DDS中ROM存储的线性分层插值压缩方法

Hierachical Linear Interpolation Approach of ROM Compression in Direct Digital Frequency Synthesizer

在直接数字频率合成器(Direct Digital Frequency Synthesizer,DDS)中,传统ROM存储表的正弦函数幅度压缩法为了达到高压缩率,通常采用较为复杂的正弦近似函数,增加了硬件电路的复杂度。本文提出一种线性分层插值的ROM表压缩方法,通过分层、分段线性插值近似,可以显著减少相位点幅度的量化比特数,同时各层可以共用同一个插值和重建电路,使得硬件的复杂度显著降低。理论分析和仿真结果表明,本文提出的ROM表压缩方法在不显著增加硬件电路复杂度的情况下,可以有效提高ROM表的压缩比。

Complex approximate functions are often used in traditional sine amplitude compression approach for ROM compression in direct digital frequency synthesizer to achieve high compression rate. This paper proposes a new hierachical linear interpolation approach for ROM compression and phase-to-sine amplitude conversion of sinusoid output DDS. Experimental results show that the proposed approach can achieve a higher compression rate with equal spectral performances and simpler hardware structure than most of the previous works.