ABSTRACT The problem of the spurious phase and amplitude disturbances in direct digital frequency synthesizers (DDFS) at the digital-to-analog (DAC) output is discussed. Such a situation is met when a commercial synthesizer lacks the output filter (e.g., the whole set of the so-called Number-controlled oscillators) or is supplied, for some reasons, with a lower clock frequency. Authors of recent books on DDFS mention this phenomenon but lack to provide the explanation. The problem is dealt with in detail in this paper.
1999 IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control Vol. 46, pp. 481-486, 1999
© 1999, by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.