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ADA4940-1

PRODUCTION

Ultralow Power, Low Distortion ADC Driver

Data Sheet (Rev. E) Product Selection Table
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Overview

  • Small signal bandwidth: 260 MHz
  • Ultralow power 1.25mA
  • Extremely low harmonic distortion
    • −122 dB THD at 50 kHz
    • −96 dB THD at 1 MHz
  • Low input voltage noise: 3.9 nV/√Hz
  • 0.35 mV maximum offset voltage
  • Balanced outputs
  • Settling time to 0.1%: 34 ns
  • Rail-to-rail output: −VS + 0.1 V to +VS − 0.1 V
  • Adjustable output common-mode voltage
  • Flexible power supplies: 3 V to 7 V (LFCSP)
  • Disable pin to reduce power consumption
  • Available in LFCSP and SOIC packages

The ADA4940-1 / ADA4940-2 are low noise, low distortion differential amplifiers with very low power consumption. They are an ideal choice for driving low power, high resolution, high performance SAR and sigma-delta (Σ-Δ) analog-to-digital converters (ADCs) with resolutions up to 18 bits from dc to 1 MHz on only 1.25 mA of quiescent current. The adjustable level of the output common-mode voltage allows the ADA4940-1/ ADA4940-2 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 ADA4940-1 / ADA4940-2, differential gain configurations are easily realized with a simple external feedback network of four resistors determining the closed-loop gain of the amplifier. The ADA4940-1 / ADA4940-2 are fabricated using Analog Devices, Inc., complementary bipolar process, enabling them to achieve very low levels of distortion with an input voltage noise of only 3.9 nV/√Hz. The low dc offset and excellent dynamic performance of the ADA4940-1 / ADA4940-2 make them well suited for a variety of data acquisition and signal processing applications.

The ADA4940-1 is available in a Pb-free, 3 mm × 3 mm, 16-lead LFCSP. The ADA4940-2 is available in a Pb-free, 4 mm × 4 mm, 24-lead LFCSP. The pinout is optimized to facilitate printed circuit board (PCB) layout and minimize distortion. The ADA4940-1 / ADA4940-2 are specified to operate over the −40°C to +125°C temperature range.

Applications

  • Low power ADC drivers
  • Single-ended-to-differential converters
  • Differential buffers
  • Line drivers
  • Medical Imaging
  • Industrial Process Control
  • Portable Electronics
ADA4940-1
Ultralow Power, Low Distortion ADC Driver
ADA4940-1 Functional Block Diagram ADA4940-1 Pin Configuration ADA4940-1 Pin Confguration
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Documentation

Data Sheet 1

User Guide 2

Application Note 2

Technical Articles 5

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Software Resources

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Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

  • ADA4940

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

Open Tool

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.

Open Tool

Signal Chain Designer

Signal Chain Designer is a web-based tool designed to create and simulate complex precision signal chains. See your circuit’s performance before you commit to your PCB: transfer function, noise, power consumption, input range, and DC error. Quickly experiment with different parts and architectures. Signal chains can be exported to LTspice for further analysis.

Open Tool

SPICE Model 1

LTspice

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.

Evaluation Kits

eval board
schematic 1
schematic 2
schematic 3
EVAL-AD7768-1

AD7768-1 Evaluation Board

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Features and Benefits

  • Full featured evaluation board for the AD7768-1
  • PC control in conjunction with EVAL-SDP-CH1Z
  • PC software control and data analysis
  • Time and frequency domain
  • Standalone hardware capability

Product Details

The EV-AD7768-1FMCZ evaluation kit features the AD7768-1 24-bit, 256 kSPS analog-to-digital converter (ADC). The EVAD7768-1FMCZ board connects to the USB port of the PC via the EVAL-SDP-CH1Z motherboard. By default, power is supplied from the EVAL-SDP-CH1Z supply, which is regulated to 5 V and 3.3 V to supply the AD7768-1 and support components.

The EV-AD7768-1FMCZ software fully configures the AD7768-1 device register functionality and provides dc and ac time domain analysis in the form of waveform graphs, histograms, and associated noise analysis for ADC performance evaluation.

The EV-AD7768-1FMCZ is an evaluation board that allows the user to evaluate the features of the ADC. The user PC software executable controls the AD7768-1 over USB through the system demonstration platform (EVAL-SDP-CH1Z).

eval board
schematic 4
schematic 5
schematic 6
AMC-ADA4940-1ARZ

Amplifier Mezzanine Card for ADA4940-1

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Features and Benefits

  • Enables quick breadboarding and prototyping
  • User defined circuit configuration
  • Easy connection to other ADC evaluation boards

Product Details

The Analog Devices, Inc., amplifier mezzanine card (AMC) analog-to-digital converter (ADC) driver evaluates the performance of amplifiers in 8-lead, single and dual SOIC, 6- lead single SOT23, 8-lead dual MSOP, and 16-lead LFCSP packages. This add on board can be inserted on ADC evaluation boards using its 7-pin header. Figure 1 shows the AMC mounted on an Analog Devices, Inc., ADC evaluation board.

The AMC can support any of Analog Devices operational amplifiers and ADC drivers in different packages. The user can configure the ADC driver as a Sallen-Key low-pass, high-pass, or band-pass filter, as a multiple feedback low-pass, high-pass, or band-pass filter, or as an inverting and noninverting operational amplifier. The user can also configure the AMC to drive a singleended, fully differential, or a single-ended signal to a differential ADC.

Optimized power and ground planes ensure low noise and high speed operation. Component placement and power supply bypassing are optimized for maximum circuit flexibility and performance. The AMC evaluation board accepts 0402 or 0603 surface mount technology (SMT) components, 1206 bypass capacitors, and 2.54 mm headers.

All components are placed on the primary side. No components are placed on the secondary side.

EVAL-FDA-1

Universal Evaluation Board for Single Differential Amplifiers

Buy Now View Details

Product Details

The Universal Differential Amplifier Evaluation Boards can be used to evaluate single, high speed, fully differential amplifiers. The evaluation boards are bare boards that enable users to quickly prototype a variety of differential or single-ended circuits, which minimizes risk and reduces time to market. These boards are all RoHs Compliant. See references below on what board to order by lead count and package.

EVAL-AD7768-1
AD7768-1 Evaluation Board
EV-AD7768-1FMCZ - Angle View EV-AD7768-1FMCZ - Bottom View EV-AD7768-1FMCZ - Top View
AMC-ADA4940-1ARZ
Amplifier Mezzanine Card for ADA4940-1
AMC-ADA4XXX-1ARZANGLE-web AMC-ADA4XXX-1ARZBOTTOM-web AMC-ADA4XXX-1ARZTOP-web
EVAL-FDA-1
Universal Evaluation Board for Single Differential Amplifiers

Reference Designs

CN0513 Board
CN0513 Board
CN0513 Block Diagram
AD4020 Reference Design Block Diagram
CN0513 Circuits from the lab

20-Bit, 1.8 MSPS, ±2.5 ppm INL, Low Drift, High Accuracy Data Acquisition Solution

View Detailed Reference Design

Features and Benefits

  • Data acquisition solution fully characterized over 0°C to 70°C
  • Guaranteed 20-bit no missing codes
  • INL: ±2 ppm, DNL: ±0.25 ppm
  • Throughput: 1.8 MSPS
  • Offset error drift: ±3.5 ppm/°C; gain error drift: ±6 ppm/°C
  • SNR: 98 dB at G = 1, 92 dB at G = 10, fIN = 1 kHz
  • THD: −120 dB at G = 1, −116 dB at G = 10, fIN = 1 kHz
  • Oversampled dynamic range: 102 dB at 900 kSPS, OSR = 2
  • Software programmable bipolar input ranges (±1 V to ±10 V)
    • Allows single-ended and differential signals
  • CMRR: 92 dB typical
  • GΩ input impedance allows direct interface with sensors
  • Ease of use features reduce system power and complexity
  • ADC Input overvoltage clamp protection sinks up to 50 mA
  • On-board 5 V reference and buffer
  • First conversion accurate, no latency/pipeline delay
  • Fast conversion time allows low SPI clock rates
  • SPI-/QSPI-/MICROWIRE-/DSP-compatible serial interface
CN0513
20-Bit, 1.8 MSPS, ±2.5 ppm INL, Low Drift, High Accuracy Data Acquisition Solution
CN0513 Board
CN0513 Block Diagram
AD4020 Reference Design Block Diagram

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