AD8054 settling time data


The AD8045 is a unity gain stable. Why the settling time data is only for G=2, and not for G=1?

I addition, why there are a lot of amplifiers  why the settling time data is only for 0.1% and not for 0.01%? 



  • 0
    •  Analog Employees 
    on Jul 14, 2020 7:38 AM


    I assume that you have a typo error in the title and referring to AD8045 as what the content is.

    It is true that the AD8045 is Unity Gain stable.
    Some characterization are done in different gains and these are specified.
    We had Gain of 1, 2, and 10 (Closed Loop Gain).

    For the Settling time, we had used the gain of 2.
    For the optimization of the part in respect to settling time, we are recommending to use gain of 2.

    For the Error Band of 0.1%, the AD8045 is a High Speed part.
    We usually use this error band for High Speed part(same with other high speed parts).
    Some Precision Op-Amps are using 0.1% and 0.01% and having 0.01% Error band will create more settling time.

    Please check also this link for additional information about Settling Time.

    Thanks and regards.

  • Thanks for your answe.

    Surly it AD8045. Anyway, if I understand your answer- The Hi-Speed amplifiers, which specified  to 0.1%, is not converge to 0.01% because some physical properties, like DI ? or am I wrong?

    I found some "old" part, as the AD8036, AD9631 and the diff-amp AD8138 which are specified for 0.01%. Can you recommended for updated amplifiers (less power, smaller package) with similar performances?


    thanks in advance



  • 0
    •  Analog Employees 
    on Jul 15, 2020 11:45 PM in reply to slmperl


    There are also some High Speed parts that specifies it Settling time at 0.01% error band but mostly at 0.1% only.

    May I know what are the other parameters you are considering from the AD8045?
    Basing from the AD8045, this part is low distortion, wide Bandwidth, high Slew Rate, fast Settling time.
    You have also mentioned you are looking for less power and smaller package.

    The part that seems to be closed to AD8045 parameters is the LTC622X series.
    Please check if this part fits your requirements in terms of Bandwidth, Distortion, SR, and Settling time.
    In addition, the part specifies its settling time at 0.01% error band.
    The LTC6228/9 has almost same power with AD8045 while the LTC6226/7 has less power however has lower Bandwidth and longer settling time.

    Also, you can use this link for Video Amplifier for checking parametric table Video Amplifier of the parts while here is the link for High Speed Op Amps.
    You can sort and filter whatever parameter you may want to look into.

    Hope this helps.

    Thanks and regards.

  • Hello.

    Thanks again.

    There are some parameters which is critical for my purpose:

    Input capacitance<1-2pF ; bias current < 20uA < Unity gain stable ; ultra low noise   ;settling time <20-30n to 0.01%( the less the better).BW>200M for 2Vpp output.

    Other parameters is preferred as  low power, small package(SOT 23 and smaller), single supply.

    I will check all your recommendations.