Description

The AD9851 is a highly integrated device that uses advancedDDS technology, coupled with an internal high-speed, highperformance D/A converter, and comparator, to form a digitally-programmablefrequency synthesizer and clock generatorfunction. When referenced to an accurate clock source, theAD9851 generates a stable frequency and phase-programmabledigitized analog output sinewave. This sinewave can be useddirectly as a frequency source, or internally converted to a squarewave for agile-clock generator applications.The AD9851'sinnovative high-speed DDS core provides a 32-bit frequencytuning word, which results in an output tuning resolution of 40milli-Hertz, for a 180 MHz reference clock. The AD9851contains a unique X6 reference clock multiplier circuit thatobviates the need for a high-speed reference oscillator. The 6XPLL multiplier has minimal impact on SFDR and phase noisecharacteristics. The device provides 5-bits of digitally-controlledphase modulation which enables phase shifting of its output inincrements of 180°, 90°, 45°, 22.5°, 11.25°, and any combinationthereof.