AD8253

Rev. 0 | Page 22 of 24

DATA ACQUISITION

The AD8253 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 63 shows the AD825x as part of a total data acquisition

system. The quick slew rate of the AD8253 allows it to condition

rapidly changing signals from the multiplexed inputs. An FPGA

controls the AD7612, AD8253, and ADG1209. In addition,

mechanical switches and jumpers allow users to pin strap the

gains when in transparent gain mode.

This system achieved −116 dB of THD at 1 kHz and a signal-to-

noise ratio of 91 dB during testing, as shown in Figure 62.

–70

–80

–90

–100

–110

–120

–130

–140

–150

–160

–170

–60

–10

–20

–30

–40

–50

0

05

FREQUENCY (kHz)

0

5

1015202530354045

Figure 62. FFT of the AD825x in a Total Data Acquisition System

Using the AD8253 1 kHz Signal

AD8253

2

+IN

–IN

A1

A0

VOUT

REF

DGND

5

3

4

9

1

7

10

11

12

13

14

15

16

6

2

S1A EN

DA

DB

GND

S2A

S3A

S4A

S1B

S2B

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

2kΩ

DGND

Figure 63. Schematic of ADG1209, AD8253, and AD7612 Used with the AD825x in a Total Data Acquisition System