Dual op-amp output voltage as function of source

[gfd43tg]

Homework Statement

Find Vo as a function of Vs

Homework Equations

The Attempt at a Solution

My thought process so far is to do KCL and find Vo as a function of Vn2, then Vn2 as a function of Vo1, then Vo1 and Vo as a function of Vn1, then Vn1 as a function of Vs, finally giving me Vo as a function of Vs. This seems extraordinarily difficult to do all those substitutions, but I see nothing else as of this moment

 

[gneill]

Keep in mind the properties of op-amp circuits where negative feedback is provided. How are the potentials on the input terminals related?

I'd suggest beginning with the output stage and determine what V_o is in terms of V_o1. Then KCL at the V_n1 node.

 

[donpacino]

do a kcl at all non driven and non ground nodes.
in other words, do a kcl at the negative nodes of each op-amp.
then solve for the answer

 

[gfd43tg]

Alright following your collected guidance, my friend and I solved it and got the same answer. Thank you! I did not set the voltage at the inputs to zero, no wonder it was so complicated.

 

[The Electrician]

What was your answer?

 

[gfd43tg]

Vo = Vs (Rf1*Rf2*Rf3)/(Rs1(Rs2*Rf3-Rf2*Rf1))

 

[Jony130]

Your answer looks good