AD705JN DIP-8 Picoampere Input Current Bipolar Op Amp

The AD705JN is a single, precision, picoampere input current bipolar operational amplifier manufactured by Analog Devices, one of the world's leading designers of high-performance analog integrated circuits. It is specifically engineered to bridge the gap between traditional bipolar op-amps and FET-input designs, offering the low DC offset and excellent long-term stability of a bipolar amplifier combined with the ultra-low input bias current typically found only in FET-input op-amps.

This unique combination makes the AD705JN exceptionally well-suited for amplifying signals from very high impedance sources — such as photodiodes, pH electrodes, ion-selective probes, piezoelectric sensors, and electrometer-grade measurement circuits — where even small bias currents from a standard op-amp would introduce significant errors.

With an input bias current of just 60 pA typical (250 pA max), the AD705JN draws negligible current from the signal source, preserving the integrity of even the most delicate sensor outputs. Its input offset voltage of 90 µV typical and excellent long-term stability ensure accurate DC-coupled amplification, while the 110 dB common-mode rejection ratio (CMRR) provides outstanding immunity to noise and interference.

Despite its precision performance, the AD705JN is remarkably power-efficient, consuming only 380 µA of supply current, making it an excellent choice for battery-powered, portable, and remote-sensing applications. The wide supply range of ±2 V to ±18 V (or single-supply equivalent) provides flexibility for integration into a wide variety of system designs.

The IC is internally compensated for unity-gain stability and operates reliably over the commercial temperature range of 0 °C to +70 °C. The standard DIP-8 through-hole package is breadboard-friendly and ideal for prototyping, educational projects, lab instrumentation, and small-batch production runs.

Whether you're building a transimpedance amplifier for a photodiode, a biomedical signal front-end, a precision instrumentation system, or a high-impedance buffer, the AD705JN delivers the accuracy, low noise, and minimal input loading that demanding analog applications require.

Specifications

General

• Manufacturer: Analog Devices Inc.
• Part Number: AD705JN
• Product Category: Precision Operational Amplifier
• Amplifier Type: Bipolar Input, Single Op-Amp
• Number of Channels: 1
• Package / Case: PDIP-8 (through-hole)
• Mounting Style: Through Hole

Electrical Characteristics

• Input Bias Current (I_B): 60 pA typical, 250 pA max
• Input Offset Voltage (V_OS): 90 µV typical, 250 µV max
• Input Offset Voltage Drift: 1.2 µV/°C typical
• Open-Loop Gain (A_OL): 1000 V/mV (120 dB) typical
• Common-Mode Rejection Ratio (CMRR): 110 dB typical
• Power Supply Rejection Ratio (PSRR): 110 dB typical
• Supply Current: 380 µA (per channel)
• Supply Voltage Range: ±2 V to ±18 V (dual) or single supply equivalent
• Slew Rate: 0.15 V/µs typical
• Gain Bandwidth Product: 800 kHz typical
• Input Noise Voltage: 330 nV/√Hz at 1 kHz
• Input Impedance: Very high (typical of low-bias bipolar input stage)

Environmental

• Operating Temperature Range: 0 °C to +70 °C (commercial grade)
• Storage Temperature Range: −65 °C to +150 °C

Applications

• Photodiode Transimpedance Amplifiers (light sensors, optical receivers)
• Electrometer Circuits for extremely low-current measurement
• pH Meters and Ion-Selective Electrode Interfaces
• Biomedical Instrumentation — ECG, EEG, and EMG front-ends
• High-Impedance Sensor Amplifiers (piezoelectric, capacitive)
• Precision Voltage and Current References
• Low-Level Signal Conditioning in data acquisition systems
• Integrators and Sample-and-Hold Circuits
• Battery-Powered Precision Instruments
• Strain Gauge and Load Cell Interfaces
• Smoke Detectors and Photometric Equipment
• Industrial Process Control and Automation
• Laboratory Test Equipment and scientific instruments
• Educational Electronics and University Lab Experiments