Picoampere Input Current Quad
Bipolar Op Amp
AD704
Rev.
E
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FEATURES
High dc precision
150 V maximum offset voltage
1.5 V/°C maximum offset voltage drift
270 pA maximum input bias current
0.3 pA/°C typical IB drift
Low noise: 0.5 V p-p
Typical noise: 0.1 Hz to 10 Hz
Low power: 600 A maximum supply current per amplifier
APPLICATIONS
Industrial/process controls
Weigh scales
ECG/EKG instrumentation
Low frequency active filters
GENERAL DESCRIPTION
The AD704 is a quad, low power bipolar op amp that has the
low input bias current of a BiFET amplifier and offers a signifi-
cantly lower IB drift over temperature. It uses superbeta bipolar
input transistors to achieve picoampere input bias current levels
(similar to FET input amplifiers at room temperature), while its
IB typically increases only by 5× at 125°C (unlike a BiFET amp,
for which IB doubles every 10°C, resulting in a 1000× increase at
125°C). In addition, the AD704 achieves 150 μV offset voltage and
the low noise characteristics of a precision bipolar input op amp.
Because it has only 1/20 the input bias current of an OP07, the
AD704 does not require the commonly used balancing resistor.
Furthermore, the current noise is 1/5 that of the OP07, which
makes the AD704 usable with much higher source impedances.
At 1/6 the supply current (per amplifier) of the 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 stability. The AD704J is
rated over the commercial temperature range of 0°C to 70°C.
The AD704A is rated over the industrial temperature of 40°C
to +85°C. The AD704S is rated over the military temperature
range of 55°C to +125°C, processed to MIL-STD-883B.
CONNECTION DIAGRAMS
OUTPUT
1
–IN
2
+IN
3
+VS 4
OUTPUT
14
–IN
13
+IN
12
–VS
11
+IN
5
–IN
6
OUTPUT
7
+IN
10
–IN
9
OUTPUT
8
1
4
2
3
AD704
TOP VIEW
(Not to Scale)
00818-
001
OUTPUT
1
–IN
2
+IN
3
+VS 4
OUTPUT
16
–IN
15
+IN
14
–VS
13
+IN
5
–IN
6
OUTPUT
7
8
+IN
12
–IN
11
OUTPUT
NC
10
9
1
4
2
3
AD704
TOP VIEW
(Not to Scale)
NC = NO CONNECT
00818-
002
Figure 1. 14-Lead Plastic DIP (N)
Figure 2. 16-Lead SOIC (R) Package
4
+IN1
5
NC
6
+VS
7
NC
8
+IN2
NC = NO CONNECT
18
+IN4
17
NC
16
–VS
15
NC
14
+IN3
13
–I
N3
12
OU
T3
11
NC
10
OU
T2
9
19
20
1
2
3
–I
N2
–I
N4
OU
T4
NC
OU
T1
–I
N1
1
4
2
3
AD704
TOP VIEW
(Not to Scale)
00818-
003
Figure 3. 20-Terminal LCC
(E-20-1) Package
100
10
1
0.1
0.01
–55
25
125
TEMPERATURE (°C)
TY
P
IC
A
L
I
B
(
n
A)
TYPICAL JFET AMP
AD704
00818-
004
Figure 4. Input Bias Current Over Temperature
Table 1. Low IB @ 125°C
Model
30V
16V
1.3 to 5V
Next Generation
Single
N/A
N/A
Dual
Quad