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OPA698

+5V

-5V

V

IN = 1VPP

200

Ω

24.9

Ω

1k

Ω

1k

Ω

0.01

µF

10pF

10pF

0.01

µF

24.9

Ω

100

Ω

100

Ω

OPA698

+5V

-5V

200

Ω

+1.1V

-1.1V

IN

V

CM

ADC

IN

+1.1V

4V

PP

-1.1V

200

Ω

S0040-01

Precision Half-Wave Rectifier

OPA698

6

V

O

-V

S = -5V

+V

S = +5V

V

IN

2

3

4

7

8

5

402

Ω

402

Ω

200

Ω

NC

S0039-01

OPA698M

SGLS287A – MAY 2005 – REVISED MARCH 2006

TYPICAL APPLICATIONS (continued)

Two OPA698s are used. The first one is an inverting configuration at a gain of –2. The second one is in a

noninverting configuration at a gain of +2. Each amplifier is swinging 2 VPP providing a 4-VPP differential signal to

drive the input of the ADC. Limiters have been set 100 mV away from the magnitude of each amplifier's

maximum signal to provide input protection for the ADC, while maintaining an acceptable distortion level.

Figure 52. Single-to-Differential AC-Coupled, Output Limited ADC Driver

Figure 53 shows a half-wave rectifier with outstanding precision and speed. VH (pin 8) defaults to a voltage

between 3.1 V and 3.8 V if left open, while the negative limit is set to ground.

Figure 53. Precision Half-Wave Rectifier

The gain for the circuit in Figure 53 is set at +2. Figure 54 shows a 100-MHz sine-wave amplifier, with a gain of

+2 and rectified.

17

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