Analog Devices AD642 Datasheet
Precision, Low Cost
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FEATURES
Matched Offset Voltage
Matched Offset Voltage Over Temperature
Matched Bias Current
Crosstalk: –124 dB @ 1 kHz
Low Bias Current: 35 pA max Warmed Up
Low Offset Voltage: 500 mV max
Low Input Voltage Noise: 2 mV p-p
High Open Loop Gain
Low Quiescent Current: 2.8 mA max
Low Total Harmonic Distortion
Standard Dual Amplifier Pin Out
Available in Hermetic Metal Can Package and Chip Form
MIL-STD-883B Processing Available
Single Version Available: AD542
PRODUCT DESCRIPTION
The AD642 is a pair of matched high speed monolithic BiFET
operational amplifier fabricated with the most advanced bipolar,
JFET and laser trimming technologies. The AD642 offers
matched bias currents that are significantly lower than currently
available monolithic dual FET input operational amplifiers:
35 pA max matched to 25 pA for the AD642K and L; 75 pA
max, matched to 35 pA for the AD642J and S. In addition, the
offset voltage is laser trimmed to less than 0.5 mV and matched
to 0.25 mV for the AD642L, 1.0 mV and matched to 0.5 mV for
the AD642K, utilizing Analog’s laser-wafer trimming (LWT)
process.
The tight matching and temperature tracking between the
operational amplifiers is achieved by ion-implanted JFETs and
laser-wafer trimming. Ion-implantation permits the fabrication of
precision, matched JFETs on a monolithic bipolar chip. The
optimizes the process to product matched bias currents which
have lower initial bias currents than other popular BiFET op
amps. Laser-wafer trimming each amplifier’s input offset voltage
assures tight initial match and combined with superior IC
processing guarantees offset voltage tracking over the temperature range.
The AD642 is recommended for applications in which excellent
ac and dc performance is required. The matched amplifiers
provide a low-cost solution for true instrumentation amplifiers,
log ratio amplifiers, and output amplifiers for four quadrant
multiplying D/A converters such as the AD7541.
Dual BiFET Op Amp
AD642
PIN CONFIGURATION
The AD642 is available in four versions: the ‘‘J’’, ‘‘K’’ and ‘‘L,’’
all specified over the 0°C to +70°C temperature range and one
version, ‘‘S,’’ over the –55°C to +125°C extended operating
temperature range. All devices are packaged in the hermeticallysealed, TO-99 metal can or available in chip form.
PRODUCT HIGHLIGHTS
1. The AD642 has tight matching specifications to ensure high
performance, eliminating the need to match individual
devices.
2. Analog Devices, unlike some manufacturers, specifies each
device for the maximum bias current at either input in the
warmed-up condition, thus assuring the user that the AD642
will meet its published specifications in actual use.
3. Laser-wafer-trimming reduces offset voltage to as low as
0.5 mV max and matched side to side to 0.25 mV
(AD642L), thus eliminating the need for external nulling.
4. Low voltage noise (2 µV, p-p), and high open loop gain
enhance the AD642’s performance as a precision op amp.
5. The standard dual amplifier pin out allows the AD642 to
replace lower performance duals without redesign.
6. The AD642 is available in chip form.
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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
AD642–SPECIFICATIONS
(@ + 25°C, and VS = ±15 V dc)
Model Min Typ Max Min Typ Max Min Typ Max Min Typ Max Unit
AD642J AD642K AD642L AD642S
OPEN LOOP GAIN
= ±10 V, RL ≥ 2 kΩ 100,000 250,000 250,000 250,000 V/V
V
O
T
to T
MIN
OUTPUT CHARACTERISTICS
Voltage @ R
Voltage @ R
Short Circuit Current 25 25 25 25 mA
, RL = 2 kΩ 100,000 250,000 250,000 100,000 V/V
MAX
= 2 kΩ, T
L
= 10 kΩ, T
L
MIN
MIN
to T
to T
MAX
MAX
±
10 ±12
±
12 ±13
±
10 ±12
±
12 ±13
±
10 ±12
±
12 ±13
±
10 ±12 V
±
12 ±13 V
FREQUENCY RESPONSE
Unity Gain Small Signal 1.0 1.0 1.0 1.0 MHz
Full Power Response 50 50 50 50 kHz
Slew Rate, Unity Gain 2.0 3.0 2.0 3.0 2.0 3.0 2.0 3.0 V/µs
INPUT OFFSET VOLTAGE
1
Initial Offset 2.0 1.0 0.5 1.0 mV
Input Offset Voltage T
Input Offset Voltage vs. Supply,
T
to T
MIN
MAX
INPUT BIAS CURRENT
Either Input 10 75 10 35 10 35 10 35 pA
Offset Current 5 2 2 2
MATCHING CHARACTERISTICS
MIN
2
to T
MAX
3
3.5 2.0 1.0 3.5 mV
200 100 100 100 µV/V
Input Offset Voltage 1.0 0.5 0.25 0.5 mV
Input Offset Voltage T
Input Bias Current 35 25 25 35 pA
MIN
to T
MAX
3.5 2.0 1.0 3.5 mV
Crosstalk –124 –124 –124 –124 dB
INPUT IMPEDANCE
Differential 10
Common Mode 1012i610
INPUT VOLTAGE RANGE
Differential
Common Mode
4
±
10 ±12
12
i610
±20 ±20 ±20 ±20 V
±
10 ±12
12
i610
12
i610
±
10 ±12
12
i610
12
i610
±
10 ±12 V
12
i6MΩipF
12
i6MΩipF
Common-Mode Rejection 76 80 80 80 dB
INPUT NOISE
Voltage 0.1 Hz to 10 Hz 2 2 2 2 µV p-p
f = 10 Hz 70 70 70 70 nV/√
f = 100 Hz 45 45 45 45 nV/√
f = 1 kHz 30 30 30 30 nV/√
f = 10 kHz 25 25 25 25 nV/√Hz
Hz
Hz
Hz
POWER SUPPLY
Rated Performance ± 15 ± 15 ±15 ±15 V
Operating ± 5 ±18 ± 5 ±15 ± 5 ±15 ±5 ± 15 V
Quiescent Current 2.8 2.8 2.8 2.8 mA
TRANSISTOR COUNT 58 58 58 58
PACKAGE OPTION
TO-99 Style (H-08B) AD642JH AD642KH AD642LH AD642SH
NOTES
1
Input Offset Voltage specifications are guaranteed after 5 minutes of operation at TA = +25°C.
2
Bias Current specifications are guaranteed at maximum at either input after 5 minutes of operation at T
every 10°C.
3
Matching is defined as ther difference between parameters of the two amplifiers.
4
Defined as the maximum safe voltage between inputs, such that neither exceeds ±10 V from ground.
Specifications subject to change without notice.
Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min
= +25°C. For higher temperatures, the current doublers
A
and max specifications are guaranteed, although only those shown in boldface are tested on all production units.
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
TO-99
REFERENCE PLANE
0.750 (19.05)
0.050
(1.27)
MAX
0.500 (12.70)
0.250 (6.35)
MIN
0.019 (0.48)
0.016 (0.41)
0.021 (0.53)
0.016 (0.41)
BASE & SEATING PLANE
0.200
(5.08)
BSC
0.335 (8.51)
0.305 (7.75)
0.370 (9.40)
0.335 (8.51)
0.185 (4.70)
0.165 (4.19)
0.040 (1.02) MAX
0.045 (1.14)
0.010 (0.25)
0.100
(2.54)
BSC
0.100
(2.54)
BSC
4
3
2
5
1
0.034 (0.86)
0.027 (0.69)
6
8
BSC
45
0.160 (4.06)
0.110 (2.79)
7
°
0.045 (1.14)
0.027 (0.69)
–2–
METALIZATION PHOTOGRAPHIC
Contact factory for latest dimensions.
Dimensions shown in inches and (mm).
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