LT1997-3 Rn、Rp Calculation

Hello

I tried to make a circuit equation like the attached file because I didn't know what to put as Rp, Rn to verify the formula of note 9 in the data sheet.

Vos,out=(Vos x NOSEGAIN) + Ios x 22.5K + Ib x 22.5K x (1 - Rp/Rn)

However, the above formula cannot be derived.
When I looked up and searched, the attached formula
Ios = Ib +-Ib-
Ib = (Ib + + Ib-) / 2
Can you help me because I can't derive the above formula?


Thank you.

PDF

Parents
  • Hi Osamu,

    You inspired me so much with your math that I decided to try my hand at it. Equations not show in this window and you should download file. Please, look at my results:

    PDF

    In other words, Rp and Rn is conductance at inv. and non-inv. inputs of internal op-amp. Usually, differential amplifier has internal resistors networks which cannot be change but LT1997 gives the user a choice of resistors.

    But I can be wrong...

    Regards,

    Kirill

Reply
  • Hi Osamu,

    You inspired me so much with your math that I decided to try my hand at it. Equations not show in this window and you should download file. Please, look at my results:

    PDF

    In other words, Rp and Rn is conductance at inv. and non-inv. inputs of internal op-amp. Usually, differential amplifier has internal resistors networks which cannot be change but LT1997 gives the user a choice of resistors.

    But I can be wrong...

    Regards,

    Kirill

Children
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