Comparison of TIA gain and Gain Bandwidth Product


i am designing a TIA for the photodiode and using LTC6078 opamp . However i need a very large gain 100Meg Ohm and gain bandwidth product of LTC 6078 is 750kHz. So the theoretical bandwidth of the circuit  (calculated from GBW product) is 750 000 / 100 000 000 = 0.0075 Hz... I think i have done something wrong in the calculation or interpreted the gain of TIA incorrectly. 

Could anyone suggest where I have gone wrong?

Thank you.

  • 0
    •  Analog Employees 
    on Jun 29, 2020 2:20 AM


    If you can check LTC6268/9 DS which is at this link, you can review application information which is at pages 13 to 14.

    One of the discussions is about the achievable bandwidth of the TIA which is:

    Achieving Higher Bandwidth with Higher Gain is also discussed on the application information.

    Hope this helps.

    Thanks and regards.