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!