Title :
Spectral purity of direct digital frequency synthesizers
Author :
Kroupa, Venceslav F.
Author_Institution :
Czechoslovak Acad. of Sci., Praha, Czechoslovakia
Abstract :
A short introduction to the problems of frequency synthesis is given. Mathematical models suitable for direct digital frequency synthesizers (DDFS) which provide quasi-periodic omission of clock pulses such as continued fraction expansion, modified Engel series expansion, and modulo-N arithmetic are investigated. It is shown that in these instances the peaks of the phase-time modulation function do not exceed one clock period. Using the Fourier series algorithm all spurious signals in the output wave can be found. However, the procedure might be lengthy. Pulse train, square wave, and sine wave outputs are discussed
Keywords :
digital circuits; frequency synthesizers; DDFS; Fourier series algorithm; continued fraction expansion; direct digital frequency synthesizers; frequency synthesis; modified Engel series expansion; modulo-N arithmetic; phase-time modulation function; pulse train outputs; quasi-periodic omission of clock pulses; sine wave outputs; spectral purity; spurious signals; square wave outputs; Arithmetic; Clocks; Costs; Electromagnetic scattering; Frequency synthesizers; Hardware; Mathematical model;
Conference_Titel :
Frequency Control, 1990., Proceedings of the 44th Annual Symposium on
Conference_Location :
Baltimore, MD
DOI :
10.1109/FREQ.1990.177538
