The Research And Simulation Of Multi-wave Signal Source Based On FPGA

With the signal generator being widely used in all kinds of filed, more and more requirements have been brought up. Direct Digital Frequency Synthesis(DDS) technology is born at this historic moment. DDS has gained much attention worldwide and is widely used in digital communication systems because of its advantages. Field-programmable gate array(FPGA) device takes the advantage of fast speed, highly integrated, strong reliability and field programmable. The DDS system designed based on FPGA is stable in system, and can meet most of the demands.DDS has many advantages compared with traditional signal generator, while the biggest drawback is that the output waveforms are spurious, which leads to signal error. Research into the root cause of spurious signals’ generation and methods to reduce them thus becomes the research direction of this paper.This paper introduced the DDS signal source in Chapter 1. By introducing the principle of DDS, DDS was successfully simulated of several waveforms. By changing the frequency control word, DDS simulated different frequencies of the same waveform. This paper introduced the method to minimize stray in Chapter 2. Causes for spurious signals, especially the spurious signals brought by phase truncation were analyzed. Frequency domain spectrums resulted by phase truncation with different factor were simulated. By joining random sequence and changing the structure of phase accumulation to minimize stray, the paper simulated the two methods and demonstrated the methods worked to reduce stray. According to the stray of phase truncation, simulation was come true.