A ROM-less direct digital frequency synthesiser using a polynomial approximation
C. Meenakarn, Apinunt Thanachayanont · 2004
This paper describes the design and implementation of a sine-output ROM-less direct digital frequency synthesiser by using a polynomial approximation of which a maximum error less than 2e-4 can be achieved for phase values between 0 to /spl pi//2. The full-period sinewave is generated by using a quadrant-decode technique. This yields a very high spectral purity sinewave output. System-level approximation and experimental results using an FPGA show that the maximum harmonic distortion is less than -67.4 dBc and -64.8 dBc respectively.