Research On Complex Function Generator Based On FPGA

Function generator is a significant signal resource with multi-waveform, applied widely in the development and test field. It's highly worthy to design an accurate, steady and flexible function generator.At present, there're many kinds of function generator with full functions, but expensive and not satisfied with some special requirements, such as the pseudo random signal. A complex function generator based on FPGA is designed for the projects of organism electrical killing and food safety detection in this thesis. First the feasibility of the design is studied. Then the method of realizing arbitrary waveform with the direct digital synthesis is discussed. Next the periphery circuit of the system is designed. Afterwards the characteristic of the 2~n pseudo random signal is analyzed. Finally the output of arbitrary waveform was realized by image processing and simulated by MATLAB and Quartus.This thesis is divided into six chapters. The first chapter described the development trend of the technology of frequency synthesis, introduced the application status of the programmable logic device, indicated the significance of designing a function generator based on FPGA, and pointed out the study background and the main contents. The second chapter described the structure and the theory of direct digital frequency synthesizer, analyzed the main characteristic of the DDS system, discussed the different methods of frequency synthesis, and determined the method of the system design. The third chapter introduced the periphery circuit of the system, including the configuration circuit of FPGA, the digital to analog convertor module, the selective filter circuit and the power amplifier circuit. The fourth chapter introduced the logic control of FPGA, designed the clock control module, the pipelining phase accumulator, and finished the output of many kinds of signals, such as sine, triangle, saw tooth, rectangle, 2~n pseudo random signal and any arbitrary hand-drawn waveforms. The fifth chapter analyzed the simulation of signals, discussed the simulation results and the system error. The last summarized the final conclusions of innovation and shortage.For the projects of organism electrical killing and food safety detection, the complex function generator based on FPGA is designed with the method of direct digital frequency synthesis, which can produce not only the general signals but also the 2~n pseudo random signal and any arbitrary hand-drawn waveforms. The method has the advantages of low cost, low power, short development cycle and flexible for design, which can generate highly practical value and widely potential applications.