Datasheet OP471 (Analog Devices) - 9

OP471 1000
For reference, typical source resistances of some signal sources
OP11
are listed in Table I.
OP400 TABLE I. Source OP471 Device Impedance Comments 100
Strain gauge < 500 W Typically used in
OP470 O-PEAK NOISE – nV
low-frequency applications.
RESISTOR
Magnetic < 1,500 W Low IB very important to reduce
PEAK-T NOISE ONLY
tapehead self-magnetization problems when direct coupling is used. OP471 IB can be neglected.
10 100 1k 10k 100k
Magnetic < 1,500 W Similar need for low I
RS – SOURCE RESISTANCE –
B in direct phonograph coupled applications. OP471 Figure 6. Peak-to-Peak Noise (0.1 Hz to 10 Hz) vs. Source cartridges will not introduce any Resistance (Includes Resistor Noise) self -magnetization problem. Figure 6 shows peak-to-peak noise versus source resistance over Linear variable < 1,500 W Used in rugged servo-feedback the 0.1 Hz to 10 Hz range. Once again, at low values of RS, the differential applications. Bandwidth of voltage noise of the OP471 is the major contributor to peak-to-peak transformer interest is 400 Hz to 5 kHz. noise. Current noise becomes the major contributor as RS increases. The crossover point between the OP471 and the OP400 for *For further information regarding noise calculations, see “Minimization of peak-to-peak noise is at R Noise in Op Amp Applications,” Application Note AN-15. S = 17 W. The OP470 is a lower noise version of the OP471, with a typical noise voltage density of 3.2 nV/÷Hz @ 1 kHz. The OP470 offers lower offset voltage and higher gain than the OP471, but is a slower speed device, with a slew rate of 2 V/ms compared to a slew rate of 8 V/ms for the OP471.
R3 1.24k R1 5 OP471 C1 R2 DUT 2 F 5 OP27E C4 R6 0.22 F R5 600k 909 R10 R11 65.4k 65.4k R4 D1 D2 OP15E R14 200 1N4148 1N4148 C3 4.99k e R9 0.22 F OP15E OUT 306k C5 R13 1 F 5.9k R8 10k C2 R12 0.032 F 10k GAIN = 50,000 VS = 15V
Figure 7. Peak-to-Peak Voltage Noise Test Circuit (0.1 Hz to 10 Hz) –8– REV. A