AD9631AN Analog Devices Inc, AD9631AN Datasheet - Page 14

• Manufacturer Part Number: AD9631AN
• Description: IC OPAMP VF ULDIST 70MA 8DIP
• Manufacturer: Analog Devices Inc

Specifications of AD9631AN

• Rohs Status: RoHS non-compliant
• Amplifier Type: Voltage Feedback
• Number Of Circuits: 1
• Slew Rate: 1300 V/µs
• -3db Bandwidth: 320MHz
• Current - Input Bias: 2µA
• Voltage - Input Offset: 3000µV
• Current - Supply: 17mA
• Current - Output / Channel: 70mA
• Voltage - Supply, Single/dual (±): 6 V ~ 12 V, ±3 V ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Output Type: -
• Gain Bandwidth Product: -

AD9631/AD9632
Pulse Response
Unlike a traditional voltage feedback amplifier, where the slew
speed is dictated by its front end dc quiescent current and
gain bandwidth product, the AD9631 and AD9632 provide
“on-demand” current that increases proportionally to the input
“step” signal amplitude. This results in slew rates (1300 V/ms)
comparable to wideband current feedback designs. This, combined
with relatively low input noise current (2.0 pA/÷Hz), gives the
AD9631 and AD9632 the best attributes of both voltage and
current feedback amplifiers.
Large Signal Performance
The outstanding large signal operation of the AD9631 and AD9632
is due to a unique, proprietary design architecture. In order to
maintain this level of performance, the maximum 550 V-MHz
product must be observed (e.g., @ 100 MHz, V
Power Supply Bypassing
Adequate power supply bypassing can be critical when optimizing
the performance of a high frequency circuit. Inductance in the
power supply leads can form resonant circuits that produce
peaking in the amplifier’s response. In addition, if large current
transients must be delivered to the load, then bypass capacitors
(typically greater than 1 mF) will be required to provide the best
settling time and lowest distortion. A parallel combination of at
least 4.7 mF, and between 0.1 mF and 0.01 mF, is recommended.
Some brands of electrolytic capacitors will require a small series
damping resistor ª4.7 W for optimum results.
Driving Capacitive Loads
The AD9631 and AD9632 were designed primarily to drive
nonreactive loads. If driving loads with a capacitive component is
desired, the best frequency response is obtained by the addition of
a small series resistance as shown in Figure 6. The accompany-
ing graph shows the optimum value for R
load. It is worth noting that the frequency response of the circuit
when driving large capacitive loads will be dominated by the
passive roll-off of R
Figure 6. Driving Capacitive Loads
R
IN
SERIES
R
IN
AD9631/
AD9632
and C
R
F
L
.
R
SERIES
SERIES
1k
R
L
versus capacitive
O
£ 5.5 V p-p).
C
L
–14–
APPLICATIONS
The AD9631 and AD9632 are voltage feedback amplifiers well
suited for applications such as photodetectors, active filters, and
log amplifiers. The devices’ wide bandwidth (320 MHz), phase
margin (65 ), low current noise (2.0 pA/÷Hz), and slew rate
(1300 V/ms) give higher performance capabilities to these appli-
cations over previous voltage feedback designs.
With a settling time of 16 ns to 0.01% and 11 ns to 0.1%, the
devices are an excellent choice for DAC I/V conversion. The same
characteristics along with low harmonic distortion make them
a good choice for ADC buffering/amplification. With superb
linearity at relatively high signal frequencies, the AD9631 and
AD9632 are ideal drivers for ADCs up to 12 bits.
Operation as a Video Line Driver
The AD9631 and AD9632 have been designed to offer outstand-
ing performance as video line drivers. The important specifications
of differential gain (0.02%) and differential phase (0.02 ) meet
the most exacting HDTV demands for driving video loads.
Figure 7. Recommended R
V
IN
40
30
20
10
CABLE
0
75
274
Figure 8. Video Line Driver
75
5
AD9631/
AD9632
+V
–V
274
S
S
10
0.1 F
0.1 F
10 F
10 F
C
L
SERIES
– pF
15
vs. Capacitive Load
75
CABLE
75
20
75
REV. C
25
V
OUT