Analog Devices Inc. ADAR7251 16-Bit ADCs

Analog Devices ADAR7251 features 4-channel, 16-Bit, simultaneous sampling analog-to-digital converters (ADCs) specially designed for applications such as data acquisition systems, automotive LSR-FMCW, and FSK-FMCW radar systems. The devices’ CONV_START input and DATA_READY output signals synchronize the ADCs with an external ramp to support the targeted applications. An on-chip phase-locked loop (PLL) enables a range of clock frequencies for maximum system flexibility. Each of ADAR7251's four channels includes a programmable gain amplifier (PGA), low noise amplifier (LNA), an equalizer, decimation filter, and multi-bit Σ-Δ ADC. The PGA and LNA have a 45dB gain range in 6dB steps. At the maximum gain setting, the ADAR7251 ADCs offer a low 2.4nV/√Hz input-referred voltage noise. ADAR7251's front-end circuitry allows a direct connection to an MMIC output with very few external passive components. The design of the ADAR7251 ADCs eliminates the need for driver operational amplifiers, a high-order anti-aliasing filter, and external bipolar supplies. As a result, these ADCs enable easy connections to digital signal processors (DSPs) and microcontroller units (MCUs) in the system Designers can use the ADAR7251 ADCs for precise channel-to-channel drift matching. Operating over a wide signal bandwidth, ADAR7251’s serial and parallel interfaces support programmable sample rates ranging from 300kSPS to 1.8MSPS.


  • Low noise: 2.4nV/√Hz input-referred voltage noise at a maximum gain setting
  • Wide input signal bandwidth: 500kHz at 1.2MSPS sample rate, 16-bit resolution
  • Additional sample rates supported: 300kSPS, 450kSPS, 600kSPS, 900kSPS, and 1.8MSPS
  • 4 differential simultaneous sampling channels
  • No active anti-aliasing filter required
  • LNA and PGA with 45dB gain range in 6dB steps
  • Selectable equalizer
  • Flexible data port supports serial or parallel mode
  • Supports FSK mode for FMCW radar systems
  • On-chip 1.5V reference
  • Internal oscillator/PLL input: 16MHz to 54MHz
  • High-speed serial data interface
  • SPI control
  • 2 general-purpose inputs/outputs
  • 48-lead LFCSP_SS package
  • Temperature range: −40°C to +125°C
  • Single supply operation of 3.3V
  • Qualified for automotive applications


  • Automotive LSR systems
  • FSK-FMCW radar systems
  • Data acquisition systems

Functional Block Diagram

Analog Devices Inc. ADAR7251 16-Bit ADCs


Published: 2016-12-05 | Updated: 2022-03-11