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  5. ADA4945-1


Features and Benefits

  • Broad power supply range: 3 V to 10 V
  • Wide input common-mode voltage range: −VS to +VS − 1.3 V
  • Rail-to-rail output
  • Fully specified dual power mode operation
    • 4 mA full power mode (145 MHz)
    • 1.4 mA low power mode (80 MHz)
  • Full power mode
    • Low harmonic distortion
    • −133 dBc HD2 and −140 dBc HD3 at 1 kHz
    • −133 dBc HD2 and −116 dBc HD3 at 100 kHz
    • Fast settling time
      • 18-bit: 100 ns
      • 16-bit: 50 ns
    • Input voltage noise: 1.8 nV/√Hz, f = 100 kHz
  • ±115 μV maximum offset voltage from −40°C to +125°C
  • Adjustable output clamps for ADC input protection

Product Details

The ADA4945-1 is a low noise, low distortion, fully differential amplifier with two selectable power modes. The device operates over a broad power supply range of 3 V to 10 V. The low dc offset, dc offset drift, and excellent dynamic performance of the ADA4945-1 makes it well suited for a variety of data acquisition and signal processing applications. The device is an ideal choice for driving high resolution, high performance successive approximation register (SAR) and Σ-Δ analog-to-digital converters (ADCs) on 4 mA of quiescent current (full power mode). The device can also be selected to operate on 1.4 mA of quiescent current (low power mode) to scale the power consumption to the desired performance necessary for an ADC drive application. The adjustable common-mode voltage allows the ADA4945-1 to match the input common-mode voltage of multiple ADCs. The internal common-mode feedback loop provides exceptional output balance, as well as suppression of even order harmonic distortion products.

With the ADA4945-1, differential gain configurations are achieved with a simple external feedback network of four resistors determining the closed-loop gain of the amplifier. The ADA4945-1 is fabricated using Analog Devices, Inc., proprietary, silicon germanium (SiGe), complementary bipolar process, enabling the device to achieve low levels of distortion with an input voltage noise of only 1.8 nV/√Hz (full power mode).

The ADA4945-1 is available in a RoHS-complaint, 3 mm × 3 mm, 16-lead LFCSP. The ADA4945-1 is specified to operate from −40°C to +125°C.


  • Low power Σ-Δ, PulSAR®, and SAR ADC drivers
  • Single-ended to differential converters
  • Differential buffers
  • Medical imaging
  • Process control
  • Portable electronics

Product Lifecycle icon-recommended 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.

Evaluation Kits (4)

Documentation & Resources

  • View All (14)
  • Data Sheets (1)
  • Application Notes (2)
  • User Guides (3)
  • Webcasts (2)
  • Videos (4)
  • Technical Articles (2)
  • Tools & Simulations


    LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.


    Models for the following parts are available in LTspice:


    Precision ADC Driver Tool

    The Precision ADC Driver Tool is a web application that simulates the performance of precision ADC and driver combinations. Potential issues with driver selection, kickback settling, and distortion are flagged, and design tradeoffs can be quickly evaluated. Simulations and calculations include system noise, distortion, and settling of the ADC input

    Precision ADC Driver Tool

    SPICE Models

    Design Tools

    ADI DiffAmpCalc™

    ADI's new ADI DiffAmpCalc™ is a free, downloadable calculator for designing differential amplifier circuits. The tool is easy to use and features an interactive user interface to quickly get you up and running.

    Reference Designs (4)

    Design Resources

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    Part Number Material Declaration Reliability Data Pin/Package Drawing CAD Symbols, Footprints & 3D Models
    ADA4945-1ACPZ-R2 Material Declaration Reliability Data 16-Lead LFCSP (3mm x 3mm w/ EP)
    ADA4945-1ACPZ-R7 Material Declaration Reliability Data 16-Lead LFCSP (3mm x 3mm w/ EP)
    ADA4945-1ACPZ-RL Material Declaration Reliability Data 16-Lead LFCSP (3mm x 3mm w/ EP)
    Wafer Fabrication Data

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