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Superheterodyne receiver

  1. Dec 7, 2012 #1
    1. The problem statement, all variables and given/known data
    super heterodyne receiver made up of a LNA a mixer and an IF respectively.

    LNA
    NF1=?
    G1=?

    MIXER
    NF2=2.5DB
    G2=-3.5DB

    IF AMPLIFIER
    NF3=28DB
    G3=7DB

    THE OVERALL NF OF THE RECEIVER SHUD NOT EXCEED 6.5DB AND THE OVERALL GAIN SHOULD NOT EXCEED 32DB


    2. Relevant equations

    FRIIS EQUATION

    NR=NR1 + NR2-1/G1 + NR3-1/G1.G2

    3. The attempt at a solution

    NR2=2.24
    G2=0.446
    NR3=5.011
    G3=630.96

    GTOT=32=G1+28-3.5=7.5DB
    G1=5.62

    NF OF SYSTEM =6.5DB=4.467

    USING FRIIS
    2.647=NR1
    therefore NF1=4.23dB

    Am I working out the gain and the NF of the LNA correctly? or is there other bits of info I should need/be using
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
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