Direct Digital Frequency Synthesizers using high-order Polynomial Approximation

Direct digital frequency synthesizers (DDFS) using high-order polynomial approximation were discussed. The read only memory (ROM)-less DDFS used a sine/cosine generator block that interpolates the sine function using an optimized polynomial expression with constant coefficients. Higher spurious-free dynamic range (SFDR) is obtained compared to Taylor expansion. Polynomial coefficients are chosen using non-linear Nelder-Mead simplex optimization to maximize DDFS output SFDR