Total input noise of a large selection of op-amps


I have calculated the total input noise of a large selection of op-amps to serve as a general selection table for different circuits when driven by some common signal sources. One thing that is immediately noticeable is that chips that work well for microphone amplifiers do not give the same low noise performance when driven by a guitar pickup or piezo transducer. All of the measurements are for 1k Hz. which is commonly used in specifications.

A 150 ohm interface is common for microphone amplifiers, a 5k pickup would be a single coil and a 12k pickup would be a typical humbucker. Piezo pickups are basically capacitive but we can calculate the reactance of one at 1k Hz and use that as the basis for the noise table.

The numbers in the table are not meant to be 100% exact however they will be correct relative to each other for purposes of selecting an op-amp for use in a design. Lower noise numbers are quieter; high slew rates will indicate a wider bandwidth. Noise specs at 1k Hz were used.

Two commonly used chips stand out as being poor performers, the LM324 and the TL062, while the common TL072 gives good results across the board.

Noise figures for comparative purposes only:

Total Calculated Noise, nV

 

150ohm Mic

5k Pickup

12k Pickup

Piezo Pickup

Slew Rate V/S

AD711

18.1

20.6

23.2

95.1

16

AD797

2.4

14.3

28.2

1064.1

20

INA103

2.5

14.3

28.2

1064.1

15

LF353

25.1

26.9

28.9

96.6

13

LM318

23.1

25.2

27.9

281.9

70

LM324

23.1

25.2

27.9

281.9

0.25

LM833

5.0

11.2

16.4

281.0

7

LT1028

2.4

11.2

18.9

538.1

15

LT1007

3.3

10.4

15.6

231.6

2.5

LT1028

2.4

11.2

18.9

538.1

30

LT1115

2.4

11.7

20.6

642.8

20

MC33178

7.8

12.5

16.5

122.8

2

MC33272

18.1

20.7

23.9

281.5

10

NE5532

5.5

11.7

17.6

382.6

9

OP227

3.3

10.4

15.6

231.6

2.8

OP275

6.4

13.9

24.0

800.5

22

OPA27

3.9

10.6

15.7

231.6

1.9

OPA270

3.9

10.6

15.7

231.6

3

OPA2111

8.3

12.7

16.6

93.7

2

OPA2227

3.7

10.6

15.7

231.6

2.3

OPA2604

11.2

14.8

18.3

94.0

25

RC4559

10.2

14.3

18.7

281.1

2

RC4560

7.3

12.3

16.9

231.7

1.6

SSM2017

2.98

13.6

27.9

1064.1

17

SSM2275

8.3

13.5

19.9

486.1

12

TL052

18.1

20.6

23.2

95.1

18

TL062

42.1

43.5

46.1

539.8

3.5

TL072

18.1

20.6

23.2

95.1

13

TLC2272

9.3

13.4

17.1

93.7

3.6

2000 Jack Orman - May not be reproduced without permission.