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OP37GSZ-REEL7 参数 Datasheet PDF下载

OP37GSZ-REEL7图片预览
型号: OP37GSZ-REEL7
PDF下载: 下载PDF文件 查看货源
内容描述: [Low Noise, Precision, High Speed Operational Amplifier (AVCL≥5)]
分类和应用: 放大器光电二极管
文件页数/大小: 17 页 / 606 K
品牌: ADI [ ADI ]
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OP37  
APPLICATIONS INFORMATION  
Noise Measurements  
OP37 Series units may be inserted directly into 725 and OP07  
sockets with or without removal of external compensation or  
nulling components. Additionally, the OP37 may be fitted to  
unnulled 741type sockets; however, if conventional 741 nulling  
circuitry is in use, it should be modified or removed to ensure  
correct OP37 operation. OP37 offset voltage may be nulled to  
zero (or other desired setting) using a potentiometer (see figure 1).  
To measure the 80 nV peak-to-peak noise specification of the  
OP37 in the 0.1 Hz to 10 Hz range, the following precautions  
must be observed:  
The device has to be warmed-up for at least five minutes. As  
shown in the warm-up drift curve, the offset voltage typically  
changes 4 mV due to increasing chip temperature after power up.  
In the ten second measurement interval, these temperature-  
induced effects can exceed tens of nanovolts.  
The OP37 provides stable operation with load capacitances of  
up to 1000 pF and ±10 V swings; larger capacitances should be  
decoupled with a 50 W resistor inside the feedback loop. Closed  
loop gain must be at least five. For closed loop gain between five  
to ten, the designer should consider both the OP27 and the OP37.  
For gains above ten, the OP37 has a clear advantage over the  
unity stable OP27.  
For similar reasons, the device has to be well-shielded from  
air currents. Shielding minimizes thermocouple effects.  
Sudden motion in the vicinity of the device can also  
“feedthrough” to increase the observed noise.  
The test time to measure 0.1 Hz to l0 Hz noise should not  
exceed 10 seconds. As shown in the noise-tester frequency  
response curve, the 0.1 Hz corner is defined by only one zero.  
The test time of ten seconds acts as an additional zero to eliminate  
noise contributions from the frequency band below 0.1 Hz.  
Thermoelectric voltages generated by dissimilar metals at the input  
terminal contacts can degrade the drift performance. Best  
operation will be obtained when both input contacts are main-  
tained at the same temperature.  
A noise-voltage-density test is recommended when measuring  
noise on a large number of units. A 10 Hz noise-voltage-density  
measurement will correlate well with a 0.1 Hz-to-10 Hz peak-to-peak  
noise reading, since both results are determined by the white  
noise and the location of the 1/f corner frequency.  
10kR  
P
V+  
+
OP37  
OUTPUT  
Optimizing Linearity  
Best linearity will be obtained by designing for the minimum  
output current required for the application. High gain and  
excellent linearity can be achieved by operating the op amp with  
a peak output current of less than ±10 mA.  
V–  
Figure 1. Offset Nulling Circuit  
Offset Voltage Adjustment  
Instrumentation Amplifier  
The input offset voltage of the OP37 is trimmed at wafer level.  
However, if further adjustment of VOS is necessary, a 10 kW trim  
potentiometer may be used. TCVOS is not degraded (see offset  
nulling circuit). Other potentiometer values from 1 kW to 1 MW  
can be used with a slight degradation (0.1 mV/C to 0.2 mV/C) of  
TCVOS. Trimming to a value other than zero creates a drift of  
approximately (VOS/300) mV/C. For example, the change in TCVOS  
will be 0.33 mV/C if VOS is adjusted to 100 mV. The offset voltage  
adjustment range with a 10 kW potentiometer is ±4 mV. If smaller  
adjustment range is required, the nulling sensitivity can be reduced  
by using a smaller pot in conjunction with fixed resistors. For  
example, the network shown in figure 2 will have a ±280 mV ad-  
justment range.  
A three-op-amp instrumentation amplifier, shown in figure 4,  
provides high gain and wide bandwidth. The input noise of the  
circuit below is 4.9 nV/÷Hz. The gain of the input stage is set at  
25 and the gain of the second stage is 40; overall gain is 1000.  
The amplifier bandwidth of 800 kHz is extraordinarily good for  
a precision instrumentation amplifier. Set to a gain of 1000, this  
yields a gain bandwidth product of 800 MHz. The full-power  
bandwidth for a 20 V p-p output is 250 kHz. Potentiometer  
R7 provides quadrature trimming to optimize the instrumentation  
amplifier’s ac common-mode rejection.  
R5  
R8  
+
500ꢄ  
0.1%  
20kꢄ  
0.1%  
INPUT (–)  
OP37  
R1  
4.7kꢄ  
1kPOT  
4.7kꢄ  
8
1
5kꢄ  
0.1%  
R3  
V+  
390ꢄ  
R7  
V
OUT  
R4  
100kOP37  
C1  
R2  
Figure 2. Offset Voltage Adjustment  
5kꢄ  
0.1%  
100pF  
+
100ꢄ  
+18V  
R6  
R9  
500ꢄ  
0.1%  
19.8kꢄ  
OP37  
+
R10  
INPUT (+)  
500ꢄ  
NOTES:  
OP37  
TRIM R2 FOR A  
= 1000  
VCL  
TRIM R10 FOR dc CMRR  
TRIM R7 FOR MINIMUMV  
AT V  
= 20V p-p, 10kHz  
CM  
OUT  
Figure 4a. Instrumentation Amplifier  
–18V  
Figure 3. Burn-In Circuit  
REV. B  
–11–