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    How to define DC Gain of Operational Amplifier or OTA ?

    Hi,

    I have very basic question in mind. How do we decide DC Gain of OPAMP or OTA irrespective of application ? Does it decide on basis of settling error voltage or it has some other relation.

    If you have any good and basic refernce for it. then, please share it.

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    Re: How to define DC Gain of Operational Amplifier or OTA ?

    How to define DC Gain
    How do we decide DC Gain


    What do you mean?
    Are you going to design an amplifier?
    Or do you ask for measurement techniques?



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    Re: How to define DC Gain of Operational Amplifier or OTA ?



    DC gain is determined by feedback ratio Rf/Rin for inverting and for non-inverting input DC gain = { 1+ Rf/Rin }ratio

    Details
    http://en.wikipedia.org/wiki/Operational_amplifier
    A good design question lists your overall requirements™ The best question deserves a better answer. ™
    ... Tony Stewart EE since 1975



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    Re: How to define DC Gain of Operational Amplifier or OTA ?

    Hi LvW,

    My question is What are factor we consider while deciding Gain as specifications ? Does Settling Error has relation with it ? then how ?

    - - - Updated - - -

    Hi LvW,

    My question is What are factor we consider while deciding Gain as specifications ? Does Settling Error has relation with it ? then how ?

    - - - Updated - - -

    Hi LvW,

    My question is What are factor we consider while deciding Gain as specifications ? Does Settling Error has relation with it ? then how ?



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    Re: How to define DC Gain of Operational Amplifier or OTA ?

    The desired gain is determined by the application. For example if you have a 0-100mV peak signal from a sensor that you want to expand to the 0-5V range of an A/D converter than you need a gain of 5/0.1 = 50.

    The settling time can be affected by the gain. You have to look at the gain-bandwidth and settling time specs for the particular op amp you are using to determine what that is.

    Edit: Deleted double post.
    Last edited by crutschow; 22nd July 2012 at 16:44.
    Zapper
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    Re: How to define DC Gain of Operational Amplifier or OTA ?

    You have already answered your own question.
    The main consideration is the error that you will see at the output when non-ideal circuits are used.
    This error has various components
    1. Input common-mode variation
    2. Input-referred offset
    3. Gain error, which is derived from feedback network accuracy and opamp open loop gain



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