OPA145ID datasheet(21/40 Pages) TI1

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(A) Noise in Noninverting Gain Configuration

GND

Source

GND

Source

(B) Noise in Inverting Gain Configuration

:1; '

1 =

l1+42

p„¨:A

;2 +:A

;2 +

41æ42

o2+:E

„ 45

;2 +

„

d41„42

41 + 42

hp2 >8

4/5

:2; A

5 =

¥4„G$„6(-)„45 d 8

¾*V

:3; A

41æ42 =

¨4„G

„ 6(-) „

d41„42

41 + 42

h d 8

¾*V

:4; G

$ = 1.38065

„ 10

F23

d ,

:5; 6(-) = 237.15+6(°%) >-?

Noise at the output is given as EO, where

:6; '

1 =

l1+ 42

45 + 41

p„¨:A

;2 +

41+45 æ42

o2+FE

„

H:45 +41;„42

45 + 41 + 42 IG

4/5

:7; A

41+45 æ42 =

¨4„G

„ 6(-) „

H:45 +41;„42

45 + 41 + 42 I

d 8

¾*V

:8; G

$ = 1.38065

„ 10

F23

d ,

:9; 6(-) = 237.15+6(°%) >-?

Thermal noise of RS

Thermal noise of R1 || R2

Boltzmann Constant

Temperature in kelvins

Boltzmann Constant

Temperature in kelvins

Thermal noise of (R1 + RS) || R2

OPA145, OPA2145, OPA4145

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SBOS427 – JUNE 2017

Product Folder Links: OPA145 OPA2145 OPA4145

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Feature Description (continued)

(1)

eN is the voltage noise of the amplifier. For the OPAx145 series of operational amplifiers, eN = 7 nV/√Hz at 1 kHz.

(2)

iN is the current noise of the amplifier. For the OPAx145 series of operational amplifiers, iN = 0.8 fA/√Hz at 1 kHz.

(3)

For additional resources on noise calculations visit TI's Precision Labs Series.

Figure 40. Noise Calculation in Gain Configurations

OPA145ID Datasheet(PDF) 21 Page - Texas Instruments

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