Hello all.. I have this circuit:
It's just a basic summer circuit in single supply mode. I don't understand why I cannot resolve the equation similar to the one they have in Texas Instrument's Single Supply Op Amp Collection document.
Please help me understand.
I derived my calculations using superposition. First I derived V_out1 by shorting V2 and V3. Then, I found V_out2 by shoring V2 and V1. Last, I shorted V1 and V3 to find V_out3. I got the following:
V_out1 = - (R2 / R1) * V1 V_out2 = - (R2 / R3) * V3
V_out3 = V2 * [ (R3 || R1) + R2] / R2 = V2 * [ ( (R3 || R1) / R2) + 1] (I treated V_out3 like a basic non-inverting configuration)
Now I have V_out = V_out1 + V_out2 + V_out3, which does not match with TI's document and with my simulation results.
Any insights? Thank you very much!