Features and Benefits

  • 400 MSPS Internal DDS Clock Speed
  • 48-bit frequency tuning word
  • 14-bit Programmable Phase Offset
  • Integrated 14-bit DAC
    • Excellent Dynamic Performance
    • Phase noise ≤ 135 dBc/Hz @ 1 KHz offset
    • −80 dB SFDR @ 160 MHz (±100 KHz offset IOUT)
  • 25 Mb/s write-speed serial I/O control
  • 655 MHz programmable input dividers for the phase
    • frequency detector (÷M, ÷N) {M, N = 1..16} (bypassable)
  • Programmable RF divider (÷R) {R = 1, 2, 4, 8} (bypassable)
  • 8 phase/frequency profiles
  • 1.8 V supply for device operation
  • 3.3 V supply for I/O and charge pump
  • Software controlled power-down
  • 48-lead LFCSP package
  • Automatic linear frequency sweeping capability (in DDS)
  • Programmable charge pump current (up to 4 mA)
  • Phase modulation capability
  • Multichip synchronization
  • Dual-mode PLL lock detect
  • 655 MHz CML-mode PECL-compliant driver

Product Details

The AD9956 is Analog Devices’s first AgileRF synthesizer. The device is comprised of a DDS and PLL circuitry. The DDS features a 14-bit DAC operating up to 400 MSPS and a 48-bit frequency tuning word. The PLL Circuitry includes a phase detector with scaleable 200 MHz inputs (pre-scalar inputs operate up to 650 MHz) and digital control over the charge pump current. The device also includes a 650 MHz PECL driver with programmable slew rates.The AD9956 uses advanced DDS technology, an internal high-speed, high performance D/A converter and an advance phase-detector/charge pump combination to enable the synthesis of digitally-programmable, frequency-agile analog output sinusoidal waveforms up to 2.7 GHz. The AD9956 is designed to provide fast frequency hopping and fine tuning resolution (48-bit frequency tuning word). Information is loaded into the AD9956 via a serial I/O port which has a device write speed of 25 MBit/sec. The AD9956 DDS block also supports a user defined linear sweep mode of operation.

The AD9956 is specified to operate over the extended automotive range of −40°C to +125°C.


  • Agile LO frequency synthesis
  • FM chirp source for radar and scanning systems
  • Automotive radars
  • Test and measurement equipment
  • Acousto-optic device drivers

Product Lifecycle icon-recommended Recommended for New Designs

This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

Documentation & Resources

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  • Data Sheets (1)
  • Application Notes (20)
  • Product Highlight (1)
  • Frequently Asked Questions (1)
  • Technical Articles (21)
  • Webcasts (2)
  • Application Notes
    Frequently Asked Questions
    Technical Articles

    Tools & Simulations

    IBIS Models

    AD9956 IBIS Models

    Design Tools

    ADIsimDDS (Direct Digital Synthesis)

    ADIsimDDS uses mathematical equations to model and illustrate the overall performance of the selected device. ADIsimDDS calculates the required FTW, given the reference clock frequency and desired output frequency. This tool also models an estimate of the overall spectral performance, and allows the user to explore the effects of external reconstruction filters.

    Design Resources

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    Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.