AD8597/AD8599

Rev. B | Page 16 of 20

The AD8597/AD8599 are the optimum choice for low noise

performance if the source resistance is kept < 1 kΩ. At higher

values of source resistance, optimum performance with respect

to only noise is obtained with other amplifiers from Analog

Devices. Both voltage noise and current noise need to be consi-

dered. For more information on avoiding noise from grounding

problems and inadequate bypassing, see the AN-345 Application

Note, Grounding for Low- and High-Frequency Circuits. For

general noise theory with extensive calculations, see the

AN-358 Application Note, Noise and Operational Amplifier

Circuits. A good selection table for low noise op amps can

be found in AN-940 Application Note, Low Noise Amplifier

Selection Guide for Optimal Noise Performance. An interesting

note on using one section of a monolithic dual to phase compen-

sate the other section is in the AN-107 Application Note, Active

Feedback Improves Amplifier Phase Accuracy.

+

–

V+

V–

C1

Q36

Q32

R1

R31

R32

D2

D31

D34

OUTPUT

D3

6

INVERTING

INPUT

7

2

3

4

NONINVERTING

INPUT

D1

R18

R19

D2

D41

Q18 Q19

Q19

Q27

Q20

Q28

D42

D39

D40

Figure 59. Simplified Schematic