PRODUCT OVERVIEW
The AD9956 is Analog Devices’ newest AgileRF synthesizer. The device is comprised of DDS and PLL circuitry. The DDS features a 14-bit DAC operating at up to 400 MSPS and a 48-bit frequency tuning word (FTW). The PLL circuitry includes a phase frequency detector with scaleable 200 MHz inputs (divider inputs operate up to 655 MHz) and digital control over the charge pump current. The device also includes a 655 MHz CML-mode PECL-compliant driver with programmable slew rates. The AD9956 uses advanced DDS technology, an internal high speed, high performance DAC, and an advanced phase frequency detector/charge pump combination, which, when used with an external VCO, enables the synthesis of digitally programmable, frequency-agile analog output sinusoidal waveforms up to 2.7 GHz.

FEATURES
   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
   200 MHz phase frequency detector inputs
   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

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