High Frequency High Precision Digital Phase Shifting Generator Based On FPGA

Digital phase shifting generator, which is an important instrument in the field of electronic technology, is widely used in the field of aerospace, communications systems, instrumentation and other research. This paper designs a high frequency high precision digital phase shifting generator, which adopts direct digital frequency synthesis (DDS) technology, field programmable gate array devices——FPGA as the hardware foundation, QuartusⅡ software platform as the development tool, and makes full use of the single chip microcomputer.DDS technology is a frequency synthesis technology, which is early proposed at the beginning of seventies. DDS technology mainly includes phase accumulator, waveform look-up table ROM, high-speed D/A conversion circuit, low pass filters and other components. Compared with other frequency synthesis technology, DDS technology’s advantage mainly includes fast frequency switching, fast frequency switching, easy to program control, low phase noise, flexible output waveform.In the development process of the system, the system adopts Altera company Cyclone Ⅱ family the FPGA chip EP2C8Q208C8as master chip waveform data and The macro crystal the technology company STC12LE5A60S2microcontroller in the design of man-machine interface. In the design, the FPGA chip and single-chip communication interface is a difficulty. In this paper, Altera Corporation’s design the tools QuartusⅡ software, combined with the VHDL language to overcome this problem.In the paper, Chapter1Introduction describes the Digital phase shifting generator’s background, the research status of the waveform signal generator at home and abroad, and the main research content.Chapter2introduces the basic principles of DDS technology in detail. Chapter3describes field programmable gate array devices-FPGA chip, hardware description languages-VHDL language, FPGA design process.Chapter4introduces man-machine interface of Digital phase shifting generator, which mainly includes hardware design and software design of man-machine interface.Chapter5describes the design based on VHDL DDS, which mainly includes the phase-locked loop circuit, FPGA and MCU communication interface module, the phase accumulator module, waveform memory ROM module, high-speed D/A conversion circuit and the design of the Low pass filter.Chapter6gives the test results of Digital phase shifting generator and the Analysis of test results. At last, the author summarize the feelings and experiences of the entire system design process, and describes the inadequacies in the system and the place which still needs to be improved.