Page 102 - Op Amps Design, Applications, and Troubleshooting
P. 102
Inverting Summing Amplifier 85
where A OL is the open-loop gain of the op amp at the specified frequency and Y is
computed as follows:
Now let us compute the output impedance for the circuit in Figure 2.20. First
we compute the value of the parallel combination of input resistors (R x)'<
Then we use this value to compute the factor Y, Equation (2.35):
Next we determine the value of A OL at the frequency of interest, using Equation
(2.16). We will use the worst-case value that occurs at the highest input frequency
(10 kilohertz):
