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Op Amp Noise
This simplifies the gain calculation:
R
E 0 E 2
in
R 1
2 e n 1 R 2
2
R 1
(10–19)
where e n = the total noise over the bandwidth of interest.
10.5.5 Noninverting Op Amp Circuit Noise
Taking the simplified equivalent op amp circuit from Paragraph 10.5.2 as the base, the
noise equivalent of a noninverting op amp circuit is shown in Figure 10–11:
R 2
_
_
R 1
Noiseless
Op Amp
E0
Ein
+
en
+
Figure 10–11.
Noninverting Equivalent Op Amp Circuit Noise Model
The gain of this circuit is:
E 0 E in
1 R 2
2
R 1
e n 1 R 2
2
R 1
(10–20)
Op Amp Noise Theory and Applications
10-17