The Research Of Multi-waveform Generator Based On DDS/FPGA

The Direct Digital Synthesis (DDS) technique adops full-digital tynthesis methods. The generated signals have advantages of high adopts full-digital synthesis frequency resolutions, frequency switching, continuous phase while frequency switching, low noise phase being able to generate arbitrary waveforms. This paper studies the system of the Multi-Waveform Generator based DDS and FPGA. DDS is the key technique to it. DDS can control amplitude, phase and frequency of waveform in precision, so it can synthesize arbitrary waveform. The drawback of the DDS is high level of spurious frequencies. There are three main sources of spurious signal in DDS: the truncation of the phase accumulator bits addressing the sine ROM, the finite precision of the sine samples stored in the ROM and nonlinear of the digital-to-analog conversion. Reduction of spurious signals is key to modify output spectrum of DDS.After studied many ways of declining the spurious signal, this paper advances neutralized disturbance technique, which greatly improves the quality of the output signal spectrum.EP1S80B956C6 is a high performance Digital Signal Processors, which is fit for system of Multi-Waveform Generator. Methods of spurs-reduced, on the platform of Quartus II, with the design methods of Verilog HDL language and schematic, can be easily applied on FPGA to modify spectrum of output signal.Considering merits of DDS and FPGA, This paper designs a system of Multi-Waveform Generator based on DDS/FPGA, which can synthesize kinds of waveform: sin,cos,triangle,sawtooth,square,AM,SSB,FM,2ASK,2FSK,π/4 -QDPSK. In this way, one waveform generator can supply signals for many working conditions which greatly facilitates our work.