Page 432 - Op Amps Design, Applications, and Troubleshooting
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408 SPECIALIZED DEVICES
The voltage on the output of AI can be found by applying Kirchhoff's Volt-
age Law as follows:
Similarly, the voltage at the output of A 2 is computed as
The operation of the subtracter circuit (A 3) was discussed in Chapter 9 and
will not be repeated here. The output, you will recall, is simply the difference
between its inputs. In the present case, the output of A 3 will be
We can apply some basic algebraic manipulations to determine an important
equation for voltage gain. We have already determined the following relation-
ships (with polarities shown in Figure 11.2):
Substituting and simplifying gives us the following results:
