REV. D
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a
AD745
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2002
Ultralow Noise,
High Speed, BiFET Op Amp
CONNECTION DIAGRAM
FEATURES
ULTRALOW NOISE PERFORMANCE
2.9 nV/冑 Hz at 10 kHz
0.38 V p-p, 0.1 Hz to 10 Hz
6.9 fA/冑Hz Current Noise at 1 kHz
EXCELLENT AC PERFORMANCE
12.5 V/s Slew Rate
20 MHz Gain Bandwidth Product
THD = 0.0002% @ 1 kHz
Internally Compensated for Gains of +5 (or –4) or
Greater
EXCELLENT DC PERFORMANCE
0.5 mV Max Offset Voltage
250 pA Max Input Bias Current
2000 V/mV Min Open Loop Gain
Available in Tape and Reel in Accordance with
EIA-481A Standard
APPLICATIONS
Sonar
Photodiode and IR Detector Amplifiers
Accelerometers
Low Noise Preamplifiers
High Performance Audio
PRODUCT DESCRIPTION
The AD745 is an ultralow noise, high-speed, FET input opera-
tional amplifier. It offers both the ultralow voltage noise and
high speed generally associated with bipolar input op amps and
the very low input currents of FET input devices. Its 20 MHz
bandwidth and 12.5 V/µs slew rate makes the AD745 an ideal
SOURCE RESISTANCE –
1000
100
INPUT NOISE VOLTAGE – nV/ Hz
100
10
1
1k 10k 100k 1M 10M
R
SOURCE
R
SOURCE
E
O
OP37 AND
RESISTOR
AD745 AND
RESISTOR
AD745 AND RESISTOR
OR
OP37 AND RESISTOR
RESISTOR NOISE ONLY
Figure 1.
amplifier for high-speed applications demanding low noise and
high dc precision. Furthermore, the AD745 does not exhibit an
output phase reversal.
The AD745 also has excellent dc performance with 250 pA
maximum input bias current and 0.5 mV maximum offset voltage.
The internal compensation of the AD745 is optimized for higher
gains, providing a much higher bandwidth and a faster slew
rate. This makes the AD745 especially useful as a preamplifier
where low level signals require an amplifier that provides both
high amplification and wide bandwidth at these higher gains.
The AD745 is available in two performance grades. The AD745J
and AD745K are rated over the commercial temperature range
of 0°C to 70°C, and are available in the 16-lead SOIC package.
FREQUENCY – Hz
120
100
OPEN-LOOP GAIN – dB
100
80
60
40
20
0
–20
1k 10k 100k 1M 10M 100M
120
100
80
60
40
20
0
–20
PHASE MARGIN – Degrees
GAIN
PHASE
Figure 2.
16-Lead SOIC (R) Package
