The Design Of The High-performance Arbitrary Waveform Generator

Signal source is an indispensable tool in electric measures and scientific research and widely used in the field, such as instrument, communication, radar and controllers. Therefore, a high-performance signal source is becoming more and more important. Direct Digital Synthesis is a completely new digitized frequency synthesis technology. Due to its high frequency resolution and rapid frequency changing rate as well as diverse waveforms, it is widely applied to high-performance signal sources designs.In this paper, the author uses FPGA and high speed DAC to implement the research of arbitrary waveform generator.Its sampling rate is500MSa/s, the analog bandwidth is160MHz, which is a typical high-speed mixed-signal circuit system. In the high-speed circuit design, interconnections are no longer transparent to signals. If not properly approached, a series of problems will appear, such as reflection, crosstalk, ground, attenuation, etc. These problems can seriously affect the signal quality, and even lead to circuit malfunctions. In high-speed mixed-signal circuits, we have to deal with not only the signal integrity, but also the mutual interference between the digital circuits and analog circuits.First,the paper introduces the principles of DDS and the advantages of FPGA to implement DDS arbitrary waveform generator.Then it concretely describes the design scheme, circuit structure, chip selection, design of signal processing of how to use FPGA to implement DDS arbitrary waveform generator. The system work flow is introduced in detail as well. It also concretely discusses the probable problems of signal integrity and makes use of HyperLynx of Mentor to simulate the reflection and crosstalk. According to the simulation results, the author makes relevant rules of layout and wiring to complete the PCB design.In the end, the thesis shows the tested data of the system. The outcome of the test indicates feasibility to achieve DDS arbitrary waveform generator by using FPGA. The analog bandwidth of it can be up to160MHz. It stably outputs32kinds of arbitrary waveforms, such as sine waveforms, pulse waveforms, index waveforms and etc.