AD8061/AD8062/AD8063

Rev. E | Page 15 of 20

TIME (ns)

2.0

0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

4

8

12

16

20

24

28

32

2V TO 3V STEP

2.1V TO 3.1V STEP

2.2V TO 3.2V STEP

2.3V TO 3.3V STEP

2.4V TO 3.4V STEP

Figure 47. Output Rising Edge for 1 V Step at

As the saturation point of the output stage is approached, the

output signal shows increasing amounts of compression and

clipping. As in the input headroom case, the higher frequency

signals require a bit more headroom than lower frequency

signals. Figure 16, Figure 17, and Figure 18 illustrate this point,

plotting typical distortion vs. output amplitude and bias for

gains of 2 and 5.

OVERLOAD BEHAVIOR AND RECOVERY

Input

The specified input common-mode voltage of the AD8061/

AD8062/AD8063 is −200 mV below the negative supply to

within 1.8 V of the positive supply. Exceeding the top limit

results in lower bandwidth and increased settling time as seen

in Figure 46 and Figure 47. Pushing the input voltage of a unity-

gain follower beyond 1.6 V within the positive supply leads to

the behavior shown in Figure 48—an increasing amount of

output error and much increased settling time. Recovery time

from input voltages 1.6 V or closer to the positive supply is

approximately 35 ns, which is limited by the settling artifacts

caused by transistors in the input stage coming out of saturation.

The AD8061/AD8062/AD8063 family does not exhibit phase

reversal, even for input voltages beyond the voltage supply rails.

Going more than 0.6 V beyond the power supplies turns on

protection diodes at the input stage, which greatly increases the

current draw of the device.

TIME (ns)

2.1

0

2.3

100

VOLTAGE STEP

FROM 2.4V TO 3.4V

2.5

2.7

2.9

3.1

3.3

3.5

3.7

VOLTAGE STEP

FROM 2.4V TO 3.6V

VOLTAGE STEP

FROM 2.4V TO 3.8V,

4V AND 5V

200

300

400

500

600

Figure 48. Pulse Response for G = 1 Follower,

Input Step Overloading the Input Stage

Output

Output overload recovery is typically within 40 ns after the

amplifier’s input is brought to a nonoverloading value. Figure 49

shows output recovery transients for the amplifier recovering

from a saturated output from the top and bottom supplies to a

point at midsupply.

TIME (ns)

–0.2

OUTPUT VOLTAGE

5V TO 2.5V

0.2

0.6

1.0

1.4

1.8

2.2

2.6

3.0

3.4

3.8

4.2

4.6

5.0

10

20

30

40

50

60

70

OUTPUT VOLTAGE

0V TO 2.5V

INPUT VOLTAGE

EDGES

R

5V

2.5V

R

–

–

0