AD705 データシートの表示（PDF） - Analog Devices
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AD705 Datasheet PDF : 8 Pages
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5µs
100
90
10
0%
20mV
Figure 22d. Unity Gain Inverter Small Signal
Pulse Response C, = 1000 pF
10pF*
SQUARE WAVE
INPUT
5kΩ
VIN
10kΩ
+VS
0.1µF
2
7
AD705
6
3
5
4
–VS
0.1µF
VOUT
*RESPONSE IS
NEARLY IDENTICAL
FOR CAPACITANCE
VALUES OF 0 TO 100pF
4.1nF
Figure 23a. Follower Connected
in Feed-Forward Mode
5V
100
90
5µs
INPUT
10
0%
5V
OUTPUT
Figure 23b. Follower Feed-Forward
Pulse Response
VOS
ADJUST
20kΩ
+VS
1
2
8
7
AD705
6
0.1µF
5
3
4
OVERCOMPENSATION
CAPACITOR
–VS
0.1µF
Figure 24. Offset Null and Overcompensation
Connections
AD705
A High Performance Differential Amplifier Circuit
Figure 25 shows a high input impedance, differential amplifier
circuit that features a high common-mode voltage, and which
operates at low power. Table I details its performance with
changes in gain. To optimize the common-mode rejection of
this circuit at low frequencies and dc, apply a 1 volt, 1 Hz sine
wave to both inputs. Measuring the output with an oscilloscope,
adjust trimming potentiometer R6 for minimum output. For the
best CMR at higher frequencies, capacitor C2 should be replaced
with a 1.5 pF to 20 pF trimmer capacitor.
Both the IC socket and any standoffs at the op amp’s input ter-
minals should be made of Teflon* to maintain low input current
drift over temperature.
*Teflon is a registered trademark of E.I. DuPont, Co.
C1
5pF
R1
100MΩ
VIN–
SOURCE
R1'
100MΩ
VIN+
GND
R2
10MΩ
+VS
2
7
AD705
3
4
–VS
R2'
10MΩ
C2
5pF
R3
200kΩ
R5*
0.1µF
R4*
6
VOUT
0.1µF
DC CMR
ADJUST
R6
500kΩ
CIRCUIT
GAIN,
G
=
–
R2+R3
R1
(1+
R5
R4
)
VOUT = G (VIN– – VIN+)
COMMON MODE INPUT RANGE =
10 (VS – 1.5V) FOR VS = ±15V,
VCM RANGE = ±135V
RESISTORS R1 AND R1', R2 AND
R2' ARE VICTOREEN MOX-200
1/4 WATT, 1% METAL OXIDE.
*SEE TABLE I
WARNING: POTENTIAL DANGER FROM HIGH SOURCE VOLTAGE.
THIS DIFFERENTIAL AMPLIFIER DOES NOT PROVIDE GALVANIC
ISOLATION. INPUT SOURCE MUST BE REFERRED TO THE SAME
GROUND CONNECTION AS THIS AMPLIFIER.
Figure 25. A High Performance Differentials
Amplifier Circuit
Table I. Typical Performance of Differential Amplifier
Circuit Operating at Various Gains
Circuit R4
R5
Trimmed RTI Average Circuit
Gain (⍀)
(⍀)
DC CMR Drift TC
Bandwidth
(dB)
(V/؇C)
–3 dB
1
1.13 kΩ 10 kΩ ≥85
30
10
100 Ω 9.76 kΩ ≥85
30
100
10.2 Ω 10 kΩ ≥85
30
4.4 kHz
2.8 kHz
930 Hz
REV. B
–7–
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