Low Power, Low Noise
Precision FET Op Amp
AD795
FEATURES
Low power replacement for Burr-Brown
OPA111, OPA121 op amps
Low noise
3.3 μV p-p maximum, 0.1 Hz to 10 Hz
11 nV/√Hz maximum at 10 kHz
0.6 fA/√Hz at 1 kHz
High dc accuracy
500 μV maximum offset voltage
10 μV/°C maximum drift
2 pA maximum input bias current
Low power: 1.5 mA maximum supply current
CONNECTION DIAGRAM
NC
1
–IN
2
+IN
3
–V
S 4
8
7
6
NC
+V
S
OUTPUT
00845-001
AD795
5
NC
NC = NO CONNECT
Figure 1. 8-Lead SOIC (R) Package
APPLICATIONS
Low noise photodiode preamps
CT scanners
Precision l-to-V converters
GENERAL DESCRIPTION
The AD795 is a low noise, precision, FET input operational
amplifier. It offers both the low voltage noise and low offset drift
of a bipolar input op amp and the very low bias current of a FET-
input device. The 10
14
Ω common-mode impedance insures
that input bias current is essentially independent of common-
mode voltage and supply voltage variations.
The AD795 has both excellent dc performance and a guaranteed
and tested maximum input voltage noise. It features 2 pA
maximum input bias current and 500 μV maximum offset
voltage, along with low supply current of 1.5 mA maximum.
1k
Furthermore, the AD795 features a guaranteed low input noise
of 3.3 μV p-p (0.1 Hz to 10 Hz) and a 11 nV/√Hz maximum
noise level at 10 kHz. The AD795 has a fully specified and
tested input offset voltage drift of only 10 μV/°C maximum.
The AD795 is useful for many high input impedance, low noise
applications. The AD795 is rated over the commercial tempera-
ture range of 0°C to +70°C.
The AD795 is available in an 8-lead SOIC package.
50
SAMPLE SIZE = 570
VOLTAGE NOISE SPECTRAL DENSITY (nV/ Hz)
40
PERCENTAGE OF UNITS
30
100
20
10
10
–4
100
1k
FREQUENCY (Hz)
10k
00845-002
1
10
–3
–2
–1
0
1
2
3
INPUT OFFSET VOLTAGE DRIFT (µV/°C)
4
5
Figure 3. Typical Distribution of Average Input Offset Voltage Drift
Figure 2. Voltage Noise Spectral Density
Rev. C
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113 ©2002–2009 Analog Devices, Inc. All rights reserved.
00845-003
0
–5
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