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a
250 MHz, General Purpose
Voltage Feedback Op Amps
AD8047/AD8048
The AD8047 and AD8048’s low distortion and cap load drive
make the AD8047/AD8048 ideal for buffering high speed
ADCs. They are suitable for 12 bit/10 MSPS or 8 bit/60 MSPS
ADCs. Additionally, the balanced high impedance inputs of the
voltage feedback architecture allow maximum flexibility when
designing active filters.
The AD8047 and AD8048 are offered in industrial (–40°C to
+85°C) temperature ranges and are available in 8-pin plastic
DIP and SOIC packages.
5ns1V
Figure 1. AD8047 Large Signal Transient Response,
V
O
= 4 V p-p, G = +1
FEATURES
Wide Bandwidth AD8047, G = +1 AD8048, G = +2
Small Signal 250 MHz 260 MHz
Large Signal (2 V p-p) 130 MHz 160 MHz
5.8 mA Typical Supply Current
Low Distortion, (SFDR) Low Noise
–66 dBc typ @ 5 MHz
–54 dBc typ @ 20 MHz
5.2 nV/√Hz (AD8047), 3.8 nV/√Hz (AD8048) Noise
Drives 50 pF Capacitive Load
High Speed
Slew Rate 750 V/µs (AD8047), 1000 V/µs (AD8048)
Settling 30 ns to 0.01%, 2 V Step
±3 V to ±6 V Supply Operation
APPLICATIONS
Low Power ADC Input Driver
Differential Amplifiers
IF/RF Amplifiers
Pulse Amplifiers
Professional Video
DAC Current to Voltage Conversion
Baseband and Video Communications
Pin Diode Receivers
Active Filters/Integrators
PRODUCT DESCRIPTION
The AD8047 and AD8048 are very high speed and wide band-
width amplifiers. The AD8047 is unity gain stable. The
AD8048 is stable at gains of two or greater. The AD8047 and
AD8048, which utilize a voltage feedback architecture, meet the
requirements of many applications that previously depended on
current feedback amplifiers.
A proprietary circuit has produced an amplifier that combines
many of the best characteristics of both current feedback and
voltage feedback amplifiers. For the power (6.6 mA max) the
AD8047 and AD8048 exhibit fast and accurate pulse response
(30 ns to 0.01%) as well as extremely wide small signal and
large signal bandwidth and low distortion. The AD8047
achieves –54 dBc distortion at 20 MHz and 250 MHz small sig-
nal and 130 MHz large signal bandwidths.
FUNCTIONAL BLOCK DIAGRAM
8-Pin Plastic Mini-DIP (N), Cerdip (Q)
and SO (R) Packages
1
2
3
4
8
7
6
5
AD8047/48
NC
–INPUT
+INPUT
–V
S
NC
+V
S
OUTPUT
NC
(Top View)
NC = NO CONNECT
© Analog Devices, Inc., 1995
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Tel: 617/329-4700 Fax: 617/326-8703