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High Frequency Opamp

Dilip Kumar Venkatesh
Prodigy 30 points
Other Parts Discussed in Thread: THS4304, OPA847, THS4302

Hello,

I am working on a project which needs a standard opamp (with an inverting and non-inveritng input terminal and single ended output)  which can go up to frequency, greater than 900Mhz with a Gain bandwidth of in the ‘GHz’ range. Right now the most important parameter is the frequency. Kindly let me know if TI has the Opamps which I am in need for.  


Thank you

  • 0
    TI__Genius 12631 points

    Hello,

    The THS4304 is one of our fastest amplifiers. The OPA847 is another choice. In any case here is a link to a list of TI high-speed opamps. You can use the filters to the left to further narrow your selections. I would suggest using the filter to only select

    Bipolar, CMOS, FET Current FB and Voltage FB.

    Once you do that you can click on the BW @ ACL column to sort the selections by bandwidth.

    Samir

  • 0
    Prodigy 30 points
    Hi Samir,

    Thank you for the suggestion. However I have a question, the OPA847 says that the GBW=3.9Ghz and for THS4304 GBW = 3Ghz but the frequency response graphs shows better performance for THS4304 as opposed to OPA847 (Comparing the first frequency response in each Opamp ), is there a reason for this? and also is it better to look at the small signal response or large signal response for mu application of getting a good gain at 900MHz.

    Thank you
  • 0 in reply to Dilip Kumar Venkatesh
    TI__Genius 12631 points
    Dilip,
    The OPA847 is what is known as a decompensated amplifier, which means it is not unity gain stable. The lowest gain it is stable at is 12V/V. So for example in a gain of 12, the closed-loop bandwidth is 3.9GHz/12 = 325MHz....which in retrospect doesn't meet your 900 MHz need. Sorry for my oversight.
    Looks like the THS4304 is your best bet with regards to achieving 900 MHz. Note however that this is small signal BW. For a 1Vpp signal the THS4304 can achieve a bandwidth of only 450 MHz.

    If you want 900 MHz of small and large signal bandwidth then the THS4302 which is a fixed gain of 5V/V amplifier will meet your needs. What gain configuration do you need?