.PS
cct_init

# Usual defs...
qrt=dimen_/4;
hlf=dimen_/2;
dim=dimen_;

F1:opamp(right_,,,,PR)
line right_ hlf
line from F1.In1 left_ hlf
"$v_1$ " ljust_
line from F1.In2 left_ qrt
line down_ hlf then right_ qrt
resistor(right_); rlabel(,R_2,)
line right_ qrt
line to (Here, F1.Out);dot

move to F1.In1 then down_ 2.5*dim

F2:opamp(right_,,,,P) with .In1 at Here
line from F2.Out right_ hlf
line from F2.In1 left_ qrt
line from F2.In2 left_ hlf
"$v_2$ " ljust_
move to F2.In1 then left_ qrt
line up_ hlf then right_ qrt
resistor(right_);llabel(,R_2,)
line right_ qrt
line to (Here, F2.Out);dot

move to F1.In1 then right_ 2.75*dim then down_ 1.25*dim

Op1:opamp(right_,,,,P) with .In1 at Here
line from Op1.Out right_ hlf
" $v_o$" ljust_
line from Op1.In1 left_ qrt
resistor(left_); rlabel(,R_3,)
line from Op1.In2 left_ qrt; dot
resistor(left_); llabel(,R_3,)
move right_ dim
resistor(down_); llabel(,R_3,)
ground(,T)
move to Op1.In1 then left_ qrt; dot
line up_ hlf then right_ qrt
resistor(right_);llabel(,R_3,)
line right_ qrt
line to (Here, Op1.Out);dot

move to Op1.In1 then left_ 1.25*dim
line to (Here,F1.Out)

move to Op1.In2 then left_ 1.25*dim
line to (Here,F2.Out)

move to F1.In2 then left_ qrt then down_ hlf
dot; resistor(down_);rlabel(,R_1); dot

"\tiny Instrumentation2" at (3.5*dim, -3*dim) rjust_ 
.PE