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LMH3401: 2GHz TIA application

Art Del Castillo
Intellectual 350 points
Part Number: LMH3401
Other Parts Discussed in Thread: LMH5401

To Whom it may concern:

 

Can the LMH3401 be used as  2GHz TIA with inputs from 4.5nA to 500nA?

Thanks

Art

  • 0
    TI__Genius 13935 points

    Hello Art,


    The LMH3401 has on chip Rf and Rg resistors, it cannot be configured as a TIA.  The LMH5401 is built on the same core and has no on chip gain set resistors.  I have configured the LMH5401 as a TIA with good success using a photo diode.  I get around 1GHz of bandwidth with the diode I  used.  The bandwidth of my circuit was limited by the diode capacitance.  You will need to have a very small amount of capacitance on the amplifier input to get 2GHz of bandwidth. 

    You will need to be able to extract your signal from the broadband noise.  Our current noise is 3.5pA/rtHz.  If you integrate this noise over 2GHz of bandwidth you get 157nA of current noise.  Depending on your signal spectrum you may be able to extract it from this noise.

    Regards,

    Loren



  • 0 in reply to Loren Siebert 1
    Intellectual 350 points
    Hi Loren!

    Thanks for you help.
    Please excuse my lack of knowledge, but do you happen to have a TINA simulation for the LMH5401 configured as TIA?
    Our photo diode capacitance is .65pF, and the output of the TIA needs to be between 5mV and 700mV prior to the ADC. I would like to simulate this prior to implementation.

    Thanks

    Art
  • 0 in reply to Art Del Castillo
    Intellectual 350 points

    LMH5401_TIA_3.TSCHi Loren!

     Can the LMH5401 configured as a TIA be able to work from a single 3.3V or 5V supply.  For some reason, my simulation does not work with single source supply (see attachment).

    Thanks

    Art