Analog Devices Inc. AD4020 20-Bit Precision SAR ADC

Analog Devices Inc. AD4020 20-Bit Precision SAR ADC is a low-power, low-noise, 1.8MSPS 20-Bit Precision Successive Approximation Register (SAR) Analog-to-Digital Converter. The AD4020 ADC offers ease-of-use features that lower the signal chain power, reduce signal chain complexity, and enable higher channel density. Operating using a 1.8V supply, the AD4020 ADC provides a ±VREF fully differential input range with a 2.4V to 5.1V. VREF range. In turbo mode, the AD4020 ADC consumes only 15mW at 1.8MSPS with a minimum SCK rate of 71MHz. The ADC achieves ±3.1ppm integral nonlinearity (INL). The AD4020 guarantees no missing codes at 20 bits with 100.5dB typical signal-to-noise ratio (SNR). 

The Analog Devices AD4020 ADC's SPI-compatible versatile serial interface provides seven different modes. Using the SDI input, designers can daisy-chain several ADCs on a single 3-wire bus. The AD4020 ADC is specified for operation from -40°C to +125°C and is compatible with 1.8V, 2.5V, 3V, and 5V logic.


  • Guaranteed 20-bit no missing codes
  • Low Power
    • 9.0mW at 1.8MSPS (VDD only)
    • 83μW at 10kSPS, 15mW at 1.8MSPS (total)
  • Ease-of-Use Features Reduce System Power and Complexity
    • Input overvoltage clamp circuit
    • Reduced nonlinear input charge kickback
    • High-Z mode
    • Long acquisition phase
    • Input span compression
    • Fast conversion time allows low SPI clock rates
    • SPI-programmable modes, read/write capability, status word
  • 1.8MSPS maximum throughput
  • ±3.1ppm maximum INL
  • SNR: 100.5dB typical at 1kHz, 99dB typical at 100kHz
  • THD: −123dB typical at 1kHz, −100dB typical at 100kHz
  • Differential Analog Input Range
    • 0V to VREF with VREF from 2.4V to 5.1V
  • Single 1.8V supply operation with 1.71V to 5.5V logic interface
  • SAR architecture: no latency/pipeline delay
  • Valid first accurate conversion
  • −40°C to +125°C operating temperature range
  • SPI/QSPI/MICROWIRE/DSP compatible serial interface
  • Ability to daisy-chain multiple ADCs and busy indicator
  • 10-lead packages: 3mm x 3mm LFCSP, 3mm x 4.90mm MSOP


  • Automatic test equipment
  • Machine automation
  • Medical equipment
  • Battery-powered equipment
  • Precision data acquisition systems

Block Diagram

Block Diagram - Analog Devices Inc. AD4020 20-Bit Precision SAR ADC


Additional Resources

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Published: 2017-10-31 | Updated: 2022-04-28