Quad Picoampere Input Current
Bipolar Op Amp
a
AD704
FEATURES
CONNECTION DIAGRAMS
High DC Precision
14-Lead Plastic DIP (N)
14-Lead CerDIP (Q) Packages
16-Lead SOIC
(R) Package
75 V Max Offset Voltage
1 V/؇C Max Offset Voltage Drift
150 pA Max Input Bias Current
0.2 pA/؇C Typical IB Drift
Low Noise
1
2
3
4
5
6
7
14
1
2
3
4
5
6
7
8
OUTPUT
16
15
OUTPUT OUTPUT
OUTPUT
13
12
4
1
–IN
+IN
–IN
+IN
–V
4
–IN
1
–IN
0.5 V p-p Typical Noise, 0.1 Hz to 10 Hz
Low Power
+IN
14
13
12
11
10
9
+IN
AD704
(TOPVIEW
AD704
(TOPVIEW)
11
10
9
+V
S
–V
+V
S
S
S
600 A Max Supply Current per Amplifier
MIL-STD-883B Processing Available
Available in Tape and Reel in Accordance
with EIA-481A Standard
Dual Version: AD706
)
+IN
–IN
+IN
+IN
–IN
+IN
2
2
3
3
–IN
–IN
8
OUTPUT
OUTPUT
OUTPUT
OUTPUT
NC
NC
APPLICATIONS
NC = NO CONNECT
Industrial/Process Controls
Weigh Scales
ECG/EKG Instrumentation
Low Frequency Active Filters
20-Terminal LCC
(E) Package
3
2
1
20 19
PRODUCT DESCRIPTION
+IN4
NC
18
17
16
+IN1 4
NC 5
+V
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 IB drift over temperature. It utilizes super-beta
bipolar input transistors to achieve picoampere input bias current
levels (similar to FET input amplifiers at room temperature),
while its IB typically only increases by 5× at 125°C (unlike a
BiFET amp, for which IB 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.
AMP 1
AMP 4
–V
6
S
AD704
S
AMP 2
AMP 3
NC 7
15
14
NC
+IN3
+IN2 8
9
10 11 12 13
NC = NO CONNECT
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.
100
10
TYPICAL JFET AMP
1
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
is 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
+125
TEMPERATURE –
C
Figure 1. Input Bias Current Over Temperature
REV. C
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may result from its use. No license is granted by implication or otherwise
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© Analog Devices, Inc., 2002