AD705 General Description
The AD705 is a low power bipolar op amp that has the low input bias current of a BiFET amplifier but which offers a significantly lower IB drift over temperature. The AD705 offers many of the advantages of BiFET and bipolar op amps without their inherent disadvantages. It utilizes superbeta bipolar input transistors to achieve the picoampere input bias current levels of FET input amplifiers (at room temperature), while its IB typically only increases 5 times vs. BiFET amplifiers which exhibit a 1000X increase over temperature. This means that, at room temperature, while a typical BiFET may have less IB than the AD705, the BiFET's input current will increase to a level of several nA at +125°C. Superbeta bipolar technology also permits the AD705 to achieve the microvolt offset voltage and low noise characteristics of a precision bipolar input amplifier.
The AD705 is a high quality replacement for the industry- standard OP07 amplifier while drawing only one sixth of its power supply current. Since it has only 1/20th the input bias current of an OP07, the AD705 can be used with much higher source impedances, while providing the same level of dc precision. In addition, since the input bias currents are at picoAmplevels, the commonly used "balancing" resistor (connected between the noninverting input of a bipolar op amp and ground) is not required. The AD705 is an excellent choice for use in low frequency active filters in 12- and 14-bit data acquisition systems, in precision instrumentation and as a high quality integrator.
AD705 Maximum Ratings
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±18 V
Internal Power Dissipation2. . . . . . . . . . . . . . . . . . . 650 mW
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±VS
Differential Input Voltage3. . . . . . . . . . . . . . . . . . . . . ±0.7 V
Output Short Circuit Duration . . . . . . . . . . . . . . . . Indefinite
Storage Temperature Range (N, R) . . . . . . . 65°C to +125°C
Storage Temperature Range (Q) . . . . . . . . . 65°C to +150°C
Operating Temperature Range
AD705J/K . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C
AD705A/B . . . . . . . . . . . . . . . . . . . . . . . . . 40°C to +85°C
AD705T . . . . . . . . . . . . . . . . . . . . . . . . . . 55°C to +125°C
Lead Temperature Range (Soldering 60 sec) . . . . . . . . +300°C
AD705 Features
DC PERFORMANCE
100 pA max Input Bias Current (AD705K)
600 pA max IB Over MIL Temperature Range (AD705T)
114 dB min CMRR (AD705K/T)
114 dB min PSRR (AD705T)
200 V/mV min Open Loop Gain
800 kHz Unity Gain Crossover Frequency
10,000 pF Capacitive Load Drive Capability
Low Cost
Available in 8-Pin Plastic Mini-DlP, Hermetic Cerdip and Surface Mount (SOIC) Packages
MIL-STD-883B Processing Available
Dual Version Available: AD706
Quad Version: AD704
AD705 Typical Application
Low Frequency Active Filters
Precision Instrumentation
Precision Integrators
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