# 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?
$

w*Vomax=SR

2*pi*fomax*vomax=SR

fomax=SR/(2*pi*vomax)

$

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

*$

w*vomáx=SR
2pi*f*5=4*10^6

f=127,3385 kHZ

f<=127,3385 kHZ
$

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
726
$
34dB= 20 \cdot log \frac{V_out}{V_in}
$

Re-arranging:

$
V_out = V_in \cdot 10^{\frac{34}{20}}
$

Assuming V_in = 1V

$
V_out = 50.11872V
$

Therefore, the Voltage gain is about 50.12.

Checking our work...
$
dB=20 \cdot log(\frac{50.11872}{1})
dB = 34dB
$

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