Question

Implement the following function using two op-amps and the required number of resistors

V_o = V₁ - 2V₂ + 3V₃ - 4V₄

Answer 1

Applying the KCL at node 1

$\frac{0-V_1}{1K\Omega}-\frac{0-2V_2}{1K\Omega}+\frac{0-V_{01}}{1K\Omega}=0$

$V_{01}=-V_1-2V_2$

Applying the KCL at node 2

$\frac{0-V_1}{1K\Omega}+\frac{0-3V_3}{1K\Omega}+\frac{0-4V_{4}}{1K\Omega}+\frac{0-V_{0}}{1K\Omega}=0$

$-V_{01}-3V_3-4V_4=V_0$

$V_O=-[-V_1-2V_2]-3V_3-4V_4$

$V_O=V_1+2V_2-3V_3-4V_4$