Abstract ：Signal generator of synthesizing frequency is an important source in the field of scientific research, teaching experiment and electronic measurement. With the development of science and technology, the stability, precision and resolution of source are required more and more highly in every field of high precision measurement.
Direct digital synthesis (DDS) is a technique for using digital data processing blocks as a means to generate a frequency- and phase-tunable output signal referenced to a fixed-frequency precision clock source. With the development of VLSI and microelectronic technology, today’s high-performance, functionally-integrated, and small package-sized DDS products are fast becoming an alternative to traditional frequency-agile analog synthesizer solutions.
This paper briefly introduces several currently used frequency synthetic methods, lays emphasis on DDS’ working principle, performance and application, and analysis of its phase noise and spurious signal. DDS’ phase truncation error and amplitude quantizing spurious are mainly discussed in this paper. Then, the paper describes in detail a engineering realization method to work on a direct digital frequency source with high accuracy by adopting a AD9851 chip.
By experiments, it has been proved that DDS signal generator has good reliability, ease of implementation and high output frequency resolutions, it can meet the people’s continual elevated requires
KEY WORDS: Signal generator, DDS, AD9851, Microcontroller
