3 nV /√Hz, Low Power Instrumentation Amplifier
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Product Details

The AD8421 is a low cost, low power, extremely low noise, ultra-low bias current, high speed instrumentation amplifier which is ideally suited for a broad spectrum of signal conditioning and data acquisition applications. This breakthrough product features the highest CMRR available, allowing it to extract low-level signals in the presence of high-frequency common mode noise over a wide temperature range.

The 10 MHz bandwidth, 35 V/µs slew rate, and 0.7 µs settling time to 0.01% (G = 1) allow the AD8421 to amplify high-speed signals and excel in applications that require high channel-count multiplexed systems. Even at high gain, the current feedback architecture preserves this performance, for example, at G = 100, the bandwidth is 2 MHz and the settling time is 0.6 µs. The AD8421 has excellent distortion performance, allowing use in demanding applications such as vibration analysis.

The AD8421 delivers industry-leading 3 nV/√Hz input voltage noise and 200 fA/√Hz current noise with only 2 mA quiescent current, making it an ideal choice for measuring low-level signals. For applications with significant source impedance, the AD8421 employs novel process technology and innovative design techniques to provide groundbreaking noise performance limited only by the sensor.

The AD8421 uses a unique input protection method to give it robust inputs while still maintaining very low noise. This input protection allows voltages 40 V from the opposite supply rail without damage.

A single resistor sets gains between 1 and 10,000. The reference pin can be used to apply a precise offset to the output voltage.

The AD8421 performance is specified from −40°C to +85°C and has typical performance curves to 125°C. It is available in MSOP and SOIC packages.


  • Medical instrumentation
  • Precision data acquisition
  • Microphone preamplification
  • Vibration analysis
  • Multiplexed input applications
  • ADC driver

Product Lifecycle

checked Recommended for New Designs

This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

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ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.

AD8421 Material Declaration
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The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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Evaluation Boards Pricing displayed is based on 1-piece.
Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.