The author describes the concepts behind DDS architecture and contrasts it with digital PLL and the older analog technologies. He is particularly enthusiastic about sample-and-hold circuits and fractional-N PLLs, calling the latter ``the most elegant integration of PLL and DDS technologies.'' Whether or not you agree with that assessment, this book provides a clear description of the engineering tradeoffs and advantages of each approach, and introduces the reader to some of the more popular actual devices that have been manufactured. A background in electronics, signal processing or computer design is recommended. The reader is expected to already know how DSS, VCOs and PLLs fit in the overall scheme of things. Contains many oscilloscope tracings and graphs and a CD containing the text of the book in PDF format and some programs written in BASIC.