Slew Rate

Discussion in 'Homework Help' started by ac_dc_1, Jan 30, 2013.

  1. ac_dc_1

    Thread Starter Member

    Jan 27, 2013
    74
    0
    I have the following problem:


    Consider that the product between the gain-bandwith of an OpAmp is 1Mhz.Design a circuit that has a 34dB with a bandithw of 50 khz..

    I have no idea how to solve this.The gain in dB is given by 20*log(Vout)/(Vin)=34dB...How can i determine Vin with the data given?
    <br />
<br />
w*Vomax=SR<br />
<br />
2*pi*fomax*vomax=SR<br />
<br />
fomax=SR/(2*pi*vomax)<br />
<br />
    Question 2)If an OpAmp has a diferential gain Ad=10^4 and a comon gain Ac=10^-1 and a error of about 10% when the output tension is 2.5V

    Determine Vc and Vd in the input (Comon voltage and diferential voltage)

    So i know that  Vo=Ad(Vp-Vn)-Ac((Vp-Vn)/2)

    I believe i need another equation in order two find the two variables Vc and Vd

    The info that the error is 10% when Vin=2.5 V does that tell me that Vp-Vn=0.10


    Question 3)Consider an OpAmp with SR=4V/micro second

    Calculate the maximum frequency that a 5v sinusoide may have in order to be amplified without SR distortion

    *<br />
<br />
w*vomáx=SR<br />
2pi*f*5=4*10^6<br />
 <br />
f=127,3385 kHZ<br />
<br />
 f<=127,3385 kHZ <br />

    is that it?
    Thanks


    Question 4) If we increase the resistor in a integrator circuit what happens(the resistor of RC constant)

    I believe that the frequency of integration increases..And what else?


    Question 5) What happens if we increase the resistor R(not the feedback resistor the other) in a hysteresis comparator that is whose output is conected to the capacitor of a integrating circuit?It increseases the integrating period?

    Thanks
     
    Last edited: Jan 31, 2013
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    <br />
34dB= 20 \cdot log \frac{V_out}{V_in}<br />

    Re-arranging:

    <br />
V_out = V_in \cdot 10^{\frac{34}{20}} <br />
    Assuming V_in = 1V

    <br />
V_out = 50.11872V  <br />

    Therefore, the Voltage gain is about 50.12.

    Checking our work...
    <br />
dB=20 \cdot log(\frac{50.11872}{1})<br />
dB = 34dB<br />

    The rest of your post is simply math, though you left units out, and did not format it very well, making it difficult to understand quickly.
     
  3. ac_dc_1

    Thread Starter Member

    Jan 27, 2013
    74
    0

    Ok what about question 2 and 3?Any ideas??

    Thanks
     
    Last edited: Feb 1, 2013
  4. ac_dc_1

    Thread Starter Member

    Jan 27, 2013
    74
    0
    What about question 3 is that rigth?
     
    Last edited: Feb 5, 2013
  5. ac_dc_1

    Thread Starter Member

    Jan 27, 2013
    74
    0
    Is the value for the maximum frequency without SR distortion correct?

    Thanks
     
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