AD9631/AD9632

REV. A

–16–

A/D Converter Driver

As A/D converters move toward higher speeds with higher reso-

lutions, there becomes a need for high performance drivers that

will not degrade the analog signal to the converter. It is desir-

able from a system’s standpoint that the A/D be the element in

the signal chain that ultimately limits overall distortion. This

places new demands on the amplifiers used to drive fast, high

resolution A/Ds.

With high bandwidth, low distortion and fast settling time the

AD9631 and AD9632 make high performance A/D drivers for

advanced converters. Figure 64 is an example of an AD9631

used as an input driver for an AD872. A 12-bit, 10 Msps A/D

converter.

MSB

BIT2

BIT3

BIT4

BIT5

BIT6

BIT7

BIT8

BIT9

BIT10

BIT11

BIT12

AV

DD

AGND

V

INA

REF GND

REF IN

REF OUT

AV

SS

AV

SS

AGND

OTR

CLK

DRGND

DRV

DD

DGND

DV

DD

19

18

17

16

15

14

13

12

11

10

9

8

24

25

3

26

28

27

1

20

21

23

22

6

7

4

5

V

INB

0.1

µF

–5V ANALOG

AD872

1

7

6

4

3

2

5

1

µF

+5V ANALOG

AD9631

ANALOG IN

0.1

µF

0.1

µF

0.1

µF

DIGITAL OUTPUT

0.1

µF

0.1

µF

10

Ω

49.9

Ω

CLOCK INPUT

0.1

µF

0.1

µF

140

Ω

+5V ANALOG

+5V DIGITAL

+5V DIGITAL

130

Ω

–5V

ANALOG

2

10

µF

10

µF

Figure 64. AD9631 Used as Driver for an AD872, a 12-Bit, 10 Msps A/D Converter