a FEATURES DC PERFORMANCE 25 V max Offset Voltage (AD705T) 0.6 V/؇C max Drift (AD705K/T) 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 0.5 V p typ Noise, 0.1 Hz to 10 Hz 600 A max Supply Current AC PERFORMANCE 0.15 V/µs Slew Rate 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 APPLICATIONS Low Frequency Active Filters Precision Instrumentation Precision Integrators
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 industrystandard 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 picoAmp
Picoampere Input Current Bipolar Op Amp AD705 CONNECTION DIAGRAM Plastic Mini-DIP (N) Cerdip (Q) and Plastic SOIC (R) Packages OFFSET NULL
levels, 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. The AD705 is internally compensated for unity gain and is available in five performance grades. The AD705J and AD705K are rated over the commercial temperature range of 0°C to +70°C. The AD705A and AD705B are rated over the industrial temperature range of –40°C to +85°C. The AD705T is rated over the military temperature range of –55°C to +125°C and is available processed to MIL-STD-883B, Rev. C. The AD705 is offered in three varieties of 8-pin package: plastic DIP, hermetic cerdip and surface mount (SOIC). “J” grade chips are also available. PRODUCT HIGHLIGHTS
1. The AD705 is a low drift op amp that offers BiFET level input bias currents, yet has the low IB drift of a bipolar amplifier. It upgrades the performance of circuits using op amps such as the LT1012. 2. The combination of Analog Devices’ advanced superbeta processing technology and factory trimming provides both low drift and high dc precision. 3. The AD705 can be used in applications where a chopper amplifier would normally be required but without the chopper’s inherent noise and other problems.
REV. B Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
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