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TRF1208: TRF1208

ABM
Prodigy 10 points
Part Number: TRF1208

Hi. I've just downloaded the S-parameters file from the web page and , when simulating, there are stron resonances in several frequencies

Only RF ports for graph are added to S-parameter file, no other cmponents in circuit.

Any idea of the cause? Thanks!!!!

  • 0
    TI__Prodigy 620 points

    Hello ABM,

    Not sure what is causing the 'resonances' that you are seeing in gain parameters. The fact that no variation is observed in return-loss parameters at locations of resonances implies that it is not coming from the model, but a tool or setup artefact. You can try using a standard s-parameter analysis tool like Keysight ADS.

    Regards,

    -Anil

  • 0
    Prodigy 10 points

    Hello. I think that the problem is located in the S-parameters file. I've followed the steps:

    1.-Changing the interpolation method available in the AWR. The strong changes in results seem to indicate that it is not a real resonance, but a mathematical one. The 3 methdos are linear, rational and spline-8

    2.-Visual inspection of S-param file at the exact resonances shown in graph. A regular attern of changes is detected as follows

         a.-In 2nd row and 3rd row, first column, there is a change in sign exactly at frequencies in resonances

  • 0 in reply to ABM
    Prodigy 10 points

    b.-When these changes are reverted the result is the following graph:

    So, I suggets to verify the file or measure it new and, if possible, with higher number of points, Due to the great step in frequency even when these changes are made, there is some sensitivity to interpolation method when this is not flexible enough(high degree of approximation).

    Waiting for your comments and thanking your support in advance. Kind regards!!!!

  • 0 in reply to ABM
    TI__Prodigy 620 points

    Hello ABM,

    Thanks for the leads. There was indeed some problems with the model - s21, s31, s12, s13 values reversed their phase at some parts of the sweep. We are checking why this happened. Very likely it happened during board trace de-embedding step. Anyhow, I have fixed it and sending the corrected s3p file. We shall replace the file in ti.com with this new file. 

    The magnitudes of s21 and s31 should not have shown any problem since only phase got affected. ADS plot did not show any anomaly. I don't know why AWR shows it. Anyway with the new model, it should be alright with AWR also.

    Regards,

    -Anil

     TRF1208_3P3_T25_s_params_NEW.s3p