1 Reply Latest reply on Aug 12, 2011 12:22 AM by david.ron

    Transimpedance Amplifier Cutoff Frequency

    anish.bhide

      Hi,

         

      I was curious as to how the -3 dB Frequency was calculated for the transimpedance amplifier. The Data sheet says that this is calculated based on

         

      f -3dB = 1/ (2*pi* Rfb* Cfb)

         

      Which is not actually the case for the autocalculated value in the TIA configuration menu.

         

      for example, with:

         

      Rfb = 20k

         

      Cfb = 4.6 pF,

         

      the cutoff frequency should be about 1 729 945.03 Hz ? but the autocalculated value is 866 kHz...

         

      perhaps someone can shed some light on this?

         

      Thanks!

        • 1. Re: Transimpedance Amplifier Cutoff Frequency
          david.ron

          From what I observe, the calculation of bandwidth of TIA is dependent not only on the feedback resistor and feedback capacitor, but also on the power setting selected.

             

           

             

          The bandwidth is definitely inversely proportional to the product of resistor and capacitor. But if the power mode is set to "High Power", then the Bandwidth is higher. But if the power setting is set to "Minimum Power", then the Bandwidth is miniumum.