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TRF371135: Gain Clarification and Noise Figure Model

Ben Siegel
Prodigy 20 points
Part Number: TRF371135

I am confused as to what the typical gain is for this. In the datasheets I see graphs relating the gain to the LO and not RF, which seems a bit odd to me, with gain around 40 dB. Is using the LO reference for the gain the proper way to go about it? Also could you tell me what noise model is used for the noise figure?

  • 0
    TI__Intellectual 2245 points

    Hello Ben,

    The TRF371135 has an integrated baseband PGA that provides 24dB of gain range, in 1-dB steps.

    Figure 45 of the datasheets provides the gain of the device in relation to the PGA gain setting. This data is characterized with the LO power kept at 0-dBm.

    As for the noise model, we use the Y-Factor method.

    Regards,

    -Oscar

  • 0 in reply to Oscar Guevara
    Prodigy 20 points

    Thank you for the help.

    So if I understand Figure 45 correctly, with the 3 dB attenuator off, the gain range is between about 17 to 40 dB, and this is in reference to the LO power input which is taken to be 0dBm.
    Do you know if Figure 45 is LO frequency invariant? For instance, can I apply this to how gain changes over different LO frequencies as shown by Figure 4 to calculate gain at settings other than +24dB?

    Also, in regards to the noise figure vs LO frequency data, to which output port do Figures 5 through 7 refer, the BBIout, BBQout or some other output? Is there any data on how the noise figure depends on RF input?

    -Ben

  • 0 in reply to Ben Siegel
    TI__Intellectual 2245 points

    Hello Ben,

    Your understanding is correct. Also yes, you can use the gain variations from figure 4 to estimate the gain at different PGA gain settings over different frequencies.

    The Noise figure data from Figures 5-7 can refer to either BB outputs. Lastly, the Noise figure is independent of the RF input as long as the device is not being overdriven.

    Regards,

    -Oscar