a
FEATURES
Low Noise
0.9 nV/√Hz typ (1.2 nV/√Hz max) 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/ s Slew Rate
Excellent DC Precision
80 V max Input Offset Voltage
1.0 V/ C V
OS
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
ADC/DAC Buffers
PRODUCT DESCRIPTION
Ultralow Distortion,
Ultralow Noise Op Amp
AD797*
CONNECTION DIAGRAM
8-Pin Plastic Mini-DIP (N),
Cerdip (Q) and SOIC (R) Packages
OFFSET NULL
–IN
+IN
–V
S
1
2
3
4
AD797
8
7
6
DECOMPENSATION &
DISTORTION
NEUTRALIZATION
+V
S
OUTPUT
OFFSET NULL
TOP VIEW
5
necessary for preamps in microphones and mixing consoles.
Furthermore, the AD797’s excellent slew rate of 20 V/µs and
110 MHz gain bandwidth make it highly suitable for low fre-
quency ultrasound applications.
The AD797 is also useful in IR and Sonar Imaging applications
where the widest dynamic range is necessary. The low distor-
tion and 16-bit settling time of the AD797 make it ideal for
buffering the inputs to
Σ∆
ADCs or the outputs of high resolu-
tion DACs especially when they are used in critical applications
such as seismic detection and spectrum analyzers. Key features
such as a 50 mA output current drive and the specified power
supply voltage range of
±
5 to
±
15 volts make the AD797 an
excellent general purpose amplifier.
–90
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 at
audio bandwidths give the AD797 the wide dynamic range
5
Hz
4
–100
0.001
INPUT VOLTAGE NOISE – nV/
THD – dB
–110
0.0003
2
1
–120
MEASUREMENT
LIMIT
0.0001
0
10
100
1k
10k
100k
1M
10M
FREQUENCY – Hz
–130
100
300
1k
3k
10k
FREQUENCY – Hz
30k
100k
300k
AD797 Voltage Noise Spectral Density
*Patent
pending.
THD vs. Frequency
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
THD – %
3
AD797–SPECIFICATIONS
(@ T = +25 C and V =
A
S
15 V dc, unless otherwise noted)
AD797A/S
1
Min
Typ Max
25
50
0.2
0.25
0.5
100
120
1
1
1
1
14000
20
6
15
5
20000
110
450
8
280
20
800
130
120
130
120
50
1.7
0.9
1.0
2.0
±
11
±
2.5
±
12
±
11
±
2.5
30
±
12
±
3
±
13
±
13
±
3
80
50
–98
–120
–90
–110
±
11
±
2.5
±
12
±
11
±
2.5
30
80
125/180
1.0
1.5
3.0
400
600/700
2
2
2
2
14000
AD797B
Min Typ Max
10
30
0.2
40
60
0.6
Units
µV
µV
µV/°C
µA
µA
nA
nA
V/µV
V/µV
V/µV
V/µV
V/V
MHz
MHz
MHz
kHz
V/µs
ns
dB
dB
dB
dB
2.5
1.2
1.2
nV p-p
nV/√Hz
nV/√Hz
µV
rms
pA/√Hz
V
V
V
V
V
mA
mA
–90
dB
dB
Model
INPUT OFFSET VOLTAGE
Conditions
T
MIN
to T
MAX
V
S
±
5 V,
±
15 V
±
5 V,
±
15 V
±
5 V,
±
15 V
Offset Voltage Drift
INPUT BIAS CURRENT
T
MIN
to T
MAX
INPUT OFFSET CURRENT
T
MIN
to T
MAX
OPEN-LOOP GAIN
V
OUT
=
±
10 V
R
LOAD
= 2 kΩ
T
MIN
to T
MAX
R
LOAD
= 600
Ω
T
MIN
to T
MAX
@ 20 kHz
2
G = 1000
G = 1000
2
G = 10
V
O
= 20 V p-p,
R
LOAD
= 1 kΩ
R
LOAD
= 1 kΩ
10 V Step
V
CM
= CMVR
T
MIN
to T
MAX
V
S
=
±
5 V to
±
18 V
T
MIN
to T
MAX
f = 0. 1 Hz to 10 Hz
f = 10 Hz
f = 1 kHz
f = 10 Hz–1 MHz
f = 1 kHz
0.25 0.9
0.25 2.0
80
120
20
10
15
7
20000
110
450
8
280
20
800
130
120
130
120
50
1.7
0.9
1.0
2.0
±
12
±
3
±
13
±
13
±
3
80
50
–98
200
300
±
5 V,
±
15 V
±
15 V
DYNAMIC PERFORMANCE
Gain Bandwidth Product
–3 dB Bandwidth
Full Power Bandwidth
3
Slew Rate
Settling Time to 0.0015%
COMMON-MODE REJECTION
POWER SUPPLY REJECTION
INPUT VOLTAGE NOISE
±
15 V
±
15 V
±
15 V
±
15 V
±
15 V
±
15 V
±
5 V,
±
15 V
12.5
114
110
114
110
12.5
1200
120
114
120
114
1200
±
15 V
±
15 V
±
15 V
±
15 V
±
15 V
±
15 V
±
5 V
1.2
1.3
INPUT CURRENT NOISE
INPUT COMMON-MODE
VOLTAGE RANGE
OUTPUT VOLTAGE SWING
R
LOAD
= 2 kΩ
R
LOAD
= 600
Ω
R
LOAD
= 600
Ω
Short-Circuit Current
Output Current
4
TOTAL HARMONIC DISTORTION
R
LOAD
= 1 kΩ, C
N
= 50 pF
f = 250 kHz, 3 V rms
R
LOAD
= 1 kΩ
f = 20 kHz, 3 V rms
±
15 V
±
15 V
±
5 V
±
5 V,
±
15 V
±
5 V,
±
15 V
±
15 V
±
15 V
–120 –110
INPUT CHARACTERISTICS
Input Resistance (Differential)
Input Resistance (Common Mode)
Input Capacitance (Differential)
5
Input Capacitance (Common Mode)
OUTPUT RESISTANCE
POWER SUPPLY
Operating Range
Quiescent Current
A
V
= +1, f = 1 kHz
±
5
7.5
100
20
5
3
±
18
10.5
±
5
7.5
100
20
5
3
±
18
10.5
kΩ
MΩ
pF
pF
mΩ
V
mA
±
5 V,
±
15 V
8.2
8.2
NOTES
1
See standard military drawing for 883B specifications.
2
Specified using external decompensation capacitor, see Applications section.
3
Full Power Bandwidth = Slew Rate/2
π
V
PEAK
.
4
Output Current for |V
S
– V
OUT
| >4 V, A
OL
> 200 kΩ.
5
Differential input capacitance consists of 1.5 pF package capacitance and 18.5 pF from the input differential pair.
Specifications subject to change without notice.
–2–
REV. C
AD797
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
±
18 V
Internal Power Dissipation @ +25°C
2
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
±
V
S
Differential Input Voltage
3
. . . . . . . . . . . . . . . . . . . . . .
±
0.7 V
Output Short Circuit Duration . . . . . . . Indefinite Within max
Internal Power Dissipation
Storage Temperature Range (Cerdip) . . . . . . –65°C to +150°C
Storage Temperature Range (N, R Suffix) . . –65°C to +125°C
Operating Temperature Range
AD797A/B . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C
AD797S . . . . . . . . . . . . . . . . . . . . . . . . . . –55°C to +125°C
Lead Temperature Range (Soldering 60 sec) . . . . . . . +300°C
NOTES
1
Stresses above those listed under “Absolute Maximum Ratings” may cause
permanent damage to the device. This is a stress rating only, and functional
operation of the device at these or any other conditions above those indicated in the
operational section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
2
Internal Power Dissipation:
8-Pin SOIC = 0.9 Watts (T
A
–25°C)/θ
JA
8-Pin Plastic DIP and Cerdip = 1.3 Watts – (T
A
–25°C)/θ
JA
Thermal Characteristics
8-Pin Plastic DIP Package:
θ
JA
= 95°C/W
8-Pin Cerdip Package:
θ
JA
= 110°C/W
8-Pin Small Outline Package:
θ
JA
= 155°C/W
ABSOLUTE MAXIMUM RATINGS
1
3
The AD797’s inputs are protected by back-to-back diodes. To achieve low noise,
internal current limiting resistors are not incorporated into the design of this
amplifier. If the differential input voltage exceeds
±
0.7 V, the input current should
be limited to less than 25 mA by series protection resistors. Note, however, that this
will degrade the low noise performance of the device.
ESD SUSCEPTIBILITY
ESD (electrostatic discharge) sensitive device. Electrostatic
charges as high as 4000 volts, which readily accumulate on the
human body and on test equipment, can discharge without
detection. Although the AD797 features proprietary ESD pro-
tection circuitry, permanent damage may still occur on these
devices if they are subjected to high energy electrostatic dis-
charges. Therefore, proper ESD precautions are recommended
to avoid any performance degradation or loss of functionality.
ORDERING GUIDE
Model
AD797AN
AD797BN
AD797BR
AD797BR-REEL
AD797BR-REEL7
AD797AR
AD797AR-REEL
AD797AR-REEL7
5962-9313301MPA
Temperature
Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–55°C to +125°C
Package
Description
8-Pin Plastic DIP
8-Pin Plastic DIP
8-Pin Plastic SOIC
8-Pin Plastic SOIC
8-Pin Plastic SOIC
8-Pin Plastic SOIC
8-Pin Plastic SOIC
8-Pin Plastic SOIC
8-Pin Cerdip
Package
Option
N-8
N-8
SO-8
SO-8
SO-8
SO-8
SO-8
SO-8
Q-8
METALIZATION PHOTO
Contact factory for latest dimensions.
Dimensions shown in inches and (mm).
NOTE
The AD797 has double layer metal. Only one layer is shown here for clarity.
REV. C
–3–
AD797–Typical Characteristics
20
INPUT COMMON-MODE RANGE – ±Volts
15
10
5
0
0
5
10
SUPPLY VOLTAGE – ±Volts
15
20
VERTICAL SCALE – 0.01µV/DIV
HORIZONTAL SCALE – 5 sec/DIV
Figure 1. Common-Mode Voltage Range vs. Supply
20
Figure 4. 0.1 Hz to 10 Hz Noise
0.0
OUTPUT VOLTAGE SWING – ±Volts
15
INPUT BIAS CURRENT –
µA
15
20
–0.5
10
+V
OUT
–V
OUT
5
–1.0
–1.5
0
0
5
10
SUPPLY VOLTAGE – ±Volts
–2.0
–60
–40
–20
0
20
40
60
80
TEMPERATURE –
°C
100
120
140
Figure 2. Output Voltage Swing vs. Supply
30
OUTPUT VOLTAGE SWING – Volts p-p
Figure 5. Input Bias Current vs. Temperature
140
V
S
= ±15V
20
SHORT CIRCUIT CURRENT – mA
120
100
SOURCE CURRENT
SINK CURRENT
80
10
V
S
= ±5V
60
0
10
100
1k
LOAD RESISTANCE –
Ω
10k
40
–60
–40
–20
0
20
40
60
80
100
120
140
TEMPERATURE –
°C
Figure 3. Output Voltage Swing vs. Load Resistance
Figure 6. Short Circuit Current vs. Temperature
–4–
REV. C
AD797
11
QUIESCENT SUPPLY CURRENT – mA
140
POWER SUPPLY REJECTION – dB
10
+125°C
120
PSR
–SUPPLY
PSR
+SUPPLY
150
COMMON MODE REJECTION – dB
100
9
80
CMR
60
125
8
+25°C
100
7
–55°C
6
0
40
75
5
10
SUPPLY VOLTAGE – ±Volts
15
20
20
1
10
100
1k
10k
100k
FREQUENCY – Hz
50
1M
Figure 7. Quiescent Supply Current vs. Supply Voltage
Figure 10. Power Supply and Common-Mode Rejection
vs. Frequency
–60
R
L
= 600
Ω
G = +10
FREQ = 10kHz
NOISE BW = 100kHz
THD + NOISE – dB
12
FREQ = 1kHz
R
L
= 600Ω
OUTPUT VOLTAGE – Volts rms
G = +10
9
–80
6
V
S
= ±5V
–100
V
S
= ±15V
3
0
0
±5
±10
SUPPLY VOLTAGE – Volts
±15
±20
–120
0.01
0.1
1.0
10
OUTPUT LEVEL – Volts
Figure 8. Output Voltage vs. Supply for 0.01% Distortion
Figure 11. Total Harmonic Distortion (THD) + Noise vs.
Output Level
30
±15V
SUPPLIES
1.0
0.8
SETTLING TIME –
µs
0.0015%
0.6
0.01%
0.4
R
L
= 600
Ω
20
10
±5V
SUPPLIES
0.2
0.0
0
2
4
6
8
10
STEP SIZE – Volts
0
10k
100k
1M
10M
Figure 9. Settling Time vs. Step Size (
±
)
Figure 12. Large Signal Frequency Response
REV. C
–5–
电机控制
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