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11023701 UNPDF
a
Ultralow Distortion,
Ultralow Noise Op Amp
AD797*
FEATURES
Low Noise
0.9 nV/
Ö
Hz typ (1.2 nV/
Ö
Hz max) Input Voltage
CONNECTION DIAGRAM
8-Pin Plastic Mini-DIP (N),
Cerdip (Q) and SOIC (R) Packages
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/
OFFSET NULL
1
AD797
8
DECOMPENSATION &
DISTORTION
NEUTRALIZATION
–IN
+IN
2
7
+V S
3
6
OUTPUT
–V S
4
TOP VIEW
5
OFFSET NULL
s Slew Rate
Excellent DC Precision
80
m
m
V max Input Offset Voltage
C V OS Drift
Specified for
m
V/
8
15 V Power Supplies
High Output Drive Current of 50 mA
6
5 V and
6
APPLICATIONS
Professional Audio Preamplifiers
IR, CCD, and Sonar Imaging Systems
Spectrum Analyzers
Ultrasound Preamplifiers
Seismic Detectors
SD
necessary for preamps in microphones and mixing consoles.
Furthermore, the AD797’s excellent slew rate of 20 V/ms 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 SD 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.
PRODUCT DESCRIPTION
The AD797 is a very low noise, low distortion operational
amplifier id e al for use as a preamplifier. The low noise of
0.9 nV/
5
–90
4
–100
0.001
3
–110
0.0003
2
1
–120
0.0001
MEASUREMENT
LIMIT
0
–130
10
100
1k
10k
100k
1M
10M
100
300
1k
3k
10k
30k
100k
300k
FREQUENCY – Hz
FREQUENCY – Hz
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
1.0
ADC/DAC Buffers
Hz and low total harmonic distortion of –120 dB at
audio bandwidths give the AD797 the wide dynamic range
Ö
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AD797–SPECIFICATIONS (@ T A = +25 8 C and V S = 6 15 V dc, unless otherwise noted)
AD797A/S 1
AD797B
Model
Conditions
V S
Min
Typ Max
Min Typ Max Units
INPUT OFFSET VOLTAGE
± 5 V, ± 15 V
25
80
10
40
mV
T MIN to T MAX
50
125/180
30
60
m
V
Offset Voltage Drift
± 5 V, ± 15 V
0.2
1.0
0.2 0.6
mV/°C
INPUT BIAS CURRENT
± 5 V, ± 15 V
0.25 1.5
0.25 0.9
mA
T MIN to T MAX
0.5
3.0
0.25 2.0
m
A
INPUT OFFSET CURRENT
± 5 V, ± 15 V
100 400
80
200 nA
T MIN to T MAX
120 600/700
120 300 nA
OPEN-LOOP GAIN
V OUT =
±
10 V
±
15 V
R LOAD = 2 kW
1
20
2
20
V/mV
T MIN to T MAX
1
6
2
10
V/
m
V
R LOAD = 600 W
1
15
2
15
V/mV
T MIN to T MAX
1
5
2
7
V/
m
V
@ 20 kHz 2
14000 20000
14000 20000
V/V
DYNAMIC PERFORMANCE
Gain Bandwidth Product
G = 1000
±
15 V
110
110
MHz
G = 1000 2
±
15 V
450
450
MHz
–3 dB Bandwidth
G = 10
±
15 V
8
8
MHz
Full Power Bandwidth 3
V O = 20 V p-p,
R LOAD = 1 k
W
±
15 V
280
280
kHz
Slew Rate
R LOAD = 1 k
W
±
15 V
12.5
20
12.5 20
V/
m
s
Settling Time to 0.0015%
10 V Step
±
15 V
800 1200
800 1200 ns
COMMON-MODE REJECTION
V CM = CMVR
± 5 V, ± 15 V 114
130
120 130
dB
T MIN to T MAX
110
120
114 120
dB
POWER SUPPLY REJECTION
V S =
±
5 V to
±
18 V
114
130
120 130
dB
T MIN to T MAX
110
120
114 120
dB
INPUT VOLTAGE NOISE
f = 0. 1 Hz to 10 Hz
±
15 V
50
50
nV p-p
f = 10 Hz
± 15 V
1.7
1.7 2.5
nV/ÖHz
f = 1 kHz
±
15 V
0.9
1.2
0.9 1.2
nV/
Ö
Hz
f = 10 Hz–1 MHz
± 15 V
1.0
1.3
1.0 1.2
mV rms
INPUT CURRENT NOISE
f = 1 kHz
± 15 V
2.0
2.0
pA/ÖHz
INPUT COMMON-MODE
± 15 V
± 11
± 12
± 11
± 12
V
VOLTAGE RANGE
± 5 V
± 2.5
± 3
± 2.5
± 3
V
OUTPUT VOLTAGE SWING
R LOAD = 2 kW
± 15 V
± 12
± 13
± 12
± 13
V
R LOAD = 600
W
±
15 V
±
11
±
13
±
11
±
13
V
R LOAD = 600 W
± 5 V
± 2.5
± 3
± 2.5
± 3
V
Short-Circuit Current
±
5 V,
±
15 V
80
80
mA
Output Current 4
± 5 V, ± 15 V 30
50
30
50
mA
TOTAL HARMONIC DISTORTION R LOAD = 1 kW, C N = 50 pF
± 15 V
–98 –90
–98 –90 dB
f = 250 kHz, 3 V rms
R LOAD = 1 kW
± 15 V
–120 –110
–120 –110 dB
f = 20 kHz, 3 V rms
INPUT CHARACTERISTICS
Input Resistance (Differential)
7.5
7.5
k
W
Input Resistance (Common Mode)
100
100
MW
Input Capacitance (Differential) 5
20
20
pF
Input Capacitance (Common Mode)
5
5
pF
OUTPUT RESISTANCE
A V = +1, f = 1 kHz
3
3
mW
POWER SUPPLY
Operating Range
±
5
±
18
±
5
±
18 V
Quiescent Current
± 5 V, ± 15 V
8.2
10.5
8.2 10.5 mA
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
p
.
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.
W
–2–
REV. C
V PEAK .
4 Output Current for |V S – V OUT | >4 V, A OL > 200 k
11023701.006.png 11023701.007.png
AD797
ABSOLUTE MAXIMUM RATINGS 1
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
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
±
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
Temperature
Package
Package
Model
Range
Description
Option
q JA
8-Pin Plastic DIP and Cerdip = 1.3 Watts – (T A –25
°
C)/
AD797AN
–40°C to +85°C
8-Pin Plastic DIP
N-8
C)/
q JA
AD797BN
–40°C to +85°C
8-Pin Plastic DIP
N-8
Thermal Characteristics
8-Pin Plastic DIP Package:
q JA = 95
C/W
AD797BR
–40°C to +85°C
8-Pin Plastic SOIC
SO-8
AD797BR-REEL
–40°C to +85°C
8-Pin Plastic SOIC
SO-8
8-Pin Cerdip Package:
q JA = 110
°
C/W
AD797BR-REEL7 –40°C to +85°C
8-Pin Plastic SOIC
SO-8
8-Pin Small Outline Package:
q JA = 155
°
C/W
AD797AR
–40°C to +85°C
8-Pin Plastic SOIC
SO-8
AD797AR-REEL
–40°C to +85°C
8-Pin Plastic SOIC
SO-8
AD797AR-REEL7 –40°C to +85°C
8-Pin Plastic SOIC
SO-8
5962-9313301MPA –55°C to +125°C 8-Pin Cerdip
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–
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.
°
°
11023701.008.png
AD797–Typical Characteristics
20
15
10
5
0
0
5
10
15
20
HORIZONTAL SCALE – 5 sec/DIV
SUPPLY VOLTAGE – ±Volts
Figure 1. Common-Mode Voltage Range vs. Supply
Figure 4. 0.1 Hz to 10 Hz Noise
20
0.0
15
–0.5
10
–1.0
–V OUT
+V OUT
5
–1.5
0
–2.0
0
5
10
15
20
–60
–40
–20
0
20
40
60
80
100 120
140
SUPPLY VOLTAGE – ±Volts
C
Figure 5. Input Bias Current vs. Temperature
TEMPERATURE –
°
Figure 2. Output Voltage Swing vs. Supply
30
140
V = ±15V
S
120
20
100
SINK CURRENT
SOURCE CURRENT
80
10
V = ±5V
S
60
0
40
–60
–40
–20
0
20
40
60
100
120
140
10
100
1k
10k
80
W
Figure 3. Output Voltage Swing vs. Load Resistance
LOAD RESISTANCE –
TEMPERATURE – ° C
Figure 6. Short Circuit Current vs. Temperature
–4–
REV. C
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AD797
11
140
10
+125°C
120
PSR
+SUPPLY
PSR
–SUPPLY
100
150
9
80
125
+25°C
8
CMR
60
100
7
–55°C
40
75
6
20
50
0
5
10
SUPPLY VOLTAGE – ±Volts
15
20
1
10
100
1k
10k
100k
1M
FREQUENCY – Hz
Figure 7. Quiescent Supply Current vs. Supply Voltage
Figure 10. Power Supply and Common-Mode Rejection
vs. Frequency
–60
12
R L = 600
G = +10
FREQ = 10kHz
NOISE BW = 100kHz
W
FREQ = 1kHz
R L = 600 W
G = +10
9
–80
6
V S = ±5V
–100
3
V S
= ±15V
0
–120
0.01
0
±5
±10
±15
±20
0.1
1.0
10
SUPPLY VOLTAGE – Volts
OUTPUT LEVEL – Volts
Figure 8. Output Voltage vs. Supply for 0.01% Distortion
Figure 11. Total Harmonic Distortion (THD) + Noise vs.
Output Level
1.0
30
± 15V SUPPLIES
0.8
R L = 600
W
0.0015%
20
0.6
0.01%
0.4
10
± 5V SUPPLIES
0.2
0.0
0
0
2
4
6
8
10
10k
100k
1M
10M
STEP SIZE – Volts
Figure 9. Settling Time vs. Step Size ( ± )
Figure 12. Large Signal Frequency Response
REV. C
–5–
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