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OPA1602_15 Datasheet, PDF (12/29 Pages) Texas Instruments – High-Performance, Bipolar-Input AUDIO OPERATIONAL AMPLIFIERS
OPA1602
OPA1604
SBOS474B – APRIL 2011 – REVISED NOVEMBER 2011
A) Noise in Noninverting Gain Configuration
R2
R1
EO
RS
VS
Noise at the output:
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EO2 =
1+
R2
R1
2
en2 +
2
2
R2
R1
e12 + e22 +
1+
R2
R1
es2
Where eS =
e1 =
e2 =
4kTRS = thermal noise of RS
4kTR1 = thermal noise of R1
4kTR2 = thermal noise of R2
B) Noise in Inverting Gain Configuration
R2
R1
Noise at the output:
2
EO2 =
1 + R2
R1 + RS
en2 +
R2
R1 + RS
2
e12 + e22 +
R2
R1 + RS
2
es2
RS
VS
EO
Where eS =
e1 =
e2 =
4kTRS = thermal noise of RS
4kTR1 = thermal noise of R1
4kTR2 = thermal noise of R2
Note: For the OPA160x series of op amps at 1kHz, en = 2.5nV/√Hz and in = 1.8pA√Hz.
Figure 34. Noise Calculation in Gain Configurations
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