op amp questionsHi

Discussion in 'Homework Help' started by Kayne, Aug 21, 2011.

  1. Kayne

    Thread Starter Active Member

    Mar 19, 2009
    105
    0
    Hi,

    I wanted to check some answers for the question that are in the attachement. There are 3 question A,B,C which answers are povided below

    A.

    Temp change of 24dC
    Temp coefficient of input offset = 15uV/dC

     24*15*10^{-6} = 0.36V

     gain = \frac{2.2*10^6+10*10^{3}}{10*10^{3}} = 221

    221 *2*10^{-{3}} = 0.442

    So the variation is

     0.442 - 0.36 = 0.082V

    B.
    input offset voltage = 0.69mV

     voltage gain =\frac{ 1*10^6+10*10^{6}}{10*10^{6}} = 101

    error voltage at output

     101*0.69*10^{-3}= 0.06969V

    so the error voltage at the output is 0.06969V

    C.

    Amp gain = 668
    Resistor = 32k
    input offset current = 7.3nA

     Vin = IR = 7.3*10^{-9} * 32*10^{3}= 0.0002336V

    So the error voltage at the output is

     Voutput = gain * Vin = 668* 0.0002336 = 0.156044V

    So the error voltage at the output is 156mV

    Thanks for your time and help
    Kayne
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    1. question:

    gain is 220. Rfeedback/Rin. gives you a variation of 79.2mV
     
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