ANALOG DEVICES AD708 Service Manual
Ultralow Offset Voltage
www.BDTIC.com/ADI
FEATURES
Very high dc precision
30 μV maximum offset voltage
0.3 μV/°C maximum offset voltage drift
0.35 μV p-p maximum voltage noise (0.1 Hz to 10 Hz)
5 million V/V minimum open-loop gain
130 dB minimum CMRR
120 dB minimum PSRR
Matching characteristics
30 μV maximum offset voltage match
0.3 μV/°C maximum offset voltage drift match
130 dB minimum CMRR match
Available in 8-lead narrow body, PDIP, and
hermetic CERDIP and CERDIP/883B packages
GENERAL DESCRIPTION
The AD708 is a high precision, dual monolithic operational
amplifier. Each amplifier individually offers excellent dc
precision with maximum offset voltage and offset voltage drift
of any dual bipolar op amp.
The matching specifications are among the best available in any
d
ual op amp. In addition, the AD708 provides 5 V/V minimum open-loop gain and guaranteed maximum input voltage
noise of 350 nV p-p (0.1 Hz to 10 Hz). All dc specifications
show excellent stability over temperature, with offset voltage
drift typically 0.1 V/°C and input bias current drift of
25 pA/°C maximum.
The AD708 is available in four performance grades. The
AD708J is ra
0°C to 70°C and is available in a narrow body, PDIP. The
AD708A and AD708B are rated over the industrial temperature
range of −40°C to +85°C and are available in a CERDIP.
ted over the commercial temperature range of
Dual Op Amp
AD708
PIN CONFIGURATION
AD708
–IN A
+IN A
–V
S
1
2
3
4
–
A
+
TOP VIEW
(Not to Scale)
+V
8
S
OUTPUT B
7
–IN B
6
–
B
+
+IN B
5
05789-001
V/µV typical open-loop gain and 140 dB
OUTPUT A
Figure 1. PDIP (N) and CERDIP (Q) Packages
The AD708S is rated over the military temperature range of
o +125°C and is available in a CERDIP military version
−55°C t
processed to MIL-STD-883B.
PRODUCT HIGHLIGHTS
1. The combination of outstanding matching and individual
specifications make the AD708 ideal for constructing high
gain, precision instrumentation amplifiers.
2. The lo
3. The AD708 10
w offset voltage drift and low noise of the AD708
allow the designer to amplify very small signals without
sacrificing overall system performance.
common-mode rejection make it ideal for precision
applications.
Rev. C
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
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 www.analog.com
Fax: 781.461.3113 ©2006 Analog Devices, Inc. All rights reserved.
AD708
www.BDTIC.com/ADI
TABLE OF CONTENTS
Features .............................................................................................. 1
Theory of Operation ...................................................................... 10
Pin Configuration............................................................................. 1
General Description......................................................................... 1
Product Highlights........................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 5
ESD Caution.................................................................................. 5
Typical Performance Characteristics............................................. 6
Matching Characteristics............................................................. 9
REVISION HISTORY
1/06—Rev. B to Rev. C
Updated Format..................................................................Universal
moved TO-99 Package ..................................................Universal
Re
Deleted AD707 References................................................Universal
Deleted LT1002 Reference............................................................... 1
Deleted Figure 1................................................................................ 1
Deleted Metalization Photograph .................................................. 5
Moved Figure 25, Figure 26, and Figure 27
to Theory of Operation section .................................................... 10
Updated Outline Dimensions....................................................... 13
Changes to Ordering Guide.......................................................... 13
Crosstalk Performance .............................................................. 10
Operation with a Gain of −100................................................. 11
High Precision Programmable Gain Amplifier ..................... 11
Bridge Signal Conditioner......................................................... 12
Precision Absolute Value Circuit ............................................. 12
Selection of Passive Components............................................. 12
Outline Dimensions ....................................................................... 13
Ordering Guide .......................................................................... 13
2/91—Rev. A to Rev. B
Rev. C | Page 2 of 16
AD708
www.BDTIC.com/ADI
SPECIFICATIONS
@ 25°C and ±15 V dc, unless otherwise noted.
Table 1.
AD708J/AD708A AD708B AD708S
Parameter Conditions Min1Typ Max1Min1Typ Max1Min1Typ Max1Unit
INPUT OFFSET VOLTAGE
T
Drift 0.3 1.0 0.1 0.4 0.1 0.3 μV/°C
Long Term Stability 0.3 0.3 0.3 μV/month
INPUT BIAS CURRENT 1.0
T
Average Drift 15 40 10 25 10 30 pA/°C
OFFSET CURRENT VCM = 0 V 0.5
T
Average Drift 2 60 1 25 1 25 pA/°C
MATCHING CHARACTERISTICS3
Offset Voltage
T
Offset Voltage Drift 1.0 0.4
Input Bias Current
T
Common-Mode Rejection
T
Power Supply Rejection
T
Channel Separation 135 140 140 dB
INPUT VOLTAGE NOISE 0.1 Hz to 10 Hz 0.23 0.6 0.23 0.6 0.23
f = 10 Hz 10.3 18 10.3 12 10.3 12 nV/√Hz
f = 100 Hz 10.0 13.0 10.0 11.0 10.0 11 nV/√Hz
f = 1 kHz 9.6 11.0 9.6 11.0 9.6 11 nV/√Hz
INPUT CURRENT NOISE 0.1 Hz to 10 Hz 14 35 14 35 14 35 pA p-p
f = 10 Hz 0.32 0.9 0.32 0.8 0.32 0.8 pA/√Hz
f = 100 Hz 0.14 0.27 0.14 0.23 0.14 0.23 pA/√Hz
f = 1 kHz 0.12 0.18 0.12 0.17 0.12 0.17 pA/√Hz
COMMON-MODE REJECTION RATIO VCM = ±13 V
T
OPEN-LOOP GAIN VO = ±10 V
R
T
POWER SUPPLY REJECTION RATIO VS = ±3 V to ±18 V
T
FREQUENCY RESPONSE
Closed-Loop Bandwidth 0.5 0.9 0.5 0.9 0.5 0.9 MHz
Slew Rate 0.15 0.3 0.15 0.3 0.15 0.3 V/μs
INPUT RESISTANCE
Differential 60 200 200 MΩ
Common Mode 200 400 400 GΩ
2
30
MIN
to T
MAX
50 150 15 65 15 50 μV
100
2.5
MIN
to T
MAX
2.0 4.0 1.0
2.0
MIN
to T
MAX
2.0 4.0 0.2 1.5 0.2
80
to T
MIN
150 75
MAX
4.0
MIN
MIN
MIN
MIN
LOAD
MIN
MIN
to T
MAX
to T
MAX
to T
MAX
to T
MAX
≥ 2 kΩ
to T
MAX
to T
MAX
5.0 2.0
120
140
110 130
110
110 120
120
140
120 140 130 140
3
10
3 10 5 10
110
130
110 130 120 130
5
0.5
0.1
50
130
120
130
5
120
50
1.0
2.0
1.0
1.0
140
140
10
130
5
0.5
1.0
0.1
30
1
4
1
1.5
30
50
0.3
1.0
2.0
140 dB
130
dB
130
dB
120
dB
120
0.35
140 dB
130
140 dB
130
10 V/μV
4
7 V/μV
4
130 dB
120
130 dB
120
μV
nA
nA
nA
nA
μV
μV
μV/°C
nA
nA
μV p-p
Rev. C | Page 3 of 16
AD708
www.BDTIC.com/ADI
AD708J/AD708A AD708B AD708S
Parameter Conditions Min1Typ Max1Min1Typ Max1Min1Typ Max1Unit
OUTPUT VOLTAGE R
R
R
T
OPEN-LOOP OUTPUT RESISTANCE 60 60 60 Ω
POWER SUPPLY
Quiescent Current 4.5 5.5 4.5 5.5 4.5 5.5 mA
Power Consumption VS = ±15 V 135
V
Operating Range ±3 ±18 ±3 ±18 ±3 ±18 V
1
All min and max specifications are guaranteed. Specifications in boldface are tested on all production units at final electrical test. Results from those tests are used to
calculate outgoing quality levels.
2
Input offset voltage specifications are guaranteed after five minutes of operation at TA = 25°C.
3
Matching is defined as the difference between parameters of the two amplifiers.
≥ 10 kΩ
LOAD
≥ 2 kΩ
LOAD
≥ 1 kΩ
LOAD
to T
MIN
MAX
= ±3 V 12
S
13.5
12.5
12.0
12.0 13.0 12.0 13.0
14
13.0
12.5
165
18
14.0
13.5
13.0
12.5
12.5
12.0
135
12
165
18
14 ±V
13.5
13 ±V
12.5
12.5 ±V
12.0
13 ±V
12.0
135
12
165
18
mW
mW
Rev. C | Page 4 of 16
AD708
www.BDTIC.com/ADI
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
Supply Voltage ±22 V
Internal Power Dissipation
Input Voltage
Output Short-Circuit Duration Indefinite
Differential Input Voltage +VS and −V
Storage Temperature Range (Q) −65°C to +150°C
Storage Temperature Range (N) −65°C to +125°C
Lead Temperature (Soldering 60 sec) 300°C
1
Thermal Characteristics
8-lead PDIP: θ
8-lead CERDIP: θJC = 30°C/W, θJA = 110°C/W
2
For supply voltages less than ±22 V, the absolute maximum input voltage is
equal to the supply voltage.
2
= 33°C/W, θJA = 100°C/W
JC
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
1
±V
S
S
Stresses above those listed under Absolute Maximum Ratings
ma
y cause permanent damage to the device. This is a stress
rating only; 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.
Rev. C | Page 5 of 16
Loading...