OP27CJGB Datasheet, PDF (15/22 Pages) Texas Instruments – LOW-NOISE HIGH-SPEED PRECISION OPERATIONAL AMPLIFIERS

OP27A, OP27C
LOW-NOISE HIGH-SPEED PRECISION OPERATIONAL-AMPLIFIER
SLOS100E − FEBRUARY 1989 − REVISED FEBRUARY 2010
APPLICATION INFORMATION
noise testing (continued)
1. The device should be warmed up for at least five minutes. As the operational amplifier warms up, the
offset voltage typically changes 4 μV due to the chip temperature increasing from 10°C to 20°C starting
from the moment the power supplies are turned on. In the 10-s measurement interval, these
temperature-induced effects can easily exceed tens of nanovolts.
2. For similar reasons, the device should be well shielded from air currents to eliminate the possibility of
thermoelectric effects in excess of a few nanovolts, which would invalidate the measurements.
3. Sudden motion in the vicinity of the device should be avoided, as it produces a feedthrough effect that
increases observed noise.
100
90
80
70
60
50
40
30
0.01
0.1
1
10
100
f − Frequency − Hz
0.1 μF
10 Ω
OP27
Device
Under
Test
100 kΩ
−
2 kΩ
+
Voltage
Gain = 50,000
4.7 μF
LT1001
+
−
100 kΩ
24.3 kΩ _{0.1 μF}
4.3 kΩ
2.2 μF
22 μF
Oscilloscope
R_in = 1 MΩ
110 kΩ
NOTE: All capacitor values are for nonpolarized capacitors only.
Figure 26. 0.1-Hz to 10-Hz Peak-to-Peak Noise Test Circuit and Frequency Response
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