Implementation of High Resolution DDS with FPGA
Yitao Xu, Pla Uni · Journal of PLA University of Science and Technology · 2003
DDS(Direct Digital Synthesizer)plays an important role in digital communication systems.Typical application of DDS includes up/down converter,modulation/demodulation,SDR(Software Defined Radio),etc.DDS has both the advantages of high frequency resolution,rapid frequency change rate and low phase noise and the disadvantage of bad spur suppression performance with max value of -65 dB.Lookup table method is gererally used in the implementation of DDS,and quantization method for mapping phase accumulator address to table address is applied.The paper implemented DDS utilizing FPGA device and linear interpolation algorithm.This scheme utilizes all effective bits of phase accumulator address,and so can improve the performances of DDS,which has -70 dB of spur suppression value.The scheme also has the advantages of low hardware consumption,high frequency resolution,flexible design,etc.