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0.1

1

10k

100k

Frequency (MHz)

21

18

15

12

9

6

G = +8

G = —8

G047

Limited Output, ADC Input Driver

OPA698

4

2

3

7

5

8

6

+3.5V

+1.5V

V

IN

REFB

REFT

IN

0.1

∝F

100pF

V

V

0.1

∝F

0.1

∝F

0.1

∝F

402

Ω

24.9

Ω

562

Ω

102

Ω

402

Ω

715

Ω

715

Ω

102

Ω

562

Ω

ADS822

10−Bit

Data

INT/EXT

RSEL

+V

CC

GND

S0038−01

10-Bit

40MSPS

Limited Output, Differential ADC Input Driver

OPA698M

SGLS287A – MAY 2005 – REVISED MARCH 2006

TYPICAL APPLICATIONS (continued)

Figure 50. G = +8 and –8 Frequency Response

Figure 51 shows a simple ADC driver that operates on a single supply, and gives excellent distortion

performance. The limit voltages track the input range of the converter, completely protecting against input

overdrive. Note that the limiting voltages have been set 100 mV above/below the corresponding reference

voltage from the converter.

Figure 51. Single Supply, Limiting ADC Input Driver

Figure 52 shows a differential ADC driver that takes advantage of the OPA698 limiters to protect the input of the

ADC.

16

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