1996 IEEE INTERNATIONAL FREQUENCY CONTROL SYMPOSIUM METHODS OF MAPPING FROM PHASE TO SINE AMPLITUDE IN DIRECT DIGITAL SYNTHESIS
Jouko Vankka · 1996
There are many methods for performing functional mapping from phase to sine amplitude (e.g. ROM look-up, coarse/fine segmentation into multiple ROM's, Taylor series, CORDIC algorithm). The spec- tral purity of the conventional direct digital synthe- sizer (DDS) is also determined by the resolution of the values stored in the sine table ROM. Therefore, it is desirable to increase the resolution of the ROM. Un- fortunately, larger ROM storage means higher power consumption, lower reliability, lower speed, and greatly increased costs. Different memory compres- sion and algorithmic techniques and their effect on distortion and trade-offs are investigated in detail. A computer program has been created to simulate the effects of the memory compression and algorithmic techniques on the output spectrum of the DDS.