Optimization Design Of High Precision DDS Signal Generator Based On SOPC

With the continuous development of electronic communications,people's demand for the performance and indicators of signal generators is increasing.The signal generator is widely used in electronic communication,instrument amplification,radar signal and other fields.Compared with traditional signal generators,modern electronic technology continuously improves the performance of signal generators and other aspects.Direct digital frequency synthesis technology(DDS)is a new type of frequency synthesis technology,which is characterized by high frequency accuracy,fast conversion rate and continuous phase change.Under this background,this paper designs and studies the DDS signal source.The entire system is built around the programmable logic gate array FPGA as the core hardware platform.The NIOS ? processor is embedded in it to form a programmable system-on-a-chip(SOPC).The high-precision system generates high precision through the parameter setting of the host computer QT software or TFT color screen.Signal(sine wave,square wave,triangle wave),baseband modulation signal and quadrature signal to meet the design requirements.This article gives the hardware design,software design and optimization design of the entire system,focusing on describing and analyzing the DDS generation principle,filter design and DDS optimization design based on the SOPC signal generator After the simulation,testing,debugging and improvement in the laboratory,the designed DDS signal generator can generate a variety of basic waveforms and digital baseband modulation signals(ASK,FSK,PSK,QAM)and quadrature signals.Adjustable,and the frequency resolution of the generated waveform is 0.03Hz,the phase resolution is 0.1°,and the spur is-60dBc.The design of this article mainly includes the following:The hardware design of the system.Including DDS module,baseband signal modulation module,DAC module,low-pass filter module,program-controlled amplifier module,PS2 keyboard module and TFT color screen module.System software design.Including logic writing of Verilog HDL of FPGA,C language software programming of NIOS ? 32-bit processor and writing of UI interface of QT C++host computer The logic of the hardware system is realized through Verilog language,and the serial port of the host computer controls the transformation of the waveform,frequency and phase.Optimized design of the system.It mainly optimizes the spurs of DDS,including analysis of the causes of spurs:phase truncation error,amplitude quantization error,and the impact of DAC non-ideal.For the effect of phase truncation error on spurs,waveform symmetry and jitter injection methods are applied,Polynomial interpolation method of these three kinds of suppression of spurs,through Matlab simulation to compare the effects of these several plans on suppression of spurs,and finally optimized in the system.