AD8616/AD8618

Rev. A | Page 13 of 16

OVERLOAD RECOVERY TIME

Overload recovery time is the time it takes the output of the

amplifier to come out of saturation and recover to its linear

region. Overload recovery is particularly important in

applications where small signals must be amplified in the

presence of large transients. Figure 42 and Figure 43 show the

positive and negative overload recovery times of the AD8616. In

both cases, the time elapsed before the AD8616 comes out of

saturation is less than 1 µs. In addition, the symmetry between

the positive and negative recovery times allows for excellent

signal rectification without distortion to the output signal.

TIME (1

µs/DIV)

–50mV

+2.5V

0V

0V

Figure 42. Positive Overload Recovery

TIME (1

µs/DIV)

+50mV

–2.5V

0V

0V

Figure 43. Negative Overload Recovery

D/A CONVERSION

The AD8616 can be used at the output of high resolution DACs.

Their low offset voltage, fast slew rate, and fast settling time

make the parts suitable to buffer voltage output or current

output DACs.

Figure 44 shows an example of the AD8616 at the output of the

AD5542. The AD8616’s rail-to-rail output and low distortion

help maintain the accuracy needed in data acquisition systems

and automated test equipment.

AD5542

UNIPOLAR

OUTPUT

AGND

DGND

REFS

1/2

AD8616

REFF

SERIAL

INTERFACE

0.1

µF

0.1

µF

10

µF

5V

2.5V

+

CS

DIN

SCLK

LDAC*

Figure 44. Buffering DAC Output

LOW NOISE APPLICATIONS

Although the AD8618 typically has less than 8 nV/√Hz of

voltage noise density at 1 kHz, it is possible to reduce it further.

A simple method is to connect the amplifiers in parallel, as

shown in Figure 45. The total noise at the output is divided by

the square root of the number of amplifiers. In this case, the

total noise is approximately 4 nV/√Hz at room temperature.

The 100 Ω resistor limits the current and provides an effective

output resistance of 50 Ω.

V–

R3

100

Ω

R1

10

Ω

V+

3

2

1

R2

1k

Ω

V–

R6

100

Ω

R4

10

Ω

V+

3

2

1

R5

1k

Ω

V–

R9

100

Ω

R7

10

Ω

V+

3

2

1

R8

1k

Ω

V–

R12

100

Ω

R10

10

Ω

V+

3

2

1

R11

1k

Ω

Figure 45. Noise Reduction