LT1037ACH Linear Technology, LT1037ACH Datasheet - Page 10

• Manufacturer Part Number: LT1037ACH
• Description: Low Noise/ High Speed Precision Operational Amplifiers
• Manufacturer: Linear Technology

APPLICATIONS
LT1007/LT1037
As with all operational amplifiers when R
be created with R
creating additional phase shift and reducing the phase
margin. A small capacitor (20pF to 50pF) in parallel with R
will eliminate this problem.
Noise Testing
The 0.1Hz to 10Hz peak-to-peak noise of the LT1007/
LT1037 is measured in the test circuit shown (Figure 5a).
The frequency response of this noise tester (Figure 5b)
indicates that the 0.1Hz corner is defined by only one zero.
The test time to measure 0.1Hz to 10Hz noise should not
exceed ten seconds, as this time limit acts as an additional
zero to eliminate noise contributions from the frequency
band below 0.1Hz.
Measuring the typical 60nV peak-to-peak noise perfor-
mance of the LT1007/LT1037 requires special test
precautions:
1. The device should be warmed up for at least five
2. For similar reasons, the device must be well shielded
10
*DEVICE UNDER TEST
NOTE: ALL CAPACITOR VALUES ARE FOR
NONPOLARIZED CAPACITORS ONLY
minutes. As the op amp warms up, its offset voltage
changes typically 3 V due to its chip temperature
increasing 10 C to 20 C from the moment the power
supplies are turned on. In the ten-second measurement
interval these temperature-induced effects can easily
exceed tens of nanovolts.
from air currents to eliminate the possibility of thermo-
10
VOLTAGE GAIN
= 50,000
–
+
LT1007
LT1037
0.1 F
100k
*
F
Figure 5a. 0.1Hz to 10Hz Noise Test Circuit
and the amplifier’s input capacitance,
U
INFORMATION
U
2k
4.7 F
W
24.3k
F
+
–
LT1001
> 2k, a pole will
100k
0.1 F
U
4.3k
F
3. Sudden motion in the vicinity of the device can also
A noise voltage density test is recommended when mea-
suring noise on a large number of units. A 10Hz noise
voltage density measurement will correlate well with a
0.1Hz to 10Hz peak-to-peak noise reading since both
results are determined by the white noise and the location
of the 1/f corner frequency.
Current noise is measured in the circuit shown in Figure 6
and calculated by the following formula:
22 F
2.2 F
electric effects in excess of a few nanovolts, which
would invalidate the measurements.
“feedthrough” to increase the observed noise.
i
n
110k
e
no
100
SCOPE
R
1007/37 F05a
2
IN
1
= 1M
1
M
130
500k
500k
nV
101
100
Figure 6
90
80
70
60
50
40
30
0.01
–
+
Figure 5b. 0.1Hz to 10Hz Peak-to-
Peak Noise Tester Frequency
Response
101
100k
LT1007
LT1037
2
0.1
1 2
FREQUENCY (Hz)
1007/37 F06
1
e
no
10
1007/37F05b
100