For the DAC circuit shown demonstrate that the output voltag

For the DAC circuit shown, demonstrate that the output voltage is 11 V when the input is 1 0 1 1.

Solution

The OpAmp is in negative feedback so the voltage of the -ve input will try to keep its input at V=0

So the output voltage V_out = -(R_f / R_1) V_in

Since the voltages accross resistance B is zero it is cut-off and resistances A, C and D are parrallely connected.

This means R_1 = 12.5 || 50 || 100 = 100/11 k ohm and R_f = 20 k ohm along with V_in = 5 volt

V_out = - (20/(100/11)) x 5 = - 11 volt