Data Sheet

AD8250

Rev. C | Page 21 of 24

DATA ACQUISITION

The AD8250 makes an excellent instrumentation amplifier for

use in data acquisition systems. Its wide bandwidth, low distortion,

low settling time, and low noise enable it to condition signals in

front of a variety of 16-bit ADCs.

Figure 59 shows a schematic of the AD825x data acquisition

demonstration board. The quick slew rate of the AD8250 allows

it to condition rapidly changing signals from the multiplexed

inputs. An FPGA controls the AD7612, AD8250, and ADG1209.

In addition, mechanical switches and jumpers allow users to pin

strap the gains when in transparent gain mode.

This system achieved −111 dB of THD at 1 kHz and a signal-to-

noise ratio of 91 dB during testing, as shown in Figure 58.

0

–140

–130

–120

–110

–100

–90

–80

–70

–60

–50

–40

–30

–20

–10

0

5

10

15

20

25

30

35

40

45

50

FREQUENCY (kHz)

Figure 58. FFT of the AD825x DAQ Demo Board Using the AD8250,

1 kHz Signal

AD8250

2

+IN

–IN

A1

A0

OUT

REF

DGND

5

3

4

9

1

7

10

11

12

13

14

15

16

6

2

S1A EN

S2A

S3A

S4A

S1B

S2B

DB

GND

DA

S3B

S4B

A0

A1

JMP

JMP

JMP

+12V –12V

+12V

–12V

JMP

JMP

+5V

+5V

DGND

806Ω

806Ω

806Ω

806Ω

806Ω

806Ω

806Ω

806Ω

0Ω

0Ω 49.9Ω

0Ω

–CH1

+CH1

+CH2

–CH2

+CH3

–CH3

+CH4

–CH4

1nF

2kΩ

2kΩ

0.1µF

GND

+12V

–12V

+

+

10µF

10µF

0.1µF

C3

0.1µF

C4

0.1µF

+5V

+5V

DGND

DGND

R8

2kΩ

+IN

AD7612

ADR435

ADG1209

DGND

ALTERA

EPF6010ATC144-3

8

0Ω

0Ω

1

10

6

WR

9

4

5

8

3

7

+

–

DGND

2k

Ω

DGND

Figure 59. Schematic of ADG1209, AD8250, and AD7612 in the AD825x DAQ Demo Board