PRODUCT DESCRIPTION
The AD7008 direct digital synthesis chip is a numerically controlled oscillator employing a 32-bit phase accumulator, sine and cosine look-up tables and a 10-bit D/A converter integrated on a single CMOS chip. Modulation capabilities are provided for phase modulation, frequency modulation, and both in-phase and quadrature amplitude modulation suitable for QAM and SSB generation.
Clock rates up to 20 MHz and 50 MHz are supported. Frequency accuracy can be controlled to one part in 4 billion. Modulation may be effected by loading registers either through the parallel microprocessor interface or the serial interface. A frequency-select pin permits selection between two frequencies on a per cycle basis.
The serial and parallel interfaces may be operated independently and asynchronously from the DDS clock; the transfer control signals are internally synchronized to prevent metastability problems. The synchronizer can be bypassed to reduce the transferlatency in the event that the microprocessor clock is synchronous with the DDS clock.
A power-down pin allows external control of a power-down mode (also accessible through the microprocessor interface) The AD7008 is available in 44-pin PLCC.

FEATURES
   Single +5 V Supply
   32-Bit Phase Accumulator
   On-Chip COSINE and SINE Look-Up Tables
   On-Chip 10-Bit DAC
   Frequency, Phase and Amplitude Modulation
   Parallel and Serial Loading
   Software and Hardware Power Down Options
   20 MHz and 50 MHz Speed Grades
   44-Pin PLCC

APPLICATIONS
   Frequency Synthesizers
   Frequency, Phase or Amplitude Modulators
   DDS Tuning
   Digital Modulation