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OPA659: Unity gain bandwidth

Bart Klusek
Prodigy 200 points
Part Number: OPA659

Hi,

The datasheet for OPA659 states, on the first page, that the unity gain bandwidth of the opamp is 650 MHz. Then, on page 3, OPA659 is listed as a "related part" (!) with a bandwidth of 350MHz.

Also, the label of the bag of samples I received from TI (thanks!) says  "IC OPAMP JFET 350MHZ".

So, which number is correct? I presume it's 650MHz, but would like to be sure.

Thanks!

Bart

  • 0
    TI__Genius 15975 points

    Hi Bart,

    It is true that the small signal unity gain bandwidth of OPA659 is 650MHz.

    However, it is the gain bandwidth product (GBP) that is specified at 350MHz. In the datasheet, the GBP is usually calculated based off the -3dB BW measured at higher gains (>10), so that there is no peaking in the frequency response. If you look at Figure 1 and 2 in the datasheet, it is actually the 2dB peaking that gets around 650MHz BW at unity gain (where the phase shift is close to 45'). For higher gain settings, it should more or less track the GBP of 350MHz.

    Best Regards,

    Rohit

  • 0 in reply to Rohit Bhat
    Prodigy 200 points
    Got it. Thanks!
    B.