Piece-wise parabolic interpolation for direct digital frequency synthesis

Abstract

In this paper, a compact architecture and implementation for direct digital frequency synthesis (DDFS) is presented. It uses a smaller lookup table for sinusoidal functions compared to existing architectures. The computation of the sinusoidal values is performed by a parabolic interpolation structure, thus only interpolation coefficients need to be stored in the read-only memory (ROM). The ROM size is consistently less than 1 Kbit for SFDR values up to 85 dBc.