SLOA011B January 2018 – July 2021 LF347 , LF353 , LM348 , MC1458 , TL022 , TL061 , TL062 , TL071 , TL072 , UA741
Substituting a = ∞ Equation 1 into Equation 24 results in
Recall that in equation Equation 6 we stated that V_{d}, the voltage difference between V_{n} and V_{p}, was equal to zero so that V_{n} = V_{p}. Still they are not shorted together. Rather there is said to be a virtual short between V_{n} and V_{p}. The concept of the virtual short further simplifies analysis of the inverting op amp circuit in Figure 3-1.
Using the virtual short concept, we can say that
In this configuration, the inverting input is a virtual ground.
We can write the node equation at the inverting input as
Since V_{n} = 0, rearranging, and solving for A we get
The same result is derived more easily than in (Equation 24. Using the virtual short (or virtual ground) concept reduced solving the inverting amplifier, shown in Figure 3-1, to solving a single node equation.