Datasheet

R
1
R
2
E
O
R
1
R
2
E
O
R
S
V
S
R
S
V
S
A)NoiseinNoninvertingGainConfiguration
B)NoiseinInvertingGainConfiguration
Noiseattheoutput:
Wheree =
S
4kTR
S
4kTR
1
4kTR
2
=thermalnoiseofR
S
=thermalnoiseofR
1
=thermalnoiseofR
2
e =
1
e =
2
Noiseattheoutput:
E =
O
2
1+
R
2
R +R
1 S
R
2
R +R
1 S
2 22
Wheree =
S
4kTR
S
4kTR
1
4kTR
2
=thermalnoiseofR
S
=thermalnoiseofR
1
=thermalnoiseofR
2
e =
1
e =
2
R
2
R +R
1 S
2
1+
R
2
R
1
1+
R
2
R
1
2
R
2
R
1
2
e +e +
1 2
2 2
E =
O
2
e +
n
2
e
s
2
e +e +
1 2
2 2
e
s
2
e +
n
2
OPA1652
OPA1654
www.ti.com SBOS477 –DECEMBER 2011
Note: For the OPA165x series of op amps at 1kHz, e
n
= 4.5nV/√Hz.
Figure 38. Noise Calculation in Gain Configurations
Copyright © 2011, Texas Instruments Incorporated 13
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