基于DDS信号发生器的杂散研究与设计
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摘要
直接数字式频率合成技术是信号频率合成领域里的一次革命。它在硬件方面具有全数字结构,具有频率转换速度快、频率分辨率高,相位噪声低、频率捷变时相位连续等优点,近十几年来目前,DDS技术已经在雷达、通信和仪器仪表等领域得到广泛应用。受奈奎斯特定理、自身的结构缺陷以及目前数字器件工作速度的限制,DDS的输出频率较低、杂散性能不够理想,这就在一定程度上限制了DDS的应用。
本文对直接数字频率合成技术进行了系统研究,介绍了频率合成技术的发展,分析了DDS的输出频谱特性,通过计算机仿真对相位截位条件下和存在幅度量化误差情况下的频谱特性进行了深入的研究。对数模转换器(DAC)的非理性特性对输出频谱的影响进行了定性分析。在深入研究DDS输出频谱特性的基础上对DDS杂散抑制方法进行了研究,这些方法包括随机扰动技术(包含相位扰动和幅度扰动技术)和ROM压缩技术等。这样就避免了DDS的杂散性能受ROM容量的限制。同时为了得到高纯度的信号,设计了七阶椭圆滤波器来减少杂波,通过对7阶椭圆滤波器特性进行仿真和比较,该滤波器很好的滤除掉20MHz以上的杂波,在软件设计过程中设计了新的数据处理方法很好地兼顾了long型变量处理11字节控制字问题同时也保证了输出信号频谱的纯度。最后结合课题研制了DDS信号产生器控制电路。
总之,DDS是目前所有频率合成方法中比较先进的方法之一,但是它在合成信号的带宽方面还存在固有的缺陷,这限制了它在频率合成领域中更加广泛的使用。本文的最后给出了下一步工作的建议,以期完善频率合成的性能指标。
The invention of Direct Digital Synthesis (DDS) is the revolution of signal frequency synthesis technology. DDS is a wholly digital structure circuit with variousadvantages such as fast frequency switching speed, high frequency resolution, lowphase noise and maintaining constant phase while frequency hopping. In the recent decade, it has been widely used in the fields of radar, communication, apparatus, etc. For the limitation of digital hardware operating speed, Nyquist theorem and DDS structure, the spurious performance of DDS' output is bad and the output frequency can' t reach a high level.
In this dissertation, a systematic research is made on DDS. The development of the frequency synthesis is introduced. The output spectrum of the DDS on the presence of both phase and amplitude truncation is analyzed by computer simulation. An analysis is also made on the effect of the DAC's nonlinearity. Based on analyzing the output spectrum of the DDS, some methods to reduce spurs are proposed. They are modified random dithering and Rom compressing techniques. Then a sine/cosine generator is researched. In this structure, the spurious performance is no longer restricted by the capacity of the ROM. A seven-order ellipse Filter Circuit which reduce the noise of the signal above 20MHz is designed to get little spurs, and desin a new process method to lower the DDS' output spurs which resolve the the problem that process eleven character with the four character variable.
Finally, combined with the practical engineering, the controlling circuit of the low spurs and wideband DDS signal.
All in a word, DDS is one of the most advanced frequency synthesizing techniques, but there are still some disadvantages in using DDS, for example, the narrow bandwidth, which more or less limits its application. In the last part of the thesis, some suggestion are proposed to further improve the result of frequency synthesis.
本文对直接数字频率合成技术进行了系统研究,介绍了频率合成技术的发展,分析了DDS的输出频谱特性,通过计算机仿真对相位截位条件下和存在幅度量化误差情况下的频谱特性进行了深入的研究。对数模转换器(DAC)的非理性特性对输出频谱的影响进行了定性分析。在深入研究DDS输出频谱特性的基础上对DDS杂散抑制方法进行了研究,这些方法包括随机扰动技术(包含相位扰动和幅度扰动技术)和ROM压缩技术等。这样就避免了DDS的杂散性能受ROM容量的限制。同时为了得到高纯度的信号,设计了七阶椭圆滤波器来减少杂波,通过对7阶椭圆滤波器特性进行仿真和比较,该滤波器很好的滤除掉20MHz以上的杂波,在软件设计过程中设计了新的数据处理方法很好地兼顾了long型变量处理11字节控制字问题同时也保证了输出信号频谱的纯度。最后结合课题研制了DDS信号产生器控制电路。
总之,DDS是目前所有频率合成方法中比较先进的方法之一,但是它在合成信号的带宽方面还存在固有的缺陷,这限制了它在频率合成领域中更加广泛的使用。本文的最后给出了下一步工作的建议,以期完善频率合成的性能指标。
The invention of Direct Digital Synthesis (DDS) is the revolution of signal frequency synthesis technology. DDS is a wholly digital structure circuit with variousadvantages such as fast frequency switching speed, high frequency resolution, lowphase noise and maintaining constant phase while frequency hopping. In the recent decade, it has been widely used in the fields of radar, communication, apparatus, etc. For the limitation of digital hardware operating speed, Nyquist theorem and DDS structure, the spurious performance of DDS' output is bad and the output frequency can' t reach a high level.
In this dissertation, a systematic research is made on DDS. The development of the frequency synthesis is introduced. The output spectrum of the DDS on the presence of both phase and amplitude truncation is analyzed by computer simulation. An analysis is also made on the effect of the DAC's nonlinearity. Based on analyzing the output spectrum of the DDS, some methods to reduce spurs are proposed. They are modified random dithering and Rom compressing techniques. Then a sine/cosine generator is researched. In this structure, the spurious performance is no longer restricted by the capacity of the ROM. A seven-order ellipse Filter Circuit which reduce the noise of the signal above 20MHz is designed to get little spurs, and desin a new process method to lower the DDS' output spurs which resolve the the problem that process eleven character with the four character variable.
Finally, combined with the practical engineering, the controlling circuit of the low spurs and wideband DDS signal.
All in a word, DDS is one of the most advanced frequency synthesizing techniques, but there are still some disadvantages in using DDS, for example, the narrow bandwidth, which more or less limits its application. In the last part of the thesis, some suggestion are proposed to further improve the result of frequency synthesis.
引文
[1]王秀杰,张畴先.模拟集成电路.西安:西北工业大学出版社,1996,132-143
[2]张厥盛,曹丽娜.锁相与频率合成技术.成都:电子科技大学出版社,1995
[3]刘光辉.并行DDS频率源技术研究.[电子科技大学硕士论文].成都:电子科技大学无线电物理,2002,11-17
[4]Kenneth A.Essenwanger,Victor S.Reinhardt.Sine output DDS's a survey of the state of the art.IEEE International Frequency Control Symposium.1998:370-378
[5]J.Tiemey,C.Rader,B.Gold.A Digital Frequency Synthesizer.IEEE Transactions on Audio and Electroacoustics,1971.3 AU-19(1):48-57
[6]Nickman L.Direct digital synthesis.Electronics World Wireless World.1992,97(9):746-748
[7]褚人乾,蒋兴才,廖湘平.直接数字式频率合成器(DDS)的频谱特性及其改善方法.通信对抗,1997,10-18
[8]Eisenson H.Frequency synthesis using DDS1NCO technology,a tutorial.IEEE.Electro International Conference Record.Ventura,CA,USA,Electron Conventions Manage,1991,400-418
[9]金数波,邓贤进,王豪才一相位舍位对直接数字频率合成杂散特性的影响.系统工程与电子技术,2002,24(10):16-18
[10]乐翔,秦士.直接数字式合成信号的杂散性能分析.清华大学学报,2000,40(1):46-48
[11]黄蕾,王祝盈,陈小林.DDS系统中实现高精度数据处理的CSl程序设计方法.湖南大学学报,2004.6 31(3):234-237
[12]谢淑如,郑光钦,杨渝生.Protel PCB 99SE电路板设计.北京:清华大学出版社,2002.7,248-250
[13]张玉兴,彭清泉,相位舍位对DDS谱分布的影响.电子科技大学学报,1997,Vol.26,No.4:137-141
[14]冯杰,陈世伟一种抑制DDS相位截断误差引起的杂散的方法.电路与系统学报,1997,Vol.2,No.4:17-21
[15]Analog Device Inc.A Technical Tutorial on Digital Signal Synthesis.1999
[16]M.J.Flanagan and G.A.Zimmerman.Spur-reduced digital Sinusoid Synthesis.IEEE Transactions on communications,Vo1.43,No.7,July1995:2254-2262
[17]Aushkina.High-speed wide band frequency synthesizer.Elektrosvyas,1993(4):38-40
[18]Akihiro Yamagishi.A phase-interpolation direct digital synthesizer with an adaptive integrator.IEEE transactions on microwave theory andtechniques.Vol.48,No.6,2000:905-909
[19]高望.直接数字频率合成技术及其杂散分析.[南京理工大学硕士论文].南京:南京理工大学通信与信息系统,2002,1-5
[20]单鸣,李元,谈宜育.一种减少杂散的直接数字频率合成器改进结构.微电子学,2002.4,32(2):117-119
[21]李宁,王雪.DDS芯片/AD9851在频率合成发生器中的应用.金陵职业大学学报,2001.3 16(1):60-61
[22]M.S.Ohausi,K.R.Laker.现代滤波器设计有源RC和开关电容.刘根泉.第一.北京:科学出版社,1989.2,23-24M版
[23]Kroupa V F.Discrete spurious signals and background noise in direct digital synthesizers.IEEE International frequency Control Symposium.New York,NY,USA,1993:242-250
[24]李季.信号发生器发展浅析田.电子产品世界,2002,10,A:65-75
[25]许慧波,张厥盛.DDS一直接数字式频率合成综述[M].西安.西安电子科技大学出版社,1989
[26]公茂法,马宝甫,孙晨.单片机人机接口实例集[M].北京.北京航空航天大学出版社.1998:7076
[27]王育红,张厥胜.直接数字频率合成器的谱质研究.西安电子科技大学学报.Vol23,No.1,1996
[28]杨华舒,复涛.单片计算机系统抗干扰的软件途径闭.电子技术应用.2001(3)
[29]C.W.Kent,Neng-Huang Sheng.A high purity,high speed direct digital synthesizer.IEEE Proc.47th Annual Frequency Control Symposium,1998
[30]张玉兴.DDS高频高纯频谱频率源技术.系统工程电子技术,1997,No.12:24-28
[31]李衍忠等.DDS谱质分析及其杂散抑制研究综述.现代雷达,2000,No.8:33-38
[32]高泽溪,高成.直接频率合成器(DDS)及其性能分析.北京航空航天大学学报1998,Vol.24,No.5:615-618
[33]赵正敏.相位结尾对DDS输出频谱的分析与计算.东南大学学报,2000,Vol.30.No.1:141-145
[34]韩军功,王家礼.DDS频谱分析及一种新型的改善方法.现代电子技术,2001,(7):45-48
[35]刘铁新,高俊法.一种单片DDS构成的新型频率合成器.宇航计测技术,1999,(8):6-10
[36]肖宏年,朱祥文,刘亚雄.DDS直接数字调制器的原理及应用.湖北工学院学报,1998,24(6):14-18
[37]李春明.数字波形合成技术理论研究与实践.哈尔滨工业大学博士学位论文,1995:19-35
[38]王化深,蒋焕文.直接数字频率合成器的噪声分析.北方交通大学人学学报,1987(4):55-63
[39]胡广书.数字信号处理理论、算法与实现(第二版).清华大学出版社,2003.8
[40]吴国利,汤汉屏.一种抑制DDS杂散的方法.空军电讯工程学院学报,1999,No.2
[41]王幸之等.AT89系列单片机原理与接口技术.北京:北京航空航大大学出版社,2004.5
[42]吴文伟,选择低相位噪声频率合成器的最佳带宽.电信快报,2000(12):25-27
[43]Analog Device Inc.CMOS 180 MHz DDS/DAC Synthesizer AD9851.Technical Datasheet,1999
[44]王伯雄,王雪,陈非凡.工程测试技术.清华大学出版社,2006,1
[2]张厥盛,曹丽娜.锁相与频率合成技术.成都:电子科技大学出版社,1995
[3]刘光辉.并行DDS频率源技术研究.[电子科技大学硕士论文].成都:电子科技大学无线电物理,2002,11-17
[4]Kenneth A.Essenwanger,Victor S.Reinhardt.Sine output DDS's a survey of the state of the art.IEEE International Frequency Control Symposium.1998:370-378
[5]J.Tiemey,C.Rader,B.Gold.A Digital Frequency Synthesizer.IEEE Transactions on Audio and Electroacoustics,1971.3 AU-19(1):48-57
[6]Nickman L.Direct digital synthesis.Electronics World Wireless World.1992,97(9):746-748
[7]褚人乾,蒋兴才,廖湘平.直接数字式频率合成器(DDS)的频谱特性及其改善方法.通信对抗,1997,10-18
[8]Eisenson H.Frequency synthesis using DDS1NCO technology,a tutorial.IEEE.Electro International Conference Record.Ventura,CA,USA,Electron Conventions Manage,1991,400-418
[9]金数波,邓贤进,王豪才一相位舍位对直接数字频率合成杂散特性的影响.系统工程与电子技术,2002,24(10):16-18
[10]乐翔,秦士.直接数字式合成信号的杂散性能分析.清华大学学报,2000,40(1):46-48
[11]黄蕾,王祝盈,陈小林.DDS系统中实现高精度数据处理的CSl程序设计方法.湖南大学学报,2004.6 31(3):234-237
[12]谢淑如,郑光钦,杨渝生.Protel PCB 99SE电路板设计.北京:清华大学出版社,2002.7,248-250
[13]张玉兴,彭清泉,相位舍位对DDS谱分布的影响.电子科技大学学报,1997,Vol.26,No.4:137-141
[14]冯杰,陈世伟一种抑制DDS相位截断误差引起的杂散的方法.电路与系统学报,1997,Vol.2,No.4:17-21
[15]Analog Device Inc.A Technical Tutorial on Digital Signal Synthesis.1999
[16]M.J.Flanagan and G.A.Zimmerman.Spur-reduced digital Sinusoid Synthesis.IEEE Transactions on communications,Vo1.43,No.7,July1995:2254-2262
[17]Aushkina.High-speed wide band frequency synthesizer.Elektrosvyas,1993(4):38-40
[18]Akihiro Yamagishi.A phase-interpolation direct digital synthesizer with an adaptive integrator.IEEE transactions on microwave theory andtechniques.Vol.48,No.6,2000:905-909
[19]高望.直接数字频率合成技术及其杂散分析.[南京理工大学硕士论文].南京:南京理工大学通信与信息系统,2002,1-5
[20]单鸣,李元,谈宜育.一种减少杂散的直接数字频率合成器改进结构.微电子学,2002.4,32(2):117-119
[21]李宁,王雪.DDS芯片/AD9851在频率合成发生器中的应用.金陵职业大学学报,2001.3 16(1):60-61
[22]M.S.Ohausi,K.R.Laker.现代滤波器设计有源RC和开关电容.刘根泉.第一.北京:科学出版社,1989.2,23-24M版
[23]Kroupa V F.Discrete spurious signals and background noise in direct digital synthesizers.IEEE International frequency Control Symposium.New York,NY,USA,1993:242-250
[24]李季.信号发生器发展浅析田.电子产品世界,2002,10,A:65-75
[25]许慧波,张厥盛.DDS一直接数字式频率合成综述[M].西安.西安电子科技大学出版社,1989
[26]公茂法,马宝甫,孙晨.单片机人机接口实例集[M].北京.北京航空航天大学出版社.1998:7076
[27]王育红,张厥胜.直接数字频率合成器的谱质研究.西安电子科技大学学报.Vol23,No.1,1996
[28]杨华舒,复涛.单片计算机系统抗干扰的软件途径闭.电子技术应用.2001(3)
[29]C.W.Kent,Neng-Huang Sheng.A high purity,high speed direct digital synthesizer.IEEE Proc.47th Annual Frequency Control Symposium,1998
[30]张玉兴.DDS高频高纯频谱频率源技术.系统工程电子技术,1997,No.12:24-28
[31]李衍忠等.DDS谱质分析及其杂散抑制研究综述.现代雷达,2000,No.8:33-38
[32]高泽溪,高成.直接频率合成器(DDS)及其性能分析.北京航空航天大学学报1998,Vol.24,No.5:615-618
[33]赵正敏.相位结尾对DDS输出频谱的分析与计算.东南大学学报,2000,Vol.30.No.1:141-145
[34]韩军功,王家礼.DDS频谱分析及一种新型的改善方法.现代电子技术,2001,(7):45-48
[35]刘铁新,高俊法.一种单片DDS构成的新型频率合成器.宇航计测技术,1999,(8):6-10
[36]肖宏年,朱祥文,刘亚雄.DDS直接数字调制器的原理及应用.湖北工学院学报,1998,24(6):14-18
[37]李春明.数字波形合成技术理论研究与实践.哈尔滨工业大学博士学位论文,1995:19-35
[38]王化深,蒋焕文.直接数字频率合成器的噪声分析.北方交通大学人学学报,1987(4):55-63
[39]胡广书.数字信号处理理论、算法与实现(第二版).清华大学出版社,2003.8
[40]吴国利,汤汉屏.一种抑制DDS杂散的方法.空军电讯工程学院学报,1999,No.2
[41]王幸之等.AT89系列单片机原理与接口技术.北京:北京航空航大大学出版社,2004.5
[42]吴文伟,选择低相位噪声频率合成器的最佳带宽.电信快报,2000(12):25-27
[43]Analog Device Inc.CMOS 180 MHz DDS/DAC Synthesizer AD9851.Technical Datasheet,1999
[44]王伯雄,王雪,陈非凡.工程测试技术.清华大学出版社,2006,1