# Input Dynamic range of Op-Amp circuits

Discussion in 'Homework Help' started by testing12, Sep 30, 2011.

1. ### testing12 Thread Starter Member

Jan 30, 2011
80
2
Hello Everyone,

Im looking for some help with calculating the input dynamic range of the op-Amp circuit below. Can someone please direct me?

I know that if V1(t) falls outside the input dynamic range, the circuit saturates, ie goes to either +/- 13 volts..Just not sure how to find the range.

Thank you.

2. ### testing12 Thread Starter Member

Jan 30, 2011
80
2
Here is ym attempt: for a summing amplifier:

V(out)= - (Rf/R1)*v1 -(Rf/R2)*v2

13 = -(33/10) *(v1) - (33/100) *(2)

v1= +/- 4.14 volts

3. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
You effectively have an inverting / summing amplifier.

Vo(t)=-(K1*Vb(t) + K2*Va(t))

K1 & K2 an be deduced from the resistor values

4. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
Looks like you have the idea.

5. ### testing12 Thread Starter Member

Jan 30, 2011
80
2
Thank you sir!!
I wasnt to sure about how the capacitor will affect all this.

6. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
783
At this point the question is only concerned with the voltage Va(t) and not the source 'Sync-out' . If the level at 'Sync-out' was quoted rather than Va(t) then one would have to consider a more complex analysis. What you have done is correct.