Design Of Arbitrary Waveform Generator Based On FPGA And PXI Bus

The signal source has occupied a very important position in modern testing filed,and going to the direction of miniaturization,high-speed development in current electronic information era.Arbitrary waveform generator(AWG)which is the common testing and measuring equipment is the typical signal source,arbitrary waveform generator after several generations of development,a simple digital circuit is gradually improved from the original complex analog oscillation circuit.Nowadays arbitrary waveform generator not only can generate simple sine wave,rectangular wave and other standard waveform,more is applied to simulate the output of some unconventional waveform signal and the user needs to customize arbitrary waveform.Arbitrary waveform generator can generate a variety of waveform signals,which is widely used in the field of testing and measuring,military research,space exploration,medical equipment and other fields,and having made great contributions to the development of science and technology.The structure form of AWG is mainly desktop instrument and bus card virtual instrument in current market.The paper is based on a certain project,aim to design 3U single channel arbitrary waveform generator module board based on PXI bus,because of the miniaturization of the PXI bus interface,therefore,it is a kind of bus card virtual instrument.The paper builds a architecture of PC + PXI Bus +FPGA + SDRAM + DAC,based on the analysis of direct digital frequency synthesis(DDS)technology,and putting forward the design scheme of DDS technology by using FPGA,realizing sine wave and other standard waveform,as well as the output of custom arbitrary waveform,and putting forward a new method to adjust the offset of the amplitude in the traditional arbitrary waveform generator,and also putting forward the method of using the same size of memory to realize the different way of waveform storage,this method can improve the performance of wave.This paper first describes the development of AWG and DDS technology and the importance of PXI bus technology in the field of AWG,and introducing the research status of AWG products at home and abroad;Then according to the actual design requirements and the feasibility analysis of key technology,DDS implementation plan and the overall design scheme of AWG are determined,selecting the appropriate chips to design hardware circuit schematic and completing PCB board;Next the logic design of each module of the digital circuit of FPGA is realized;Then the paper analyzes the characteristics of DDS,putting forward the scheme to reduce the output waveform and analysis of output waveform burr,what's more,the method of eliminating burr is given;Finally,the system testing platform is set up,which tests hardware,the types of the output waveform,the waveform amplitude,the waveform frequency,then testing and analysing the stability of system,to verify the accuracy andpracticability of the design.The advantages and characteristics of this subject is to achieve a virtual instrument,miniaturization,and the use of domestic FPGA and DAC chip B9726 to realize the design,the paper not only can greatly reduce the cost of development,but also to achieve the same function,more important is to can reduce the dependence of foreign related products.This paper realizes the internal logic programming in the FPGA module with Verilog HDL,and completing functional verification online and debugging with simulation software Modelsim and logic analyzer chipscope,using the oscilloscope to generate arbitrary waveform real-time acquisition and analysis.Through the simulation and the actual waveform signal testing,the results meet the expected set of indicators.