核磁共振前置放大器的设计.doc
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核磁共振前置放大器的设计,1.48万字自己原创的毕业论文，仅在本站独家出售，重复率低，推荐下载使用摘要：本文先简要叙述了磁共振的发展史以及磁共振成像技术的基本原理。核磁共振成像技术是80年代发展起来的一种全新的影像检查技术。全称是：核磁共振电子计算机断层扫描。最开始用于磁共振成像的为永磁型低场磁共振，现代mri已发展到3...
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核磁共振前置放大器的设计
1.48万字
自己原创的毕业论文，仅在本站独家出售，重复率低，推荐下载使用
摘要：本文先简要叙述了磁共振的发展史以及磁共振成像技术的基本原理。核磁共振成像技术是80年代发展起来的一种全新的影像检查技术。全称是：核磁共振电子计算机断层扫描。最开始用于磁共振成像的为永磁型低场磁共振，现代MRI已发展到3.0以上，立体三位MRI也已经出现，极大地提高了诊断水平。
然后本文对磁共振成像系统进行简要分析，从射频接收单元引出前置放大器。因为前置放大器所处的特殊位置，本文分析了前置放大器设计过程中应该注意的各种问题，如射频电路中器件的射频特性以及放大器中的噪声和电磁兼容性等。其次论文介绍了自制前置放大器的原理图，并对电路图进行分析，在实际测量中与某公司产品进行对比，得到相应的放大器指标，如增益，通频带，1dB压缩点等。最后，在总结本文的基础上，提出一些这次设计中存在的一些问题以及改进的方向。
关键字：磁共振成像 前置放大器 噪声模型 射频特性
Design of MRI preamplifier
Abstract： This thesis briefly describes the history of MRI and the basic principles of MRI technology.MRI technology whose whole name is NMR computer tomography is a new imaging technology developed in 1980s. At the beginning people use permanent magnet-type low field magnetic resonance. Nowadays,MRI has developed into a modern 3.0 or more, three-dimensional MRI has also emerged, which greatly improved the diagnosis.
Then this paper give a brief analysis of magnetic resonance imaging system and leads out the preamplifier from the RF receiving unit. According to the special position of the preamplifier, then paper analyzes the preamplifier design process should pay attention to a variety of problems, such as radio frequency characteristics of the device and the RF amplifier circuit noise and electromagnetic compatibility. Second, the paper describes the homemade preamplifier schematics, circuit diagrams and analyzed in actual measurement and comparison of a company's products, the corresponding amplifier indicators, such as gain, passband, 1dB compression point and so on. Finally，we summarizing the whole passage and point out some problems，which should be resolved in later works.
Key words：MRI Pre-amplifier Noise model RF characteristics
目 录
第一章 绪论................................................................1
1.1磁共振发展历史........................................................1
1.2低场脉冲磁共振系统基本原理............................................2
1.3 前置放大器概述.......................................................2
1.4本文研究主要内容......................................................3
第二章 磁共振成像设备...................................................4
2.1 磁共振成像系统的组成...............................................4
2.2 磁体子系统.........................................................4
2.3 梯度子系统.........................................................5
2.4 射频子系统.........................................................6
2.5信号采集和图像重建子系统............................................7
2.6 主计算机和图像显示子系统...........................................8
第三章前置放大器主要问题分析..........................................9
3.1 射频电路理论........................................................9
3.1.1 电阻的射频特性.................................................9
3.1.2 电容的射频特性.................................................9
3.1.3 电感的射频特性................................................10
3.2 噪声问题分析........................................................11
3.2.1电路中的噪声源.................................................11
3.2.2放大器的噪声模型...............................................13
3.2.3噪声系数测量...................................................16
3.3 干扰及电磁兼容问题..................................................17
3.3.1 干扰的主要来源.................................................18
3.3.2 电磁干扰的抑制措施.............................................18
3.4 噪声匹配网络........................................................19
第四章低噪声前置放大器设计.............................................21
4.1 前置放大器重要参数...................................................21
4.2 低噪声放大器的设计...................................................23
第五章实测数据与分析....................................................23
5.1测试前网络分析仪校准.................................................24
5.2 实验问题分析........................................................26
致谢........................................................................31
参考文献...................................................................32
1.48万字
自己原创的毕业论文，仅在本站独家出售，重复率低，推荐下载使用
摘要：本文先简要叙述了磁共振的发展史以及磁共振成像技术的基本原理。核磁共振成像技术是80年代发展起来的一种全新的影像检查技术。全称是：核磁共振电子计算机断层扫描。最开始用于磁共振成像的为永磁型低场磁共振，现代MRI已发展到3.0以上，立体三位MRI也已经出现，极大地提高了诊断水平。
然后本文对磁共振成像系统进行简要分析，从射频接收单元引出前置放大器。因为前置放大器所处的特殊位置，本文分析了前置放大器设计过程中应该注意的各种问题，如射频电路中器件的射频特性以及放大器中的噪声和电磁兼容性等。其次论文介绍了自制前置放大器的原理图，并对电路图进行分析，在实际测量中与某公司产品进行对比，得到相应的放大器指标，如增益，通频带，1dB压缩点等。最后，在总结本文的基础上，提出一些这次设计中存在的一些问题以及改进的方向。
关键字：磁共振成像 前置放大器 噪声模型 射频特性
Design of MRI preamplifier
Abstract： This thesis briefly describes the history of MRI and the basic principles of MRI technology.MRI technology whose whole name is NMR computer tomography is a new imaging technology developed in 1980s. At the beginning people use permanent magnet-type low field magnetic resonance. Nowadays,MRI has developed into a modern 3.0 or more, three-dimensional MRI has also emerged, which greatly improved the diagnosis.
Then this paper give a brief analysis of magnetic resonance imaging system and leads out the preamplifier from the RF receiving unit. According to the special position of the preamplifier, then paper analyzes the preamplifier design process should pay attention to a variety of problems, such as radio frequency characteristics of the device and the RF amplifier circuit noise and electromagnetic compatibility. Second, the paper describes the homemade preamplifier schematics, circuit diagrams and analyzed in actual measurement and comparison of a company's products, the corresponding amplifier indicators, such as gain, passband, 1dB compression point and so on. Finally，we summarizing the whole passage and point out some problems，which should be resolved in later works.
Key words：MRI Pre-amplifier Noise model RF characteristics
目 录
第一章 绪论................................................................1
1.1磁共振发展历史........................................................1
1.2低场脉冲磁共振系统基本原理............................................2
1.3 前置放大器概述.......................................................2
1.4本文研究主要内容......................................................3
第二章 磁共振成像设备...................................................4
2.1 磁共振成像系统的组成...............................................4
2.2 磁体子系统.........................................................4
2.3 梯度子系统.........................................................5
2.4 射频子系统.........................................................6
2.5信号采集和图像重建子系统............................................7
2.6 主计算机和图像显示子系统...........................................8
第三章前置放大器主要问题分析..........................................9
3.1 射频电路理论........................................................9
3.1.1 电阻的射频特性.................................................9
3.1.2 电容的射频特性.................................................9
3.1.3 电感的射频特性................................................10
3.2 噪声问题分析........................................................11
3.2.1电路中的噪声源.................................................11
3.2.2放大器的噪声模型...............................................13
3.2.3噪声系数测量...................................................16
3.3 干扰及电磁兼容问题..................................................17
3.3.1 干扰的主要来源.................................................18
3.3.2 电磁干扰的抑制措施.............................................18
3.4 噪声匹配网络........................................................19
第四章低噪声前置放大器设计.............................................21
4.1 前置放大器重要参数...................................................21
4.2 低噪声放大器的设计...................................................23
第五章实测数据与分析....................................................23
5.1测试前网络分析仪校准.................................................24
5.2 实验问题分析........................................................26
致谢........................................................................31
参考文献...................................................................32
