Confused with Omp Amplifier Problem - Part B Solution

[Saeed.z]

i am confused with this problem , part b :

http://img85.imageshack.us/img85/1736/ampe.png

my question is : Does Vsat reffer to the right amp or the whole circuit ? or something wrong with this problem ? thanks :)

 

[berkeman]

i am confused with this problem , part b :

http://img85.imageshack.us/img85/1736/ampe.png

my question is : Does Vsat reffer to the right amp or the whole circuit ? or something wrong with this problem ? thanks :)

I don't think there is anything wrong with the problem.

What is that 2nd opamp doing? What is the name for the configuration it is in? What is its output in relation to its input? Does that help you answer your question about which stage saturates first?

 

[Saeed.z]

I don't think there is anything wrong with the problem.

What is that 2nd opamp doing? What is the name for the configuration it is in? What is its output in relation to its input? Does that help you answer your question about which stage saturates first?

it inverts the left hand amp ,, ( the inverting amp ) . Vo = -12 Vs .

my question was : part b says that " assume Vsat =

12 " . Why not

15 ? thanks

 

[berkeman]

it inverts the left hand amp ,, ( the inverting amp ) . Vo = -12 Vs .

my question was : part b says that " assume Vsat =

12 " . Why not

15 ? thanks

No, the 2nd stage is not an inverting stage. The first stage is inverting, but the second is not.

The saturation output voltage of most opamps is less than the power rails, so that's why the Vsat is listed as +/-12V when the rails are at +/-15V. You can get more expensive opamps that have close to rail-to-rail outputs, but the voltages given in this problem are common for general opamps.