Page 1120 - Basic Electrical Engineering

Figure 17.6 (a) Op-amp used as an adder or summer; (b) op-amp used as a differential amplifier

Assuming point Q at potential υ, and assuming no current flowing through

the amplifier

and V = Aυ
0

or,

If A → a, v → 0 (virtual ground)
we can write

If

Now if we make