Title :
An exact spectral analysis of a number controlled oscillator based synthesizer
Author :
Garvey, Joseph F. ; Babitch, Daniel
Author_Institution :
California Microwave Inc., Sunnyvale, CA, USA
Abstract :
An exact analysis of a number controlled oscillator (NCO)-based synthesizer is presented. A description of an NCO-based synthesizer is provided. A continuous Fourier transform is developed for an arbitrary stepped waveform like a direct digital synthesizer (DDS) output. A method for generating the mapping PROM used by a DDS is described, so that the output waveform distortion is minimized. Computer-based calculations are presented to provide insight to the workings of a DDS. Among other results it is shown that the output cleanliness is not a function of the number of phase bits in the NCO. Rather, the phase bits in the NCO simply represent the resolution with which frequencies may be selected
Keywords :
Fourier transforms; frequency synthesizers; spectral analysis; NCO-based synthesizer; continuous Fourier transform; mapping PROM; number controlled oscillator; spectral analysis; Clocks; Communication system control; Communications technology; Computer architecture; Fourier transforms; Frequency synthesizers; Microwave oscillators; PROM; Spectral analysis; Watches;
Conference_Titel :
Frequency Control, 1990., Proceedings of the 44th Annual Symposium on
Conference_Location :
Baltimore, MD
DOI :
10.1109/FREQ.1990.177539
