Research On DDS Based On CORDIC Algorithm And Implementation With FPGA

With the development of digital circuits and microelectronic technology,signal generator is being widely used in radar,communication,navigation,electronic countermeasure and instrument and apparatus.During actual practices,users have increasingly strict requirements on resolution,spectrum purity and the frequency range of the signal generator.The high precision signal generator based on Direct Digital Synthesis(DDS)has been a solution to many technological problems in previous signal generators designed with frequency synthesis,therefore it is honored as the heart of the electronic system.DDS signal generator was designed in the thesis by using Electronic Design Automation(EDA)technology.The thesis began with the overview of the current development status and working principle of DDS technology,the principle and structure of CORDIC algorithm,and the principle of lock-in amplifier and digital integrating circuit.Then the thesis laid stress on elaboration of the design of DDS.Based on the above-mentioned relevant theories,the thesis substituted the traditional ROM lookup table(LUT)structure with CORDIC algorithm,detected the signal amplitude with lock-in amplifier,converted the sine-cosine wave caused by the CORDIC module into square wave and triangle wave,and improved the lock-in amplifier in order to save hardware resources.FPGA development board DE2-115 produced by Altera was used for the hardware platform of the system design.At first,the model was established in Matlab/Simulink for simulation verification.Then Verilog HDL language was used in Quartus ? for the design and simulation of DDS and symbol files were finally generated in Quartus ? environment to substantialize the design module on FPGA.At last,the systematic function of DDS was simulated and verified with the use of Modelsim,and comparison was made of the hardware costs of DDS system designed with the two methods respectively before and after the improvement.The test results show that:Firstly,based on the CORDIC algorithm,the functional simulation and output wave of various modules of DDS signal generator have verified the validity of module function.Secondly,the adoption of CORDIC algorithm has saved hardware resources,and the improved design will save more hardware resources.Finally,the thesis will serve as experimental basis for further studies and development in the future.