Elimination of non-harmonic spurious in direct digital synthesis

Direct digital synthesis (DDS) is rapidly gaining in popularity as an alternative to traditional synthesis techniques as the operating speeds of digital devices increase. However, apart from their many advantages such as unprecedented tuning speeds, fine channel spacing resolution, unconditional stability properties, waveshape generation etc., the DDS is inherently plagued by spurious frequency components. Techniques have previously been developed to redistribute the energy of the spurious components surrounding the fundamental output to spurious components far from the carrier by suitably modulating the synthesised waveform. However, the paper shows that the fundamental mechanism of generation of the spurious components may be removed, thus allowing the use of low resolution digital to analogue converters (DACs) to produce good spurious performance, a previously unattainable goal