Datasheet

AD810
REV. A
–13–
of the disable the disable pin for ±5 V supplies. If driven by
complementary output CMOS logic (such as the 74HC04), the
disable time (until the output goes high impedance) is about
100 ns and the enable time (to low impedance output) is about
170 ns on ±5 V supplies. The enable time can be extended to
about 750 ns by using open drain logic such as the 74HC05.
When operated on ±15 V supplies, the AD810 disable pin may
be driven by open drain logic such as the 74C906. In this case,
adding a 10 kΩ pull-up resistor from the disable pin to the plus
supply will decrease the enable time to about 150 ns. If there is
a nonzero voltage present on the amplifier's output at the time it
is switched to the disabled state, some additional decay time will
be required for the output voltage to relax to zero. The total
time for the output to go to zero will generally be about 250 ns
and is somewhat dependent on the load impedance.
OPERATION AS A VIDEO LINE DRIVER
The AD810 is designed to offer outstanding performance at
closed-loop gains of one or greater. At a gain of 2, the AD810
makes an excellent video line driver. The low differential gain
and phase errors and wide –0.1 dB bandwidth are nearly
independent of supply voltage and load (as seen in Figures 49
and 50).
AD810
75Ω
7
3
2
3
0.1µF
+V
S
6
–V
S
4
0.1µF
V
IN
V
OUT
715Ω
75Ω
CABLE
75Ω
75Ω
75Ω
CABLE
715Ω
Figure 47. A Video Line Driver Operating at a Gain of +2
GAIN = +2
R
L
= 150Ω
±2.5V
V
S
= ±15V
±5V
±2.5V
PHASE
GAIN
0
–5
10 100
–1
–2
–3
–4
1
1 1000
0
–45
–90
–135
–180
–225
–270
CLOSED-LOOP GAIN – dB
PHASE SHIFT – Degrees
FREQUENCY – MHz
±5V
V
S
= ±15V
Figure 48. Closed-Loop Gain and Phase vs. Frequency,
G = +2, R
L
= 150, R
F
= 715 Ω
0.10
0
15
0.03
0.01
6
0.02
5
0.06
0.04
0.05
0.07
0.08
0.09
1413121110987
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0
GAIN
PHASE
GAIN = +2
R
F
= 715Ω
R
L
= 150Ω
f
C
= 3.58MHz
100 IRE
MODULATED RAMP
SUPPLY VOLTAGE – ± Volts
DIFFERENTIAL GAIN – %
DIFFERENTIAL PHASE – Degrees
Figure 49. Differential Gain and Phase vs. Supply Voltage
100k
1M 100M10M
+0.1
0
–0.1
–0.1
0
+0.1
NORMALIZED GAIN – dB
FREQUENCY – Hz
R
L
= 150Ω
R
L
= 1k
±15V
±5V
±15V
±5V
±2.5
±2.5
Figure 50. Fine-Scale Gain (Normalized) vs. Frequency
for Various Supply Voltages, Gain = +2, R
F
= 715 Ω
110
40
20
2
30
70
50
60
80
90
100
1816141210864
–3dB BANDWIDTH – MHz
SUPPLY VOLTAGE - ±Volts
PEAKING 1.0dB
PEAKING 0.1dB
G = +2
R
L
= 150Ω
V
O
= 250mV p-p
R
F
= 500
R
F
= 750
R
F
= 1k
≤
≤
Figure 51. –3 dB Bandwidth vs. Supply Voltage,
Gain = +2, R
L
= 150 Ω