This paper studies the system and hardware design of the Arbitrary Waveform Generator based Direct Digital Synthesizer in detail. And a theoretical analysis of the system performance is also given.The basic conception and theory have been dealt with at the beginning. Then, it analyses the output spectrum of DDS from frequency, and some experiment results are given. On the basis of these, it introduces three reasons, which caused great output spur. From these reasons, the methods for improving spur are introduced, and a novel method is introduced. Then we analyse the feasibility of this new method. After studying these theories, we design a set of scheme for this system and finish the hardware circuit of DDS. Tested by instrument, this system is up to requirement.
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