Low Power, Low Noise
Precision FET Op Amp
AD795
FEATURES
CONNECTION DIAGRAM
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
NC
–IN
+IN
1
2
3
4
8
7
6
5
NC
+V
S
OUTPUT
NC
–V
S
AD795
NC = NO CONNECT
Figure 1. 8-Lead SOIC (R) Package
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
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 1014 Ω common-mode impedance insures
that input bias current is essentially independent of common-
mode voltage and supply voltage variations.
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 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
The AD795 is available in an 8-lead SOIC package.
50
SAMPLE SIZE = 570
40
30
20
10
100
10
1
0
–5
–4
–3
–2
–1
0
1
2
3
4
5
INPUT OFFSET VOLTAGE DRIFT (µV/°C)
10
100
FREQUENCY (Hz)
1k
10k
Figure 3. Typical Distribution of Average Input Offset Voltage Drift
Figure 2. Voltage Noise Spectral Density
Rev. C
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