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TRF371125 RF Balun

Other Parts Discussed in Thread: TRF371125

The suggested RF baluns for the TRF371125 are 1:1 (50-ohm/50-ohm). I'm operating at 3 GHz  and there doesn't seem to be much of a selection available with good amplitude and phase balance. I have found some 1:2 baluns with better performance. Would it be okay to use a 1:2 balun and feed the RF input with 100-ohm differential instead of 50-ohm?

Does anyone know what is the differential input impedance of the MIXinp/MIXinn port at 3 GHz?

John

  • John:

    I have found that many of the baluns that are rated for common telecom or WiFi bands can be extended in frequency with good performance. For 3 GHz, you can check out the following parts:

    - Anaren BD2326L5050A00
    - Johanson 2500BL14M050
    - Murata LDB212G4005C

    It looks like the performance of these devices is still good at 3 GHz. Phase balance is getting on the edge, around 5 degrees imbalance, which may be undesirable.

    If there is a better 2:1 balun available, specifically with better phase imbalance, then it should be good to use. I have previously tested with 2:1 baluns and do not recall any ill effects. The actual (simulated) differential impedance is closer to 70 ohms so really there is some mismatch whichever way you go.

    --RJH
  • Thanks.

    It sounds to me like a 1.5:1 (75/50) balun would be optimal to match with the ~ 70 ohm differential input.

    I'll see if one is available at 3 GHz.

    John