a
FEATURES
High DC Precision
75 V max Offset Voltage
1 V/ C max Offset Voltage Drift
150 pA max Input Bias Current
0.2 pA/ C typical I
B
Drift
Low Noise
0.5 V p-p typical Noise, 0.1 Hz to 10 Hz
Low Power
600 A max Supply Current per Amplifier
Chips & MIL-STD-883B Processing Available
Available in Tape and Reel in Accordance
with EIA-481A Standard
Single Version: AD705, Dual Version: AD706
PRIMARY APPLICATIONS
Industrial/Process Controls
Weigh Scales
ECG/EKG Instrumentation
Low Frequency Active Filters
Quad Picoampere Input Current
Bipolar Op Amp
AD704
CONNECTION DIAGRAMS
14-Pin Plastic DIP (N)
14-Pin Cerdip (Q) Packages
OUTPUT
–IN
+ IN
+V
S
+ IN
–IN
OUTPUT
1
2
3
4
5
6
7
2
3
1
4
14
13
12
OUTPUT
–IN
+ IN
–V
S
+ IN
–IN
OUTPUT
OUTPUT
–IN
+ IN
+V
S
+ IN
–IN
OUTPUT
NC
1
2
3
4
5
6
7
8
NC = NO CONNECT
2
3
1
4
16-Pin SOIC
(R) Package
16
15
14
OUTPUT
–IN
+ IN
–V
S
+ IN
–IN
OUTPUT
NC
AD704
(TOP VIEW)
11
10
9
8
AD704
(TOP VIEW)
13
12
11
10
9
(E) Package 20-Terminal LCC
OUT1
OUT4
–IN1
NC
–IN4
3
2
1
20
19
PRODUCT DESCRIPTION
The AD704 is a quad, low power bipolar op amp that has the
low input bias current of a BiFET amplifier but which offers a
significantly lower I
B
drift over temperature. It utilizes Super-
beta bipolar input transistors to achieve picoampere input bias
current levels (similar to FET input amplifiers at room tempera-
ture), while its I
B
typically only increases by 5× at +125°C
(unlike a BiFET amp, for which I
B
doubles every 10°C resulting
in a 1000× increase at +125°C). Furthermore the AD704
achieves 75
µV
offset voltage and low noise characteristics of a
precision bipolar input op amp.
100
+IN1 4
NC 5
+V
S
6
NC 7
+IN2 8
AMP 1
AMP 4
18 +IN4
17 NC
16 –V
S
15 NC
14 +IN3
AD704
AMP 2
AMP 3
9
–IN2
10
OUT2
11
NC
12
OUT3
13
–IN3
NC = NO CONNECT
10
TYPICAL I
B
– nA
TYPICAL JFET AMP
1
Since it has only 1/20 the input bias current of an AD OP07, the
AD704 does not require the commonly used “balancing”
resistor. Furthermore, the current noise is 1/5 that of the
AD OP07 which makes the AD704 usable with much higher
source impedances. At 1/6 the supply current (per amplifier) of
the AD OP07, the AD704 is better suited for today’s higher
density circuit boards and battery powered applications.
The AD704 is an excellent choice for use in low frequency
active filters in 12- and 14-bit data acquisition systems, in
precision instrumentation, and as a high quality integrator. The
AD704 is internally compensated for unity gain and is available
in five performance grades. The AD704J and AD704K are rated
over the commercial temperature range of 0°C to +70°C. The
AD704A and AD704B are rated over the industrial temperature
of –40°C to +85°C. The AD704T is rated over the military
temperature range of –55°C to +125°C and is available
processed to MIL-STD-883B, Rev. C.
0.1
AD704T
0.01
–55
+25
TEMPERATURE –
°C
+125
Figure 1. Input Bias Current Over Temperature
REV. A
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
AD [ ANALOG DEVICES ]
