Ultralow Distortion,
Ultralow Noise Op Amp
AD797
Data Sheet
FEATURES
Low noise
0.9 nV/√Hz typical (1.2 nV/√Hz maximum) input voltage
noise at 1 kHz
50 nV p-p input voltage noise, 0.1 Hz to 10 Hz
Low distortion
−120 dB total harmonic distortion at 20 kHz
Excellent ac characteristics
800 ns settling time to 16 bits (10 V step)
110 MHz gain bandwidth (G = 1000)
8 MHz bandwidth (G = 10)
280 kHz full power bandwidth at 20 V p-p
20 V/μs slew rate
Excellent dc precision
80 μV maximum input offset voltage
1.0 μV/°C VOS drift
Specified for ±5 V and ±15 V power supplies
High output drive current of 50 mA
APPLICATIONS
Professional audio preamplifiers
IR, CCD, and sonar imaging systems
Spectrum analyzers
Ultrasound preamplifiers
Seismic detectors
Σ-Δ ADC/DAC buffers
GENERAL DESCRIPTION
The AD797 is a very low noise, low distortion operational amplifier
ideal for use as a preamplifier. The low noise of 0.9 nV/√Hz and
low total harmonic distortion of −120 dB in audio bandwidths
give the AD797 the wide dynamic range necessary for preamps
in microphones and mixing consoles.
Furthermore, the AD797 has an excellent slew rate of 20 V/μs
and a 110 MHz gain bandwidth, which makes it highly suitable
for low frequency ultrasound applications.
The AD797 is also useful in infrared (IR) and sonar imaging
applications, where the widest dynamic range is necessary. The
low distortion and 16-bit settling time of the AD797 make it
ideal for buffering the inputs to Σ-Δ ADCs or the outputs of
high resolution DACs, especially when the device is used in
critical applications such as seismic detection or in spectrum
analyzers. Key features such as a 50 mA output current drive
and the specified power supply voltage range of ±5 V to ±15 V
make the AD797 an excellent general-purpose amplifier.
4
3
2
1
0
10
100
1k
10k
100k
10M
1M
FREQUENCY (Hz)
00846-002
INPUT VOLTAGE NOISE (nV/√Hz)
5
Figure 1. AD797 Voltage Noise Spectral Density
Table 1. Low Noise Op Amps
Voltage Noise
Single
Dual
Quad
Rev. J
0.9 nV
AD797
1.1 nV
AD8597
AD8599
1.8 nV
ADA4004-1
ADA4004-2
ADA4004-4
2.8 nV
AD8675/ADA4075-2
AD8676
3.2 nV
OP27
OP270
OP470
3.8 nV
AD8671
AD8672
AD8674
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