Datasheet

AD8010
–11–REV. B
Table I. –3 dB Bandwidth and Slew Rate vs. Closed-Loop
Gain and Resistor Values
Package: N-8
Closed-Loop –3 dB BW Slew Rate
Gain R
F
()R
G
() (MHz) (V/s)
+1 453
∞ 285 900
[phone]
+5 348 86.6 200 800
+10 562 61.9 120 550
Package: R-16
Closed-Loop –3 dB BW Slew Rate
Gain R
F
()R
G
() (MHz) (V/s)
+1 412
∞ 245 900
[phone]
+5 392 97.6 160 800
+10 604 66.5 95 550
Package: SO-8
Closed-Loop –3 dB BW Slew Rate
Gain R
F
()R
G
() (MHz) (V/s)
+1 392
∞ 345 950
[phone]
+5 348 86.6 220 1000
+10 499 54.9 135 650
1. V
O
= 0.2 V p-p for –3 dB Bandwidth.
2. V
O
= 2 V p-p for Slew Rate.
3. Bypassing per Figure 29.
150
50
R
F
R
G
V
OUT
18.75
V
IN
Figure 32. Test Circuit for Table I
Closed-Loop Gain and Bandwidth
The AD8010 is a current feedback amplifier optimized for use
in high performance video and data acquisition applications.
Since it uses a current feedback architecture, its closed-loop
–3 dB bandwidth is dependent on the magnitude of the feedback
resistor. The desired closed-loop bandwidth and gain are obtained
by varying the feedback resistor (R
F
) to set the bandwidth, and
varying the gain resistor (R
G
) to set the desired gain. The char-
acteristic curves and specifications for this data sheet reflect the
performance of the AD8010 using the values of R
F
noted at the
top of the specifications table. If a greater –3 dB bandwidth
and/or slew rate is required (at the expense of video performance),
Table I provides the recommended resistor values. Figure 32
shows the test circuit and conditions used to produce Table I.
Effect of Feedback Resistor Tolerance on Gain Flatness
Because of the relationship between the 3 dB bandwidth and the
feedback resistor, the fine scale gain flatness will, to some extent,
vary with feedback resistor tolerance. It is therefore recommended
that resistors with a 1% tolerance be used if it is desired to main-
tain flatness over a wide range of production lots. In addition,
resistors of different construction have different associated para-
sitic capacitance and inductance. Metal-film resistors were used
for the bulk of the characterization for this data sheet. It is pos-
sible that values other than those indicated will be optimal for
other resistor types.
Quality of Coaxial Cable
Optimum flatness when driving a coax cable is possible only
when the driven cable is terminated at each end with a resistor
matching its characteristic impedance. If the coax was ideal,
then the resulting flatness would not be affected by the length of
the cable. While outstanding results can be achieved using inex-
pensive cables, it should be noted that some variation in flatness
due to varying cable lengths may be experienced.