面向EMC的DDS信号及DDS调频信号频谱创新研究
摘要
DDS(直接数字合成)信号和基于DDS的调频信号被广泛用于电子通信设备和电磁兼容测试领域。学位论文第一、二章介绍了DDS技术的特点、典型应用、关键器件,说明了DDS技术的原理,重点分析了DDS信号发生模块中的各个组成部分。
本章第3章和第4章是本学位论文的核心,系统阐述了论文作者在DDS单频率信号和DDS调频(DDFM信号)频谱研究方面的创新成果。
第3章中,分析了“较高频DDS输出”时数模转换器(DAC)的非理想特性,特别是转换(slew time)和闪变(glitch)阶段,建立了波形模型,求得相应的Fourier变换,从而得到新的频谱解析式。试验采用ADI公司的DDS芯片AD9851,测量了信号幅频特性,证明了较以往解析式,新解析式和实测更接近。
第4章中,首次推导得到了余弦调制DDFM信号的频谱解析式,解析式和文献测量结果吻合良好。DDFM与标准FM信号相比,含有谐波分量,基于解析式对此进行了更深入的研究,由于一次谐波是信号失真的重要原因,所以采用数值计算结果函数拟合方法得到了DDFM信号一次谐波失真(FHD)新的近似公式,新公式比文献公式有更好的适用性和精确度。。由于总谐波功率较之一次谐波功率更容易被测量,本章也给出了DDFM总谐波失真THP的仿真结果。不仅如此,该部分首次指出,基于DDS的直接数字调频(DDFM)信号基波内存在失真。基于频谱计算,本章定义了新的失真指标:总基波失真TFD,并且求得了TFD的近似公式,TFD在DDFM信号谐波被抑制的信号发生结构中尤其有意义,我们的研究发现,FHD与常用的一次谐波失真指标TFD的dB值成近似为二分之一比例关系
另一方面,本章仿真研究了ADC与DDS幅度量化效应对DDFM信号频诺杂散的影响,得出了量化杂散影响因素的准定量关系。
第5章是结论和展望,全面总结了学位论文的结论,并且探讨了下一步的研究的两个方向:抑制谐波的滤波器设计研究和调制域抽样理论的深入发展。
在本研究过程中,共发表学术论文(含录用)5篇,参见附录论文列表,若干成果受到了专家的肯定和好评。
DDS signal is widely used in electronic and wireless device, especially in the field of EMC test and measurement .the chapter 1 and 2 of dissertation introduce the features, typical application, key incorporated chip about DDS technology, then introduce the basic principles of DDS, especially the main elements of DDS signal generation structure.
Chapter 3 and 4 is the core of dissertation; expound the innovation research result about the frequency spectrum of DDS and FM signal based on DDS.
In chapter 3, non-ideal characteristics of DAC when "higher frequency DDS signal" is on is analyzed, especially the performance in DAC's Slew stage and Glitch stage, then a waveform model is constructed and it's Fourier transform is got, at last a novel analytical expression of "higher frequency DDS signal" is obtained. The experiment based on DDS IC AD9851 produced by ADI Inc, and amplitude spectrum of DDS signal is measured, demonstrating that compare with former expression, the novel expression fit measurement better.
In chapter 4, this dissertation got analytical expression of spectrum of cosine modulation DDFM signal firstly. Analytical expression fit measurement by former literature well. DDFM signal contains extra harmonics comparing with standard FM signal; harmonics, especially first harmonic is the main factor of distortion of DDFM signal. Based on analytical expression, by the method of function fitting, got new approximate expression of first harmonic distortion (FHD). Compare with former expression, new expression is more precise and more applicable. As total harmonic power THP can be measured more easily than first harmonic power, dissertation THP and its deciding factors, and calculation result is showed. Based on frequency spectrum calculation, a novel measurement of distortion is defined: total fundamental distortion TFD, TFD is useful especially in the DDFM signal generator with harmonics be filtered. This paper point out that TFD is a about half of former measurement: first harmonic distortion FHD.
On the other hand, effects of ADC and the DDS amplitude quantization on the power levels of the spurious spectrum are studied by computer simulation; quasi-quantitative relationship between spurs level and its deciding factors is obtained.
Chapter 5 is about conclusion and prospect. We give a comprehensive summary of dissertation, and discussed the next phase of the study in two directions: the harmonic suppression filter design and modulation domain sampling theory which should be deeply developed.
During the course of the study, were published 5 academic papers (including recruitment), see the Appendix List of papers. Some of innovation achievement is well received by the relevant experts.
本章第3章和第4章是本学位论文的核心,系统阐述了论文作者在DDS单频率信号和DDS调频(DDFM信号)频谱研究方面的创新成果。
第3章中,分析了“较高频DDS输出”时数模转换器(DAC)的非理想特性,特别是转换(slew time)和闪变(glitch)阶段,建立了波形模型,求得相应的Fourier变换,从而得到新的频谱解析式。试验采用ADI公司的DDS芯片AD9851,测量了信号幅频特性,证明了较以往解析式,新解析式和实测更接近。
第4章中,首次推导得到了余弦调制DDFM信号的频谱解析式,解析式和文献测量结果吻合良好。DDFM与标准FM信号相比,含有谐波分量,基于解析式对此进行了更深入的研究,由于一次谐波是信号失真的重要原因,所以采用数值计算结果函数拟合方法得到了DDFM信号一次谐波失真(FHD)新的近似公式,新公式比文献公式有更好的适用性和精确度。。由于总谐波功率较之一次谐波功率更容易被测量,本章也给出了DDFM总谐波失真THP的仿真结果。不仅如此,该部分首次指出,基于DDS的直接数字调频(DDFM)信号基波内存在失真。基于频谱计算,本章定义了新的失真指标:总基波失真TFD,并且求得了TFD的近似公式,TFD在DDFM信号谐波被抑制的信号发生结构中尤其有意义,我们的研究发现,FHD与常用的一次谐波失真指标TFD的dB值成近似为二分之一比例关系
另一方面,本章仿真研究了ADC与DDS幅度量化效应对DDFM信号频诺杂散的影响,得出了量化杂散影响因素的准定量关系。
第5章是结论和展望,全面总结了学位论文的结论,并且探讨了下一步的研究的两个方向:抑制谐波的滤波器设计研究和调制域抽样理论的深入发展。
在本研究过程中,共发表学术论文(含录用)5篇,参见附录论文列表,若干成果受到了专家的肯定和好评。
DDS signal is widely used in electronic and wireless device, especially in the field of EMC test and measurement .the chapter 1 and 2 of dissertation introduce the features, typical application, key incorporated chip about DDS technology, then introduce the basic principles of DDS, especially the main elements of DDS signal generation structure.
Chapter 3 and 4 is the core of dissertation; expound the innovation research result about the frequency spectrum of DDS and FM signal based on DDS.
In chapter 3, non-ideal characteristics of DAC when "higher frequency DDS signal" is on is analyzed, especially the performance in DAC's Slew stage and Glitch stage, then a waveform model is constructed and it's Fourier transform is got, at last a novel analytical expression of "higher frequency DDS signal" is obtained. The experiment based on DDS IC AD9851 produced by ADI Inc, and amplitude spectrum of DDS signal is measured, demonstrating that compare with former expression, the novel expression fit measurement better.
In chapter 4, this dissertation got analytical expression of spectrum of cosine modulation DDFM signal firstly. Analytical expression fit measurement by former literature well. DDFM signal contains extra harmonics comparing with standard FM signal; harmonics, especially first harmonic is the main factor of distortion of DDFM signal. Based on analytical expression, by the method of function fitting, got new approximate expression of first harmonic distortion (FHD). Compare with former expression, new expression is more precise and more applicable. As total harmonic power THP can be measured more easily than first harmonic power, dissertation THP and its deciding factors, and calculation result is showed. Based on frequency spectrum calculation, a novel measurement of distortion is defined: total fundamental distortion TFD, TFD is useful especially in the DDFM signal generator with harmonics be filtered. This paper point out that TFD is a about half of former measurement: first harmonic distortion FHD.
On the other hand, effects of ADC and the DDS amplitude quantization on the power levels of the spurious spectrum are studied by computer simulation; quasi-quantitative relationship between spurs level and its deciding factors is obtained.
Chapter 5 is about conclusion and prospect. We give a comprehensive summary of dissertation, and discussed the next phase of the study in two directions: the harmonic suppression filter design and modulation domain sampling theory which should be deeply developed.
During the course of the study, were published 5 academic papers (including recruitment), see the Appendix List of papers. Some of innovation achievement is well received by the relevant experts.
引文
[1]J.B.Dominguez and J.M.Riera Sails,"PM and FM generation with DDS:Effects of sampling the modulating signai'[J].Electronics Letters,vol.31,no.7,March 30,1995.p516-517
[2]王秋生,王祁,孙圣和.直接数字合成调频信号的研究[J].仪器仪表学报,2000年,第21卷第4期:p428-431.
[3]宋跃,张小平,周明辉,DDS时域参数分析及优化研究[J].电子测量与仪器学报,2006,第20卷第1期:p60-63.
[4]王建新,刘国岁,朱伟强,一种DDS/PLL混合型高分辨率频率合成器[J].电子测量与仪器学报,1999,第13卷第4期:p72-75.
[5]田新广,张尔扬,邬书跃.DDS幅度量化杂散信号的频谱研究[J].通信学报,2003,第24卷第7期:p79-85.
[6]霍志勇,张军.DDS线性调频信号产生技术研究[J].无线电工程,2006年,第36卷第1期:p27-29
[7]王秋生,王祁,孙圣和.直接数字合成调频信号的研究[J].仪器仪表学报,第21卷第4期:p428-431.
[8]田书林,刘科,周鹏.基于双DDS的高速任意波发生器实现技术[J].仪器仪表学报,第25卷第4期:p557-560
[9]董国伟,李秋明,赵强,顾德英,汪晋宽.基于FPGA的直接数字频率合成器的设计[J].仪器仪表学报,第27卷第6期增刊:p877-879.
[10]G.-J.van Rooyen and J.G Lourens.A Quadrature Baseband Approach to Direct Digital FM Synthesis[J],IEEE Transactions on Broadcasting,Vol.46,NO.3:p227-230.September 2000
[11]张若禹,杨文革,孙静.DDS频谱分析与杂散预测软件包[J],装备指挥技术学院学报,2005年8月,第16卷第4期:p91-94
[12]E.R.Twitchell,"A digital approach to an FM exciter," IEEE Transactions on Broadcasting,vol.38,no.2,pp.106-109,June 1992.
[13]章小梅,姜茂仁,费元春.基于DDS的宽带线性调频源中椭圆低通滤波器设计[J].青岛大学学报(工程技术版).2006年9月,第21卷第3期.p46-49
[14]刘朝军,许人灿,陈曾平,DDS输出信号频谱结构的系统分析,国防科技大学学报,2005年第27卷第6期:p53-56
[15]费元春,苏广川,等.宽带雷达信号产生技术[M].北京:国防工业出版社,2002.
[16]Tmery J.A.Digital frequency synthesizer[J].IEEE Trans.1971,AE-19(l):p48-57.
[17]张玉兴,彭清泉.相位舍位对DDS谱分布的影响[J].电子科技大学学报,1997,1997,26(2):p137-142.
[18]张玉兴,彭清泉.DDS的背景杂散信号分析[J].电子科技大学学报,1997,1997,26(2):p137-142
[19]许碧荣,基于DSP Builder的DDS信号源设计,中国电子科学研究院学报[J],2006年第5期,p468-471.
[20]Walt Kester,Evaluating High Speed DAC Performance[Online],www.analog.com,2005.
[21]J.Vandenbussche,G.V.der Plas,G.Gielen,and W.Sansen.Behavioral model of reusable D/A converters[J].IEEE Trans.Circuits Syst.Ⅱ,Analog.Digit.Signal Process.vol.46,no.10,pp.1323-1326,Oct.1999.
[22]IC datasheet of AD9851,Analog Devices Inc.2003.
[2]王秋生,王祁,孙圣和.直接数字合成调频信号的研究[J].仪器仪表学报,2000年,第21卷第4期:p428-431.
[3]宋跃,张小平,周明辉,DDS时域参数分析及优化研究[J].电子测量与仪器学报,2006,第20卷第1期:p60-63.
[4]王建新,刘国岁,朱伟强,一种DDS/PLL混合型高分辨率频率合成器[J].电子测量与仪器学报,1999,第13卷第4期:p72-75.
[5]田新广,张尔扬,邬书跃.DDS幅度量化杂散信号的频谱研究[J].通信学报,2003,第24卷第7期:p79-85.
[6]霍志勇,张军.DDS线性调频信号产生技术研究[J].无线电工程,2006年,第36卷第1期:p27-29
[7]王秋生,王祁,孙圣和.直接数字合成调频信号的研究[J].仪器仪表学报,第21卷第4期:p428-431.
[8]田书林,刘科,周鹏.基于双DDS的高速任意波发生器实现技术[J].仪器仪表学报,第25卷第4期:p557-560
[9]董国伟,李秋明,赵强,顾德英,汪晋宽.基于FPGA的直接数字频率合成器的设计[J].仪器仪表学报,第27卷第6期增刊:p877-879.
[10]G.-J.van Rooyen and J.G Lourens.A Quadrature Baseband Approach to Direct Digital FM Synthesis[J],IEEE Transactions on Broadcasting,Vol.46,NO.3:p227-230.September 2000
[11]张若禹,杨文革,孙静.DDS频谱分析与杂散预测软件包[J],装备指挥技术学院学报,2005年8月,第16卷第4期:p91-94
[12]E.R.Twitchell,"A digital approach to an FM exciter," IEEE Transactions on Broadcasting,vol.38,no.2,pp.106-109,June 1992.
[13]章小梅,姜茂仁,费元春.基于DDS的宽带线性调频源中椭圆低通滤波器设计[J].青岛大学学报(工程技术版).2006年9月,第21卷第3期.p46-49
[14]刘朝军,许人灿,陈曾平,DDS输出信号频谱结构的系统分析,国防科技大学学报,2005年第27卷第6期:p53-56
[15]费元春,苏广川,等.宽带雷达信号产生技术[M].北京:国防工业出版社,2002.
[16]Tmery J.A.Digital frequency synthesizer[J].IEEE Trans.1971,AE-19(l):p48-57.
[17]张玉兴,彭清泉.相位舍位对DDS谱分布的影响[J].电子科技大学学报,1997,1997,26(2):p137-142.
[18]张玉兴,彭清泉.DDS的背景杂散信号分析[J].电子科技大学学报,1997,1997,26(2):p137-142
[19]许碧荣,基于DSP Builder的DDS信号源设计,中国电子科学研究院学报[J],2006年第5期,p468-471.
[20]Walt Kester,Evaluating High Speed DAC Performance[Online],www.analog.com,2005.
[21]J.Vandenbussche,G.V.der Plas,G.Gielen,and W.Sansen.Behavioral model of reusable D/A converters[J].IEEE Trans.Circuits Syst.Ⅱ,Analog.Digit.Signal Process.vol.46,no.10,pp.1323-1326,Oct.1999.
[22]IC datasheet of AD9851,Analog Devices Inc.2003.