A direct digital frequency synthesizer utilizing quasi-linear interpolation method

In this paper, a novel direct digital frequency synthesizer (DDFS) is introduced in which a combination of linear and even piecewise parabolic polynomial interpolation (EPIP) is used to interpolate the first quadrant of a cosine signal. An appropriate combination of these two methods is employed to maximize the spurious free dynamic range and reduce the complexity of the entire system. The even parabolic polynomial can be treated as a linear interpolation with respect to the squared of the accumulator´s output, thus the proposed system is called quasi linear interpolation (QLIP) direct digital frequency synthesizer.