GBW spec for TIAs

Discussion in 'Electronics Resources' started by vuhong, Mar 6, 2012.

  1. vuhong

    Thread Starter New Member

    Mar 6, 2012
    Hi there,

    I've been looking all around the internet for an answer to this question but can't seem to find a clear one...

    I'm trying to select op-amps for a project and one important spec if the gain bandwidth product (GBW). The normal calculation is pretty easy (using voltage-to-voltage gain), but how would I spec it for a transimpedance gain, since the gain is in dB-Ω.

    For example an OPA656 has a GBW of 230MHz, what would that equate to in terms of a transimpedance GBW?

  2. steveb

    Senior Member

    Jul 3, 2008
    When you have these types of doubts, it is best to just derive the equations using the nonideal opamp model. If memory serves me, the transfer function rolls off at the gain bandwidth frequency, similar to a voltage amp with unity gain.