Combined Inverting and Non-inverting Inputs
The general case of input configuration is a combination of the previous two cases. That is, we allow for both inverting and non-inverting inputs. The general configuration is shown in Figure (13).
The previous circuits can be considered as special cases of this general problem. The output relationship is found by applying superposition as follows. Equation (29)
is derived by combining Equation (17)
with Equation (25)
Equation (29) represents a general result which will prove useful in analyzing a wide variety of circuits. With equations this complex, it is always a good idea to verify that the units on each side of the equality match. Indeed, the units on both sides of the equality are “volts”.
Analyze the following circuits using the TINACloud online circuit simulator software to determine Vout in terms of the input voltages by clicking the links below.