Analog Devices Inc. AD4021/AD4022 Differential SAR ADCs

Analog Devices AD4021/AD4022 Differential SAR ADCs are high accuracy, high speed, low power, 20-bit, Easy Drive, precision successive approximation register (SAR) analog-to-digital converters (ADCs) that operate from a single VDD power supply. The device's reference voltage is applied externally and can be set independent of the supply voltage. Also, the AD4021/AD4022 power scales linearly with throughput.

The AD4021/AD4022 ADCs feature Easy Drive, which reduces both signal chain complexity and power consumption while enabling higher channel density. The reduced input current, particularly in high-Z mode, coupled with a long signal acquisition phase, eliminates the need for a dedicated ADC driver. The Easy Drive feature enables the range of companion circuitry to broaden that is capable of driving the AD4021/AD4022.

The AD4021/AD4022 ADCs offer input span compression that eliminates the need to provide a negative supply to the ADC driver amplifier while preserving access to the full ADC code range. The input overvoltage clamp eliminates the need for external protection diodes by protecting the ADC inputs against overvoltage events and minimizing disturbances on the reference pin. The fast device throughput up to 1MSPS (AD4021) or 500kSPS (AD4022) allows users to accurately capture high-frequency signals and to implement oversampling techniques to alleviate the challenges associated with antialias filter designs. The decreased serial peripheral interface (SPI) clock rate requirements, reduce digital input/output power consumption, broadens digital host options, and simplifies the task of sending data across digital isolation. The SPI-compatible serial user interface is compatible with 1.8V, 2.5V, 3V, and 5V logic by using the separate VIO logic supply.

The AD4021/AD4022 Differential SAR ADCs are available in 10-lead packages of 3mm × 3mm LFCSP and 3mm × 4.90mm MSOP. They are pin-compatible with the AD4003/AD4007/AD4011 16/18-Bit SAR ADCs.


  • Easy Drive
    • Greatly reduced input kickback
      • Input current reduced to 0.5μA/MSPS
    • Enhanced acquisition phase, ≥77% of cycle time at 1MSPS
    • First conversion accurate, no latency or pipeline delay
    • Input span compression for single-supply operation
    • Fast conversion allows low SPI clock rates
    • Input overvoltage clamp protection sinks up to 50mA
    • SPI-/QSPI-/MICROWIRE-/DSP-compatible serial interface
  • High performance
    • Differential analog input range: ±VREF, VREF from 2.4V to 5.1V
    • 1MSPS (AD4021) or 500kSPS (AD4022) options
    • INL: ±3.1ppm maximum
    • Guaranteed 20-bit no missing codes
    • SNR: 100.5dB at fIN = 1kHz at VREF 5V
    • THD: −123dB at fIN = 1kHz, −100dB at fIN = 100kHz
    • SINAD: 89dB at fIN = 900kHz
  • Oversampled dynamic range
    • 104dB for OSR = 2
    • 131dB for OSR = 1024
  • Low power
  • Single 1.8V supply operation with 1.71V to 5.5V logic interface
    • 2.7mW at 500kSPS (VDD only)
    • 83μW at 10kSPS
  • 10-lead packages: 3mm × 3mm LFCSP, 3mm × 4.90mm MSOP
  • Guaranteed operation: -40°C to +125°C


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


Block Diagram - Analog Devices Inc. AD4021/AD4022 Differential SAR ADCs
Published: 2020-01-24 | Updated: 2022-03-11