AD848JR Analog Devices Inc, AD848JR Datasheet - Page 8

• Manufacturer Part Number: AD848JR
• Description: IC OPAMP GP 175MHZ LP 32MA 8SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD848JR

• Slew Rate: 300 V/µs
• Amplifier Type: General Purpose
• Mounting Type: Surface Mount
• Rohs Status: RoHS non-compliant
• Number Of Circuits: 1
• Gain Bandwidth Product: 175MHz
• Current - Input Bias: 3.3µA
• Voltage - Input Offset: 200µV
• Current - Supply: 5.1mA
• Current - Output / Channel: 32mA
• Voltage - Supply, Single/dual (±): ±4.5 V ~ 18 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 8-SOIC (3.9mm Width)
• No. Of Amplifiers: 1
• Bandwidth: 175MHz
• No. Of Pins: 8
• Peak Reflow Compatible (260 C): No
• Leaded Process Compatible: No
• Output Type: -
• -3db Bandwidth: -
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

AD848/AD849
AD848/AD849–Applications
GROUNDING AND BYPASSING
In designing practical circuits with the AD848 or AD849, the
user must remember that whenever high frequencies are
involved, some special precautions are in order. Circuits must
be built with short interconnect leads. A large ground plane
should be used whenever possible to provide a low resistance,
low inductance circuit path, as well as minimizing the effects of
high frequency coupling. Sockets should be avoided because the
increased interlead capacitance can degrade bandwidth.
Feedback resistors should be of low enough value to assure that
the time constant formed with the capacitances at the amplifier
summing junction will not limit the amplifier performance.
Resistor values of less than 5 k are recommended. If a larger
resistor must be used, a small (< 10 pF) feedback capacitor in
parallel with the feedback resistor, R
sate for the input capacitances and optimize the dynamic per-
formance of the amplifier.
Power supply leads should be bypassed to ground as close as
possible to the amplifier pins. 0.1 F ceramic disc capacitors are
recommended.
VIDEO LINE DRIVER
The AD848 functions very well as a low cost, high speed line
driver of either terminated or unterminated cables. Figure 22
shows the AD848 driving a doubly terminated cable.
The termination resistor, R
impedance of the cable) minimizes reflections from the far end
of the cable. While operating off
maintains a typical slew rate of 200 V/ s, which means it can
drive a 1 V, 24 MHz signal on the terminated cable.
A back-termination resistor (R
impedance of the cable) may be placed between the AD848
output and the cable in order to damp any reflected signals
caused by a mismatch between R
impedance. This will result in a “cleaner” signal, although it
requires that the op amp supply 2 V to the output in order to
achieve a 1 V swing at the line.
Figure 23. AD848 Driving a Capacitive Load
Figure 22. Video Line Driver
T
, (when equal to the characteristic
BT
, also equal to the characteristic
T
5 V supplies, the AD848
and the cable’s characteristic
F
, may be used to compen-
100pF
LOAD
1000pF
LOAD
–8–
Often termination is not used, either because signal integrity
requirements are low or because too many high frequency
signals returned to ground contaminate the ground plane.
Unterminated cables appear as capacitive loads. Since the
AD848 and AD849 are stable into any capacitive load, the op
amp will not oscillate if the cable is not terminated; however
pulse integrity will be degraded. Figure 23 shows the AD848
driving both 100 pF and 1000 pF loads.
LOW NOISE PRE-AMP
The input voltage noise spectral densities of the AD848 and the
AD849 are shown in Figure 24. The low wideband noise and
high gain bandwidths of these devices makes them well suited as
pre-amps for high frequency systems.
Input voltage noise will be the dominant source of noise at the
output in most applications. Other noise sources can be
minimized by keeping resistor values as small as possible.
Mini-DIP (N) Package
Figure 24. Input Voltage Noise Spectral Density
Dimensions shown in inches and (mm).
Small Outline (R) Package
OUTLINE DIMENSIONS
Cerdip (Q) Package
REV. B