今天整理板子的时候发现个AD9912的板子，想起来了以前做的DDS，好久没有做数字电路了，看来还得好好看看其他的，全面发展。

ADI公司的AD9912是集成了14位DAC的直接数据频率合成器(DDS),具有48位频率调整字(FTW),能以每步间隔不大于4 uHz合成频率.AD9912还集成了系统时钟PLL,其基准时钟可低至25MHz,广泛用在低抖动精密时钟发生器,无线基站,保密通信以及快速频率跳频.

主要特性:
1 GSPS internal clock speed (up to 400 MHz out directly)
Integrated 1 GSPS 14-bit DAC
48-bit frequency tuning word
Differential HSTL Comparator
Flexible System Clock Input accepts either crystal or external reference clock.
On-chip Low-Noise PLL REFCLK Multiplier
2 SpurKiller channels
Low Jitter clock doubler for frequencies up to 750 MHz
Single-ended CMOS Comparator; frequencies < 50MHz
Programmable output divider for CMOS output
Serial I/O control
Excellent Dynamic Performance
Software controlled power-down
64-lead LFCSP package
Phase Noise @ 95MHz using Vectron VCC6 87.5MHz Oscillator:
100 Hz Offset: -103 dBc/Hz
10 kHz Offset: -133 dBc/Hz
1 MHz Offset: -136 dBc/Hz

应用:
Agile LO frequency synthesis
Low jitter, fine tune clock generation
Test and measurement equipment
Wireless Base Stations, Controllers
Secure Communications
Fast frequency hopping