摘要
提出了一种适用于数字视频编码器的直接数字频率合成器 DDFS(Direct Digital Frequency Synthesizer)新结构 .通过采用相位截断噪声整形技术 ,使所需要的 ROM面积下降为传统结构的 1/ 8.同时采用了其它优化策略进一步减少了 ROM的面积 ,整个 DDFS仅需要 115 2 bit的 ROM.DDFS输出在 PAL 制式下信噪比为 6 9d B,NTSC制式下为 70 .7d
A DDFS (Direct Digital Frequency Synthesizer) suitable for the digital vedio encoder is presented.By adopting the technique of noise shaping,the size of ROM is reduced to 1/8 of conventional one.The circuit size is further reduced by using other optimization methods.The worst S/N under PAL mode is 69dB,while 70 7dB under NTSC mode.
