Dual Picoampere Input
Current Bipolar Op Amp
a
AD706
FEATURE
CO NNECTIO N D IAGRAM
HIGH DC PRECISION
P lastic Mini-D IP (N) and
P lastic SO IC (R) P ackages
50 ꢁV max Offset Voltage
0.6 ꢁV/ꢂC max Offset Drift
110 pA max Input Bias Current
AMPLIFIER 1
AMPLIFIER 2
LOW NOISE
0.5 ꢁV p-p Voltage Noise, 0.1 Hz to 10 Hz
AD706
OUTPUT
–IN
1
2
3
4
8
7
6
5
Vꢀ
LOW POWER
750 ꢁA Supply Current
Available in 8-Lead Plastic Mini-DlP, Hermetic Cerdip
and Surface Mount (SOIC) Packages
Available in Tape and Reel in Accordance with
EIA-481A Standard
OUTPUT
–IN
ꢀIN
V–
ꢀIN
TOP VIEW
Quad Version: AD704
APPLICATIONS
Low Frequency Active Filters
Precision Instrumentation
Precision Integrators
P RO D UCT D ESCRIP TIO N
P RO D UCT H IGH LIGH TS
T he AD706 is a dual, 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 superbeta
bipolar input transistors to achieve picoampere input bias cur-
rent levels (similar to FET input amplifiers at room tempera-
ture), while its IB typically only increases by 5¥ at 125∞C (unlike
a BiFET amp, for which IB doubles every 10∞C for a 1000¥
increase at 125∞C). T he AD706 also achieves the microvolt
offset voltage and low noise characteristics of a precision bipolar
input amplifier.
1. T he AD706 is a dual low drift op amp that offers BiFET
level input bias currents, yet has the low IB drift of a bipolar
amplifier. It may be used in circuits using dual op amps such
as the LT 1024.
2. T he AD706 provides both low drift and high dc precision.
3. T he AD706 can be used in applications where a chopper
amplifier would normally be required but without the
chopper’s inherent noise.
100
Since it has only 1/20 the input bias current of an OP07, the
AD706 does not require the commonly used “balancing” resis-
tor. Furthermore, the current noise is 1/5 that of the OP07,
which makes this amplifier usable with much higher source
impedances. At 1/6 the supply current (per amplifier) of the
OP07, the AD706 is better suited for today’s higher density
boards.
10
TYPICAL JFET AMP
1
T he AD706 is an excellent choice for use in low frequency
active filters in 12- and 14-bit data acquisition systems, in preci-
sion instrumentation and as a high quality integrator. T he
AD706 is internally compensated for unity gain and is available
in five performance grades. T he AD706J and AD706K are rated
over the commercial temperature range of 0∞C to +70∞C.
0.1
AD706
0.01
–55
+25
+110
+125
T he AD706 is offered in two varieties of an 8-lead package:
plastic mini-DIP and surface mount (SOIC). “J” grade chips are
also available.
TEMPERATURE – ꢂC
Figure 1. Input Bias Current vs. Temperature
REV. D
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