Picoampere Input Current Quad
Bipolar Op Amp
AD704
FEATURES
CONNECTION DIAGRAMS
High dc precision
OUTPUT
–IN
1
2
3
4
5
6
7
8
16
15
14
OUTPUT
–IN
150 µV maximum offset voltage
1.5 µV/°C maximum offset voltage drift
270 pA maximum input bias current
0.3 pA/°C typical IB drift
1
4
+IN
+IN
OUTPUT
–IN
1
2
3
4
5
6
7
14
13
12
11
10
9
OUTPUT
–IN
AD704
TOP VIEW
+V
S
13 –V
S
1
4
+IN
+IN
+IN
–IN
12
11
10
9
+IN
AD704
TOP VIEW
+V
S
–V
S
2
3
–IN
Low noise: 0.5 µV p-p
+IN
–IN
+IN
OUTPUT
NC
OUTPUT
NC
Typical noise: 0.1 Hz to 10 Hz
Low power: 600 µA maximum supply current per amplifier
Dual version: AD706
2
3
–IN
(Not to Scale)
OUTPUT
8
OUTPUT
(Not to Scale)
NC = NO CONNECT
Figure 1. 14-Lead Plastic DIP (N)
Figure 2. 16-Lead SOIC (R) Package
APPLICATIONS
Industrial/process controls
Weigh scales
3
2
1
20 19
ECG/EKG instrumentation
Low frequency active filters
18
17
4
5
6
7
8
+IN4
NC
+IN1
NC
1
2
4
AD704
TOP VIEW
(Not to Scale)
16
15
14
+V
–V
S
S
GENERAL DESCRIPTION
NC
NC
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.
3
+IN2
+IN3
9
10 11 12 13
NC = NO CONNECT
Figure 3. 20-Terminal LCC
(E-20-1) Package
100
10
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.
TYPICAL JFET AMP
1
0.1
AD704
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.
0.01
–55
25
TEMPERATURE (°C)
125
Figure 4. Input Bias Current Over Temperature
Table 1. Low IB @ 125°C
Model 30V
16V
1.3 to 5V
AD8603
AD8607
AD8609
Next Generation
N/A
AD8622
Single
Dual
Quad
N/A
AD706
AD704
AD8663
AD8667
AD8669
AD8624
Rev. E
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