ANALOG DEVICES Dual Very Low Noise Precision Operational Amplifier 0-270 FEATURES _ Savannah at KHz Max, offering comparable performance ® Very Low $nv/A/HZ @ kHz Max 10 P Mi's industry standard OP-27 . The OP-270 features an input offset voltage below 75,V and « Very High Gen J500V/mY Min an offset drift under guaranteed over the full mil* Outstanding CM’HH : 1084B Min unitary temperatures range. Open-loop gain of the OP-270 is e View Rate .
0 Pp-270 ground noise and power supply fluctuations. Power consumption of the dual OP-270 is one-third less than two OP-27s, & significant advantage for power conscious applications. The OP-270 is unity-gain stable with a gain bandwidth product of MHz and a slew rate of The OP-270 offers excellent amplifier matching which is important for applications such as multiple gain blocks, low noise instrumentation amplifiers, dual buffers, and low-noise active filters.
0-270 TYPICAL PERFORMANCE CHARACTERISTICS VOLTAGE NOISE DENSITY vs FREQUENCY o b new CORNER ~ otz FREQUENCY (Hz) CURRENT NOISE DENSITY vs FREQUENCY Tam 25 Py 1 CORNER = 200Kz CURRENT NOISE [nR//HE FREQUENCY (2) INPUT BIAS CURRENT vs TEMPERATURE ’ r crier INPUT BIAS CURRENT { 2 w75 TEMPERATURE s VOLTAGE NOISE DENSITY vs SUPPLY VOLTAGE T G REGEXP SUPPLY VOLTAGE (VOLTS) INPUT OFFSET VOLTAGE WARM-UP OFFSET vs TEMPERATURE VOLTAGE DRIFT T mete TEMPERATURE (C) e sycamores) UNFIT OFFSET CURRENT (nd) INPUT OFFSET CU
6-270 TYPICAL PERFORMANCE CHARACTERISTICS CMR vs FREQUENCY 1m0 A W m FREQUENCY iz} wor 1% PSR vs FREQUENCY T 2800 Stowe FREQUENCY i o com OPEN-LOOP GAIN, PHASE SHIFT vs FREQUENCY T 2C Yo a Toy APSE man =62 Gain KT SIM FREQUENCY (tiz PHASE SHIFT (DEG] DPEN.
0-270 CHANNEL SEPARATION TEST CIRCUIT = s000 BURN-IN CIRCUIT >—1—0 31 + i taus ook T i L eed 5 1ov APPLICATIONS INFORMATION VOLTAGE AND CURRENT NOISE The OP-270is Avery low-noises dual op amp, exhibiting atypical voltage noise of only Tz @ kHz. The exceptionally low noise characteristics of the OP-270 is in pant achieved by operating the input transistors at sigh collector currents since the voltage noise is inversely proportional 1o the square root of the -5 collector current.
0-270 Figure 2 also shows the relationship between total seine and source resistance, but at 10Hz. Total noise increases more quickly than shown in Figure 1 because current noise is inversely proportional to the square root of frequency. In Figure 2, current noise of the OP-270 dominates the total noise when Rg> Ski. From Figures and 2 it can be seen that to reduce total noise, source resistance must be kept toa minimum.
0-270 FIGURE 4: Peak-To-Peak Voltage Noise Test Circuit (0.1Hz To 10Hz) 3 12042 At 0 o090 a2 our chisel Toxic w0 AN B5.ak &S sank © 00320 GAIN = 50,000 Voo 118y FIGURE §: 0.1+z To 10H7 Peak-To-Peak Voltage Noise Test Circuit Frequency Response Gam FREQUENCY (Ha) as an additional pole to eliminate noise contribution from the frequency band below 0.1Hz. 5.
0-270 FIGURE T: Current Noise Density Test Circuit Fo 1280 SPECTRUM ANALYZER BARGAIN 1300 Pty NOISE MEASUREMENT ~ CURRENT NOISE DENSITY The test circuit shown in Figure 7 can be used to measure current noise density. The formula relating the voltage output 1 current noise density is: where: G = gain of Rg = 100k{) source resistance CAPACITIES LOAD DRIVING AND POWER SUPPLY CONSIDERATIONS The OP-270 Is unity-gain stable and is capable of driving large capacities roads without oscillating.
0-270 UNITY-GAIN BUFFER APPLICATIONS When Ry < 10002 and the Input is driven with a fast, large signal pulse the output waveform wit look as shown in Figure 9. During the fast feed through-like portion of the output, the input protection diodes effectively short the output to the input, and a current, limited only by the output short-circuit protection, will be drawn by the signal generator.
0-270 FIGURE 12: 5-Band Low Noise Graphic Equalizer "2 sank omit gourd MM o8 ome TV I par.F TANTALUM TANTALUM 10t 800th otz FIVE-BAND LOW NOISE STEREO GRAPHIC EQUALIZER The graphic equalizer circuit shown in Figure 12 provides 1548 of boost or cut over a §-band range. Sign ail-io-noise ratio over a 20k Hz bandwidth is better than 100dB referred to & 3V rms input. Larger conductors can be replaced by active conductors but this reduces the signal-to-noise ratio.
0-270 FIGURE 15: Dual Programmable Gain Amplifier BAE BAYS 50T PING G (MIB} — 9 L88) omen 5 T b Veges WRITE | @ Control o