Linearity analysis of direct digital chirp synthesizer in the presence of amplitude quantization

A simple algorithm is developed for calculating the linearity of the chirp signal generated by a direct digital chirp synthesizer in the presence of amplitude quantization. The linearity and signal to quantization noise ratio (SQNR) for the conventional uniform mid-tread and mid-rise quantizers along with a proposed nonuniform quantizer are evaluated using the algorithm. Numerical results demonstrate that the proposed nonuniform quantizer can improve the linearity by almost one order of magnitude with ignorable SQNR degradation, which makes it an optimal candidate for a direct digital chirp synthesizer compared with the conventional uniform mid-tread and mid-rise quantizers.