ADA4938-1/ADA4938-2

Data Sheet

Rev. B | Page 22 of 26

Table 10 and Table 11 list several common gain settings, associated

resistor values, input impedances, and output noise densities for

both balanced and unbalanced input configurations. Also shown

are the input common-mode voltages under the given conditions

for different VOCM settings for both a 10 V single supply and

±5 V dual supplies.

Table 10. Differential Ground-Referenced Input, DC-Coupled; See Figure 59

Nominal

Gain (V/V)

RF (Ω)

RG (Ω)

RIN,dm (Ω)

Differential

Output

Noise Density

(nV/√Hz)

Common-Mode Level at +IN, −IN (V)

+VS = 10 V, −VS = 0 V

VOUT,dm = 2.0V p-p

+VS = 5 V, −VS = −5 V

VOUT,dm = 2.0V p-p

VOCM = 2.5V

VOCM = 3.5V

VOCM = 1.0V

VOCM = 3.2V

1

200

200

400

6.5

1.25

1.75

0.50

1.60

2

402

200

400

10.4

0.83

1.16

0.33

1.06

3.16

402

127

254

13.4

0.60

0.84

0.24

0.77

5

402

80.6

161

18.2

0.42

0.58

0.17

0.53

Table 11. Single-Ended Ground-Referenced Input, DC-Coupled, RS = 50 Ω; See Figure 60

Nominal

Gain (V/V)

RF (Ω) RG1 (Ω) RT (Ω) RIN,se (Ω) RG2 (Ω)1

Overall

Gain (V/V)2

Differential

Output

Noise

Density

(nV/√Hz)

Common-Mode Swing at +IN, −IN (V)

+VS = 10 V, −VS = 0 V

VOUT,dm = 2.0 V p-p

+VS = 5 V, −VS = −5 V

VOUT,dm = 2.0 V p-p

VOCM = 2.5 V

VOCM = 3.5 V

VOCM = 0 V

VOCM = 2.0 V

1

200

200

60.4

267

226

0.9

6.2

1.00 to 1.50

1.50 to 2.00

−0.25 to +0.25

0.75 to 1.25

2

402

200

60.4

300

226

1.8

9.8

0.66 to 1.00

1.00 to 1.33

−0.17 to +0.17

0.50 to 0.83

3.16

402

127

66.5

205

158

2.5

11.8

0.48 to 0.72

0.72 to 0.96

−0.12 to +0.12

0.36 to 0.60

5

402

80.6

76.8

138

110

3.6

14.7

0.33 to 0.50

0.50 to 0.67

−0.08 to +0.08

0.25 to 0.42

1

RG2 = RG1 + RTS.

2

Includes effects of termination match.