Textbook in PDF format

This tutorial provides an excellent treatment of the theoretical and practical aspects of direct digital synthesis (DDS) and is written for the practicing engineer. A number of applications are described including frequency/phase hopping, clock generation, and digital modulation.
Fundamentals of DDS Technology
Understanding the Sampled Output of a DDS Output
Frequency/phase-hopping Capability of DDS
The DDS Output Spectrum
High-speed Reference Clock Considerations
Interfacing to the DDS Output
DDS as a Clock Generator
Replacing/Integrating a PLL with a DDS Solution
Digital Modulator Application of DDS
Using Aliased Images to Generate Nyquist Frequencies from a DDS
Ancillary DDS Techniques, Features, and Functions
Techniques for Bench Evaluation of a DDS Solution
Integrating DDS-based Hardware into a System Environment
DDS Product Selection Guide
Appendices: Glossary, Acronyms, Pseudo Random Generator, Jitter Reduction