Kroupa V F
Institute of Radio Engineering and Electronics, Academy of Sciences of the Czech Republic, Praha, Czech Republic.
IEEE Trans Ultrason Ferroelectr Freq Control. 1999;46(3):481-6. doi: 10.1109/58.764832.
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.
讨论了直接数字频率合成器（DDFS）在数模（DAC）输出端出现的虚假相位和幅度干扰问题。当商用合成器缺少输出滤波器（例如，整套所谓的数控振荡器）或由于某些原因提供较低时钟频率时，就会出现这种情况。近期关于DDFS的书籍作者提到了这一现象，但没有给出解释。本文将详细探讨这个问题。
