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ONET2591TA: ONET2591TA input referred noise

Patrick Lepage
Prodigy 50 points

Part Number: ONET2591TA

Hi.  I intend to use the ONET2591TA for an application that requires 700MHz bandwidth.  The Input referred RMS noise is specified only at the full bandwidth of 2.5 GHz.  Do you have data of Input referred RMS noise vs frequency ?  And do you have this data for capacitance values other than 0.6pF ?

Thanks,

Patrick Lepage

  • 0
    TI__Mastermind 22684 points

    Hello Patrick,

    Those are good questions.  For this device the dataset present should be accurate for the device's operating range.  As it were, the data and tables specified in the datasheet do represent the behavior of the device across its frequency range, including your 700MHz use.  The same is true for your question regarding differing capacitance values from the stated 0.6pF.  I would proceed with the existing data as your guide; if you get performance vastly different than what is promised I would reconnect with those specific details.

    If you do run into any simulation issues or have further questions, my team and I would be happy to assist you with those.  I cannot provide any additional data outside of what is present on the datasheet; this IC is fairly old so additional test data is not as readily accessible.

    I do hope this helps you move forward.  Please do respond about further issues or any other questions.  

    Best,

    Alec

  • 0 in reply to Alec Saebeler
    Prodigy 50 points

    Thank you Alec.

    I assume the Input referred noise current density is not constant with frequency.  Since the input is connected to a capacitance the noise density should be higher at higher frequency.  Is this assumption correct ?  

    Patrick Lepage

  • 0 in reply to Patrick Lepage
    TI__Mastermind 22684 points

    Hi Patrick,

    Great question: the integrated input referred RMS noise is constant as it is integrated over the bandwidth of the IC. That will be independent of frequency. However, the current input “spot” noise (amps/rtHz) is likely to increase a bit at higher frequencies. 

    Best,

    Alec

  • 0 in reply to Alec Saebeler
    Prodigy 50 points

    Thanks Alec,

    One more question.  Are there eval boards for the ONET2591 or other TIAs of the ONET family ?  Any Spice models ?

    Patrick Lepage

  • 0 in reply to Patrick Lepage
    TI__Mastermind 22684 points

    Patrick,

    I am sorry to report there is not a SPICE model available for the ONET2591 or other members of the ONET TIA family.  I also cannot find any reasonably recent evaluation boards for these products.  There used to be a ONET-10G-EVM which worked for several ONET ICs, but it is not supported any longer.  It may also not have worked with the ONET2591 even if it was still in production.

    Best,

    Alec