The Design Of High Rate Arbitrary Signal Generator Based On DDS

With the rapid development of science and technology,many fields have proposed new requirements for the characteristics of the signal being measured.The development of high-performance signal generators has become a fierce competition among countries.At present,the high-performance signal generator is usually much expensive.Its structure is too complicated.It ' s difficult to maintain in the later stage.Designers use different methods to improve and optimize these problems.This paper introduce a high-speed arbitrary signal generator based on direct digital synthesis(DDS)which is designed by field programmable gate array(FPGA)technology and MATLAB software.The design relies on the actual needs of enterprises conducts a lot of research and experiment on the structure,measurement method and result analysis of the signal generator.The results show that the signal generator has high slew rate,high transfer rate,low delay,and the ability to generate arbitrary signals.The main work is as follows:(1)According to the technical status and the cost of the signal generator,an implementation scheme combining FPGA technology and MATLAB software is proposed.Here are the technical specifications of this signal generator:The design adopts that a system clock is 100MHz and a high-speed DAC achieves a conversion rate of 50MSPS.The signal generator has a frequency resolution of 23.28 mHz and a cut-off frequency of seventh-order Butterworth filter is 40MHz.The resistance of the potentiometer is 5K?.It is used.There are two 145MHz bandwidth operational amplifiers.It can output conventional waveforms such as sine wave,square wave,triangle wave and sawtooth wave.The highest frequency is 390KHz.The waveform distortion rate is less than 1.5%.It can output analog modulated wave and digital modulated wave with controllable parameters.(2)According to literature,the USB3.0+FPGA+DAC of architecture is used by hardware design.The USB3.0 interface is used to transfer data generated by MATLAB to the FPGA hardware system with a maximum transfer rate of 5Gb/s.The data transfer rate between USB3.0 and FPGA is 3200Mb/s.The FPGA chip is used to implement hardware driver and data processing functions,including USB3.0 communication,DDS module,high-speed DAC module and data reading and writing control module.(3)The type of signal generated is designed by MATLAB software.It configures serial communication with the FPGA.Its own communication toolbox function and it can implement multiple types of signals.(4)The waveform of the target signal is observed by an oscilloscope.The signal parameters is measured.The waveform distortion is analyzed under different sampling points.The waveform quality of the generated signal is judged.The minimum sampling point is determined.The high-speed signal generator is designed in this paper.It has the advantages of small size,light weight,easy maintenance.It can be used to test and repair electronic instruments,and provide specific signals as teaching instruments,which has high use value.