OP470ARCMDA AD [Analog Devices], OP470ARCMDA Datasheet - Page 10

• Manufacturer Part Number: OP470ARCMDA
• Description: Very Low Noise Quad Operational Amplifier
• Manufacturer: AD [Analog Devices]

OP470
Figure 6 shows peak-to-peak noise versus source resistance over
the 0.1 Hz to 10 Hz range. Once again, at low values of R
voltage noise of the OP470 is the major contributor to peak-to-peak
noise with current noise the major contributor as R
The crossover point between the OP470 and the OP400 for
peak-to-peak noise is at R
The OP471 is a higher speed version of the OP470, with a slew
rate of 8 V/ms. Noise of the OP471 is only slightly higher than
the OP470. Like the OP470, the OP471 is unity-gain stable.
Figure 6. Peak-To-Peak Noise (0.1 Hz to 10 Hz) vs. Source
Resistance (Includes Resistor Noise)
For reference, typical source resistances of some signal sources
are listed in Table I.
1000
100
10
5
R2
5
R1
100
OP400
OP471
OP470
OP11
OP470
DUT
1.24k
R3
RESISTOR
NOISE ONLY
R
200
S
– SOURCE RESISTANCE –
R4
1k
S
= 17 kW.
Figure 7. Peak-To-Peak Voltage Noise Test Circuit (0.1 Hz to 10 Hz)
OP27E
909
R5
10k
2 F
C1
1N4148
R6
600k
D1
S
increases.
100k
R8
10k
S
D2
1N4148
, the
–10–
OP15E
0.032 F
306k
Source
Strain gage
Magnetic
tapehead
Magnetic
phonograph
cartridges
Linear variable <1500 W
differential
transformer
For further information regarding noise calculations, see “Minimization of Noise
in Op Amp Applications,” Application Note AN-15.
NOISE MEASUREMENTS—
PEAK-TO-PEAK VOLTAGE NOISE
The circuit of Figure 7 is a test setup for measuring peak-to-peak
voltage noise. To measure the 200 nV peak-to-peak noise speci-
fication of the OP470 in the 0.1 Hz to 10 Hz range, the following
precautions must be observed:
1. The device must be warmed up for at least five minutes. As
2. For similar reasons, the device must be well-shielded from
3. Sudden motion in the vicinity of the device can also “feedthrough”
R9
C2
shown in the warm-up drift curve, the offset voltage typi-
cally changes 5 mV due to increasing chip temperature after
power-up. In the 10-second measurement interval, these
temperature-induced effects can exceed tens of nanovolts.
air currents. Shielding also minimizes thermocouple effects.
to increase the observed noise.
65.4k
R10
Device
Impedance
<500 W
<1500 W
<1500 W
65.4k
R11
10k
0.22 F
C3
0.22 F
R12
C4
Table I.
OP15E
Comments
Typically used in
low frequency applications.
Low I
self-magnetization problems
when direct coupling is used.
OP470 I
Similar need for low I
coupled applications. OP470
will not introduce any self-
magnetization problem.
Used in rugged servo-feedback
applications. Bandwidth of
interest is 400 Hz to 5 kHz.
5.9k
R13
B
GAIN = 50,000
V
S
very important to reduce
=
B
can be neglected.
5V
4.99k
R14
C5
1 F
B
in direct
e
REV. B
OUT