An OPAMP with input offset voltage

[fgda]

1. The problem statement, all variables and given/known data
**broken link removed**


2. Relevant equations
Superposition
Non-inverting OPAMP: V_out = (1 + R/R)V_in = 2*V_in2
Inverting OPAMP: V_out = -V_in
V_os = 2.5mV

3. The attempt at a solution

1. V_in enabled, V_os disabled

V_out1 = -V_in

2. V_os enabled, V_in disabled

To get V_out2, use the non inv. equation where V_in2 is equal to V_1 + V_os
where V_1 is the node between R and R at the middle bottom of the circuit.
V_out2 = 2*(V_1 + V_os)

3. V_out = V_out1 + V_out2




Is this the correct approach?

Thanks in advance

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I'm pretty sure that step 2 is correct. The professor did an example in class that was similar enough to that case. But in step 1, I have input voltage at both OPAMP terminals so I do not know what to do. I'd rather take the OPAMP as a black box with a characteristic equation if possible.

 

[rahdirs]

@fgda:Your approach is correct,but your calculation of Vout1 is wrong,there is a feedback from output to non inverting terminal.
Using concept of virtual ground & circuit theory,you get
Vout1/6 = (Vin-Vout/2), you'll get Vout1 = (3/4)*Vin = 1.65V.(when V_os is sisabled)
In couldn't understand your calculation of Vout2,could you edit it(elaborate).What is V_1????