you need to define what low noise means to you. If 3db total NF can be defined as a low noise amplifier by your project supervisor, then you can just use an MMIC at lower microwaves. See www.gk-electronics.gr for short data and samples on some MMICs.
    Noise figures of <1db are more difficult and expensive to achieve.



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