Overview

Design Resources

Evaluation Hardware

Part Numbers with "Z" indicate RoHS Compliance. Boards checked are needed to evaluate this circuit

  • EV-AD4020-REF-DGNZ ($199.00) 20-bit High Accuracy ADC Reference Design
  • EVAL-SDP-CH1Z ($199.00) Evaluation Control Board
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Features & 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

Circuit Description

System designers developing data acquisition signal chains typically require high input impedance to allow direct interface with a variety of sensors, which could have varying common-mode voltages and unipolar or bipolar single-ended or differential input signals present. The majority of the instrumentation and programmable gain instrumentation amplifiers (PGIAs) are traditionally single-ended output that cannot directly drive a fully differential, high resolution, successive approximation register (SAR) analog-to-digital converter (ADC), and require at least one signal conditioning/driver stage. However, this approach may not always facilitate stringent high accuracy performance, namely, linearity, drift, and speed at desired input levels.

This reference design incorporates the unique discrete PGIA architecture of the Analog Devices, Inc., 20-bit, 1.8 MSPS SAR ADC AD4020, a 5 V reference, and a reference buffer with on-board power supply circuitry. This solution provides a fully characterized, validated design optimized for high precision, offering unprecedented linearity (±2 ppm typical INL), low offset/gain error drift, and trackable noise and distortion (beyond −115 dB) performance at full speed for all gain options over the 0°C to 70°C temperature range. The differential output PGIA uses off-the-shelf discrete components for digitally programmable gains that have GΩ input impedance, over 92 dB common-mode rejection ratio, low output noise, and low distortion, making it suitable for directly interfacing with various sensor types and driving a high throughput, high resolution SAR ADC without compromising performance.


CONTACT ADI: For more information on the AD4020 based High Accuracy Data Acquisition Solution contact Referencedesigns@analog.com


Sample Products

Samples

Product

Description

Available Product
Models to Sample

AD4020

20-Bit, 1.8 MSPS, Precision SAR, Differential ADC

AD4020BCPZ-RL7

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