AD9851 Datasheet

• 180 MHz Clock Rate with Selectable 6x Reference Clock Multiplier
• On-Chip High Performance 10-Bit DAC and High Speed Comparator with Hysteresis
• SFDR >43 dB @ 70 MHz A_OUT
• 32-Bit Frequency Tuning Word
• 5-Bit Phase Modulation and Offset Capability
• Simplified Control Interface: Parallel or Serial Asynchronous Loading Format
• Comparator Jitter <80 ps p-p @ 20 MHz
• 2.7 V to 5.25 V Single-Supply Operation
• Low Power: 555 mW @ 180 MHz
• Power-Down Function, 4 mW @ 2.7V
• Ultrasmall 28-Lead SSOP Packaging

• Frequency/Phase-Agile SineWave Synthesis
• Clock Recovery and Locking Circuitry for Digital Communications
• Digitally Controlled ADC Encode Generator
• Agile Local Oscillator Applications in Communications
• Quadrature Oscillator
• CW, AM, FM, FSK, MSK Mode Transmitter

The AD9851 is a highly integrated device that uses advanced DDS technology, coupled with an internal high-speed, high performance D/A converter, and comparator, to form a digitally-programmable frequency synthesizer and clock generator function. When referenced to an accurate clock source, the AD9851 generates a stable frequency and phase-programmable digitized analog output sinewave. This sinewave can be used directly as a frequency source, or internally converted to a square wave for agile-clock generator applications.

The AD9851's innovative high-speed DDS core provides a 32-bit frequency tuning word, which results in an output tuning resolution of 40 milli-Hertz, for a 180 MHz reference clock. The AD9851 contains a unique X6 reference clock multiplier circuit that obviates the need for a high-speed reference oscillator. The 6X PLL multiplier has minimal impact on SFDR and phase noise characteristics. The device provides 5-bits of digitally-controlled phase modulation which enables phase shifting of its output in increments of 180°, 90°, 45°, 22.5°, 11.25°, and any combination thereof.