REV. C
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otherwise under any patent or patent rights of Analog Devices.
a
Wideband,
Fast Settling Op Amp
AD840
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700 Fax: 617/326-8703
CONNECTION DIAGRAMS
FEATURES
Wideband AC Performance
Gain Bandwidth Product: 400 MHz (Gain ≥ 10)
Fast Settling: 100 ns to 0.01% for a 10 V Step
Slew Rate: 400 V/ms
Stable at Gains of 10 or Greater
Full Power Bandwidth: 6.4 MHz for 20 V p-p into a
500 V Load
Precision DC Performance
Input Offset Voltage: 0.3 mV max
Input Offset Drift: 3 mV/8C typ
Input Voltage Noise: 4 nV/√
Hz
Open-Loop Gain: 130 V/mV into a 1 kV Load
Output Current: 50 mA min
Supply Current: 12 mA max
APPLICATIONS
Video and Pulse Amplifiers
DAC and ADC Buffers
Line Drivers
Available in 14-Pin Plastic DIP, Hermetic Cerdip
and 20-Pin LCC Packages and in Chip Form
MIL-STD-883B Processing Available
PRODUCT DESCRIPTION
The AD840 is a member of the Analog Devices’ family of wide
bandwidth operational amplifiers. This high speed/high precision
family includes, among others, the AD841, which is unity-
gain stable, and the AD842, which is stable at a gain of two or
greater and has 100 mA minimum output current drive. These
devices are fabricated using Analog Devices’ junction isolated
complementary bipolar (CB) process. This process permits a
combination of dc precision and wideband ac performance
previously unobtainable in a monolithic op amp. In addition
to its 400 MHz gain bandwidth product, the AD840 offers
extremely fast settling characteristics, typically settling to within
0.01% of final value in 100 ns for a 10 volt step.
The AD840 remains stable over its full operating temperature
range at closed-loop gains of 10 or greater. It also offers a low
quiescent current of 12 mA maximum, a minimum output
current drive capability of 50 mA, a low input voltage noise of
4 nV/√
Hz and a low input offset voltage of 0.3 mV maximum
(AD840K).
The 400 V/µs slew rate of the AD840, along with its 400 MHz
gain bandwidth, ensures excellent performance in video and
pulse amplifier applications. This amplifier is ideally suited for
use in high frequency signal conditioning circuits and wide
bandwidth active filters. The extremely rapid settling time of the
AD840 makes it the preferred choice for data acquisition appli-
cations which require 12-bit accuracy. The AD840 is also ap-
propriate for other applications such as high speed DAC and
ADC buffer amplifiers and other wide bandwidth circuitry.
APPLICATION HIGHLIGHTS
1. The high slew rate and fast settling time of the AD840 make
it ideal for DAC and ADC buffers, line drivers and all types
of video instrumentation circuitry.
2. The AD840 is truly a precision amplifier. It offers 12-bit
accuracy to 0.01% or better and wide bandwidth, perfor-
mance previously available only in hybrids.
3. The AD840’s thermally balanced layout and the high speed
of the CB process allow the AD840 to settle to 0.01% in
100 ns without the long “tails” that occur with other fast op
amps.
4. Laser wafer trimming reduces the input offset voltage to
0.3 mV max on the K grade, thus eliminating the need for
external offset nulling in many applications. Offset null pins
are provided for additional versatility.
5. Full differential inputs provide outstanding performance
in all standard high frequency op amp applications where
circuit gain will be 10 or greater.
6. The AD840 is an enhanced replacement for the HA2540.
Plastic DIP (N) Package
and
Cerdip (Q) Package
LCC (E) Package
