Methods of mapping from phase to sine amplitude in direct digitalsynthesis

摘要

There are many methods for performing functional mapping fromnphase to sine amplitude (e.g., ROM look-up, coarse/fine segmentationninto multiple ROM's, Taylor series, CORDIC algorithm). The spectralnpurity of the conventional direct digital synthesizer (DDS) is alsondetermined by the resolution of the values stored in the sine table ROM.nTherefore, it is desirable to increase the resolution of the ROM.nUnfortunately, larger ROM storage means higher power consumption, lowernreliability, lower speed, and greatly increased costs. Different memoryncompression and algorithmic techniques and their effect on distortionnand trade-offs are investigated in detail. A computer program has beenncreated to simulate the effects of the memory compression andnalgorithmic techniques on the output spectrum of the DDS. For eachnmemory compression and algorithmic technique, the worst case spuriousnresponse is calculated using the computer program