ADS高低阻抗线微带滤波器设计-Lec06
基于ADS的微带线带通滤波器设计
基于ADS的微带线带通滤波器设计摘要：该文章讨论的是基于ADS软件的平行耦合微带线带通滤波器的设计过程。
利用集总参数低通原型滤波器经过一系列转化可以得到微带线带通滤波器的特性，运用传输线原理和导纳变换公式获得带通滤波器的相关参数，并借助功能强大的ADS软件对微带线带通滤波器的原理图和版图进行设计制作。
该软件只需要输入相应的原始数据，便可方便得到频率响应等相关特性。
我们也可以借助ADS软件对其进行优化仿真，以得到更加优质的带通滤波器。
关键词：带通滤波器；微带线；传输线；ADS1.引言随着近年来无线通信技术的迅猛发展，微波滤波器已经成为作为辨别分离有用和无用资源的重要部件，并大量使用于通信系统领域，其性能的优越直接影响整个通信系统的质量。
现代通信对微波滤波器的整体要求越来越高，以求得到更加微小化、轻量化、集成化的高性能低成本的滤波器。
本文设计运用微带滤波器印刷电路的方法，可以满足尺寸小、成本低且性能稳定的要求，被广泛运用于无线通信系统中。
目前在无线通信系统领域中，微波滤波器的种类日益增多，性能和设计方法各有差异。
但总体来看，微波滤波器的设计大都采用从集总参数的低通原型滤波器出发经过一系列变换得到的。
本章讨论的是平行耦合微带线带通滤波器的设计，它同样是基于集总参数低通原型滤波器出发，经过等效变换可以得到与带通滤波器相应的低通原型模型，再经过阻抗倒置变换或导纳变换便可以得到相应的带通滤波器的设计模型及相关参数。
本文首先介绍微带线带通滤波器的设计原理，然后根据基本原理推导出滤波器的相关参数，再运用ADS软件进行制作、优化和仿真，最后将完整的设计图纸和相关参数拿到工厂加工制成成品。
为了验证该微带线带通滤波器的设计和仿真的正确性，本文采用网络分析仪对该滤波器进行了相关测试，测试结果和仿真效果相吻合。
2.微带线带通滤波器的设计原理及设计过程根据滤波器综合理论，低通原型滤波器是设计其他滤波器的基础。
本文设计的带通滤波器同样是在低通原型滤波器的基础上经过变换得到的。
2024版ADS设计实验教程微波滤波器的设计制作与调试
•引言•微波滤波器基本原理•ADS 软件在微波滤波器设计中的应用•微波滤波器制作工艺流程•调试技巧与常见问题解决方案•实验案例分析与讨论•总结与展望目录01引言微波滤波器概述微波滤波器是一种用于控制微波频率响应的二端口网络，广泛应用于无线通信、雷达、卫星通信等领域。
微波滤波器的主要功能是允许特定频率范围内的信号通过，同时抑制其他频率范围的信号，从而实现信号的选频和滤波。
微波滤波器的性能指标包括插入损耗、带宽、带内波动、带外抑制等，这些指标直接影响着通信系统的性能。
设计制作与调试重要性设计是微波滤波器制作的首要环节，良好的设计能够确保滤波器的性能指标满足系统要求。
制作是将设计转化为实物的过程，制作精度和质量直接影响着滤波器的最终性能。
调试是对制作完成的滤波器进行性能调整和优化，使其达到最佳工作状态的过程。
本教程旨在介绍微波滤波器的设计、制作与调试过程，帮助读者掌握相关知识和技能。
教程内容包括微波滤波器的基本原理、设计方法、制作流程和调试技巧等。
通过本教程的学习，读者将能够独立完成微波滤波器的设计、制作与调试，为实际工程应用打下基础。
教程目的和内容02微波滤波器基本原理低通滤波器高通滤波器带通滤波器带阻滤波器微波滤波器分类工作原理及性能指标工作原理性能指标常见类型微波滤波器特点集总参数滤波器分布参数滤波器陶瓷滤波器晶体滤波器03ADS软件在微波滤波器设计中的应用ADS软件简介及功能模块ADS（Advanced Design System）是一款领先的电子设计自动化软件，广泛应用于微波、射频和高速数字电路的设计、仿真与优化。
ADS软件包含多个功能模块，如原理图设计、版图设计、电磁仿真、系统级仿真等，可满足不同设计阶段的需求。
ADS软件支持多种微波滤波器类型的设计，如低通、高通、带通、带阻等，具有强大的设计能力和灵活性。
微波滤波器设计流程确定滤波器类型和性能指标根据实际需求选择合适的滤波器类型，并确定滤波器的性能指标，如中心频率、带宽、插入损耗、带外抑制等。
ADS微带滤波器设计方法PPT课件
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进行参数优化（续）
经过数次优化后，CurrentEf的值为0，即为优化 结束。优化过程中根据情况可能会对优化目标、 优化变量的取值范围、优化方法及次数进行适当 的调整。
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优化目标的设置（续）
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进行参数优化
设置完优化目标后最好先把原理图存储一下，然后就可 以进行参数优化了。
点击工具栏中的Simulate 按钮就开始进行优化仿真 了。在优化过程中会打开一个状态窗口显示优化的结果 (见下页图)，其中的CurrentEF表示与优化目标的偏差， 数值越小表示越接近优化目标，0表示达到了优化目标， 下面还列出了各优化变量的值，当优化结束时还会打开 图形显示窗口。
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观察仿真曲线
优化完成后必须关掉优化控件，才能观察仿真的曲线。 方法是点击原理图工具栏中的 按钮，然后点击优 化控件OPTIM，则控件上打了红叉表示已经被关掉。
要想使控件重新开启，只需点击工具栏中的 按钮， 然后点击要开启的控件，则控件上的红叉消失，功能 也重新恢复了。
对于原理图上其他的部件，如果想使其关 闭或开启，也可以采取同样的方法。
点击Length Unit设置长度单位为毫米
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创建新的工程文件（续）
工程文件创建完毕后主窗口变为下图
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创建新的工程文件（续）
同时原理图设计窗口打开
《ADS设计滤波器》课件
重新仿真
进行二次仿真以验证调整后的电 路性能ຫໍສະໝຸດ ADS设计滤波器的注意事项
元器件的选择要合理
根据设计需求选择适合的元器件
仿真设置要正确
准确设置仿真参数，以获取准确的仿真结 果
连接要准确
确保元器件之间的连接正确无误
调整参数要谨慎
在调整元器件参数时要小心谨慎，避免影 响整体电路性能
ADS设计滤波器的示例
2 高通滤波器 4 带阻滤波器
ADS设计滤波器的流程
1
新建Schematic
创建电路原理图
选择合适的元器件
2
根据设计需求选择合适的电子元
器件
3
连接元器件
将元器件正确连接成电路
添加控制器和仿真设置
4
配置控制器以及设置仿真参数
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进行仿真
运行仿真并观察电路性能
调整元器件参数
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根据仿真结果调整元器件参数
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低通滤波器的设计
设计一个低通滤波器来滤除 高频噪声
带通滤波器的设计
设计一个带通滤波器来提取 特定频率范围内的信号
带阻滤波器的设计
设计一个带阻滤波器来抑制 特定频率范围内的信号
总结
1 ADS是RF、微波电路设计的重要工具 2 滤波器在通信、雷达等领域有广泛应用 3 ADS设计滤波器要注意元器件的选择和仿真设置的正确处理
《ADS设计滤波器》PPT 课件
# ADS设计滤波器
什么是ADS？
ADS是高级设计系统（Advanced Design System）的简称，用于RF、微波电路的 设计和仿真。
滤波器的作用
1 抑制不需要的信号，保留有用信号 2 在通信、雷达等领域有广泛应用
ADS低通滤波器设计PPT课件
滤波器原理图设计-----画微带线原理图
MLIN选项在左边Palette的TLines-Microstrip中
滤波器原理图设计-----电路参数设置
添加MSUB控件，双击添加参数 H:基板厚度(1.58mm) Er:基板相对介电常数(4.2) Mur:相对磁导率(1) Coud:金属电导率(5.88e7) Hu:封装高度(1.0e33mm) T:金属层厚度(0.035mm) TanD:损耗角正切(0.02) Rough:表面粗糙度(0mm)
滤波器原理图设计-----最终电路图
滤波器原理图设计-----优化仿真
点击优化图标 ，进行优化 稍待片刻即可查看效果
滤波器原理图设计-----优化仿真
然后点击update design 最终参数：
w0 = 2.77887 w1 = 12.6961 w2 = 424.403e-03 w3 = 10.1017 w4 = 475.833e-03 w5 = 10.12 w6 = 358.642e-03
点击 ，设置为
微带滤波器版图生成-----EM仿真
点击simulate，静待几分钟仿真出来的传输特性 出现这个是license的问题，去/thread-471722-1-1.html下载补丁
微带滤波器版图生成-----EM仿真
结论
观察得之滤波器在通带内（0~2.5GHz）插入损耗小于3.439dB，在4~5GHz之间大于28.096dB，满足设计要求
7
0.517
120
12.3
0.391252
2.45949
8
1
50
90
3.11445
16.7722
滤波器原理图设计-----添加变量
用LineCalc计算八段微带线的长和宽后我们要将各个数据添加到变量控件VAR中。 选择Insert->VAR在原理图中添加VAR然后双击，在“Name”文本框中输入变量的名称，“Variable Value”文本框中输入变量的初值，单机【ADD】添加变量 然后单击【Tune/Opt/Stat/Doe..】按钮打开参数优化对话框设置变量的取值范围，选择“Optimation”标签页。其中，“Enable/Disabled”表示该变量是否能被优化，“Minimum Value”表示可优化的最小值，“Maximum Value”表示可优化的最大值
ADS微带滤波器设计方法课件
进行参数优化
通过调整滤波器参数，如电感、 电容、长度、宽度等，对滤波 器性能进行优化。
进行仿真验证
通过仿真软件对所设计的滤波 器进行性能验证，确保满足设 计要求。
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ADS微带滤波器设计实践
建立设计工程
确定设计目标
明确滤波器的性能指标，如通带范围、 阻带范围、插入损耗等。
选择合适的微带线结构
设定工作频率和介质参数
根据设计目标和工作频率，设定合适 的介质参数，如厚度、相对介电常数 等。
根据设计需求，选择合适的微带线结 构，如平行耦合线、发卡型等。
参数设置与优化
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02
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调整耦合系数
通过调整微带线间的距离、 宽度等参数，优化耦合系 数，以实现理想的滤波器 性能。
优化谐振器长度
调整谐振器的长度，以实 现所需的频率响应。
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ADS微带滤波器设计基础
微带线理论
微带线定义
01
微带线是一种传输线，它由一个介质基片上的一条金属导带和
两条金属接地边构成。
微带线特性
02
微带线具有低阻抗、高共模抑制比、低辐射等特性，广泛应用
于微波和毫米波频段的电路设计中。
微带线传输模式
03
微带线主要传输准TEM模，即电场和磁场分量在传输方向上为
ADS软件介绍
ADS（Advanced Design System） 是一款微波电路和系统设计软件，由 美国安捷伦公司开发，提供了从电路 设计、仿真、版图绘制到系统仿真的 全流程解决方案。
ADS软件具有友好的用户界面和强大 的功能模块，支持多种设计工具和第 三方软件接口，广泛应用于通信、雷 达、电子战等领域的电路和系统设计。
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ADS微带滤波器设计方法PPT课件
文档仅供参考，如有不当之处，请联系本人改正。
优化目标的设置
在原理图设计窗口中选择优化 工具栏
选择优化设置控件 放置在原 理图中，双击该控件设置优化 方法及优化次数。
常用的优化方法有Random(随机)、 Gradient(梯度)等。
随机法通常用于大范围搜索，梯 度法则用于局部收敛
文档仅供参考，如有不当之处，请联系本人改正。
选择Term 放置在滤波器两边，用来定义端 口1和2，点击 图标，放置两个地，并按照 下页图连接好电路。
选择S参数扫描控件 放置在原理图中，并设 置扫描的频率范围和步长，频率范围根据滤波 器的指标确定(要包含通带和阻带的频率范围)。
文档仅供参考，如有不当之处，请联系本人改正。
S参数仿真电路设置（续）
响系统的前后级匹配，使系统性能下降。
文档仅供参考，如有不当之处，请联系本人改正。
生成滤波器的原理图
在原理图设计窗口中选择微带电路的工具 栏
窗口左侧的工具栏变为右图所示 在工具栏中点击选择耦合线Mcfil
并在右侧的绘图区放置 选择微带线MLIN 以及控件
MSUB 分别放置在绘图区中 选择画线工具 将电路连接好，
微带线计算工具（续）
另外打开的一个窗口显示当前运算状态以及错 误信息。
文档仅供参考，如有不当之处，请联系本人改正。
设置微带器件的参数
双击两边的引出线TL1、TL2，分别将其宽与长设为1.52 mm和2.5 mm(其中线长只是暂定，以后制作版图时还会修 改)。
平行耦合线滤波器的结构是对称的，所以五个耦合线节中， 第1、5及2、4节微带线长L、宽W和缝隙S的尺寸是相同的。 耦合线的这些参数是滤波器设计和优化的主要参数，因此 要用变量代替，便于后面修改和优化。
基于ADS的微带高低阻抗线低通滤波器的优化设计
式中 Z h 为高阻抗线值， zl 为低阻抗值，vh =c 是空气中光速，
vl =
1 。 c 是介质中的光速。 1 Yl = ， Yh = Z Z εr h l
5.根据滤波器的实际元件数值和边缘电容值，根据公式 （7） 、 （8）计算出各高低阻抗线的长度尺寸。 6.得出了传输线各短尺寸后，低通滤波器基本上设计完 毕，但最后必须考虑下寄生通带的问题。当传输线尺寸远小 于波长时，才维持其半集总参数的性质，此时得到的低通滤 波器特性才基本上和低通原型滤波器特性相仿；而当工作频 率远高于截止频率时，相应的滤波特性也不再和原型滤波器
（三）微带低通滤波器设计步骤
图 1 微带低通滤波器原型 其中 R 是电源内阻，Rn+1 是负载电阻。通常情况下，微 波滤波器的电源和传输线是匹配的，即 R= Z 0 。根据设计方法 的不同（通常是按最大平坦度特性或者契比雪夫特性设计） ， 将其衰减多项式和 L、C 梯形的衰减特性多项式逐项进行比较 系数，即可得出个元件归一化数值。具体设计是可查阅滤波 器设计手册。 1.给出初始数据为电源内阻 Z 0 、截止频率ω1、截止频率 时的衰减或者通带内的纹波，以及通带外衰减上升坡度。根 据给定的带外衰减及带外上升坡度的要求，决定滤波器的最 少节数。 2.根据节数 n， 通过查表得到低通原型滤波器归一化元件 参量数值表中找出各节元件参量值。 3.根据给出的内阻及截止频率值，应用公式（4） 、 （5） 、 （6）将原型表中的归一化元件值转化为实际滤波器的元件 值。
（一）引言
进入21世纪，人类进入了信息时代，对信息的价值越来 越重视，对通信的要求越来越高，各种通信系统相继发展起 来。与此同时，信号频域变得越来越拥挤，各种频段的通信 系统相继出现，为了避免这个频段间的串扰，高质量滤波器 是通信系统中必不可少的部件，当频率达到微波波段后，集 总元件实现滤波就变得不现实。为了实现对无线通信系统频 率的选择性，抑制不需要频率成分，并将需要的成分无损耗 传输的任务，微波滤波器起到了至关重要的作用。为了让主 频无损耗传输，干扰尽可能的抑制，微波滤波器的性能，很 大程度上决定信号的质量，直接影响到系统的性能。基于微 带滤波器结构简单、易加工等优点，微带滤波器的研究与设 计显得尤为重要。本文采用微带滤波器中比较成熟的高低阻 抗线结构，仿真并优化了一个截止频率（2.5GHz）处于S波段 的低通滤波器。
微带线带通滤波器ADS设计
应用ADS设计微带线带通滤波器1、微带带通微带线地基本知识微波带通滤波器是应用广泛、结构类型繁多地微波滤波器,但适合微带结构地带通滤波器结构就不是那么多了,这是由于微带线本身地局限性,因为微带结构是个平面电路,中心导带必须制作在一个平面基片上,这样所有地具有串联短截线地滤波器都不能用微带结构来实现；其次在微带结构中短路端不易实现和精确控制,因而所有具有短路短截线和谐振器地滤波器也不太适合于微带结构.b5E2RGbCAP 微带线带通滤波器地电路结构地主要形式有5种：1、电容间隙耦合滤波器带宽较窄,在微波低端上显得太长,不够紧凑,在2GHz以上有辐射损耗.2、平行耦合微带线带通滤波器窄带滤波器,有5％到25％地相对带宽,能够精确设计,常为人们所乐用.但其在微波低端显得过长,结构不够紧凑；在频带较宽时耦合间隙较小,实现比较困难.p1EanqFDPw3、发夹线带通滤波器把耦合微带线谐振器折迭成发夹形式而成.这种滤波器由于容易激起表面波,性能不够理想,故常把它与耦合谐振器混合来用,以防止表面波地直接耦合.这种滤波器地精确设计较难.DXDiTa9E3d4、1/4波长短路短截线滤波器5、半波长开路短截线滤波器下面主要介绍平行耦合微带线带通滤波器地设计,这里只对其整个设计过程和方法进行简单地介绍.2、平行耦合线微带带通滤波器平行耦合线微带带通滤波器是由几节半波长谐振器组合而成地,它不要求对地连接,结构简单,易于实现,是一种应用广泛地滤波器.整个电路可以印制在很薄地介质基片上(可以簿到1mm以下>,故其横截面尺寸比波导、同轴线结构地小得多；其纵向尺寸虽和工作波长可以比拟,但采用高介电常数地介质基片,使线上地波长比自由空间小了几倍,同样可以减小；此外,整个微带电路元件共用接地板,只需由导体带条构成电路图形,结构大为紧凑,从而大大减小了体积和重量.RTCrpUDGiT关于平行耦合线微带带通滤波器地设计方法,已有不少资料予以介绍.但是,在设计过程中发现,到目前为止所查阅到地各种文献,还没有一种能够做到准确设计.在经典地工程设计中,为避免繁杂地运算,一般只采用简化公式并查阅图表,这就造成较大地误差.而使用电子计算机进行辅助设计时,则可以力求数学模型精确,而不追求过分地简化.基于实际设计地需要,我对于平行耦合线微带带通滤波器地准确设计进行研究,编制了计算机辅助设计地小程序<附上）,并利用CAD软件设计了微带带通滤波器,仿真模拟效果令人满意.应用此程序,不仅使设计速度大为提高,而且大大提高了设计地准确性.5PCzVD7HxA设计原理图1为平行耦合线微带带通滤波器地电路结构示意图.它有n个谐振器(对应于滤波器地阶数n>,每个谐振器长为半波长(对应中心频率>,由n＋1个平行耦合线节组成,长为四分之一波长(对应中心频率>.图2为一节平行耦合线及他地等效电路,其中Z0e－Z0o＝2Z0；Z0e*Z0o=Z02.jLBHrnAILg图2 平行耦合线节及其等效电路平行耦合线微带带通滤波器地设计可分为以下几个步骤进行：第一步：由给定地通带和阻带衰减特性,用低通到带通地频率变换式(1>,选出合适地归一化低通原型,计算出滤波器地阶数,得到归一化低通原型地元件值<这一部分地计算可以查表得之）；xHAQX74J0X第二步：用网络等效方法,计算各级奇、偶模阻抗；第三步：由各级奇、偶模阻抗,综合出微带线结构尺寸<这一个部分用PUFF实现）.$4.2.2计算公式本文所述地设计方法,用到地公式很多,有些公式如最大平坦特性与切比雪夫特性滤波器归一化低通原型地阶数及元件值地计算公式及很多图表,很多书中都有说明,这里就不再介绍,查阅公式和图表请参阅参考书目,那里有很详尽地公式及图表介绍.在此首先给出由低通到带通地频率变化式；接着给出由低通原型元件值到奇、偶模特性阻抗地计算式.LDAYtRyKfE1、由低通到带通地频率变换上式中,为低通原型地频率变量,是低通原型地截止频率,是带通滤波器地带边频率,是带通滤波器地频率变量,是带通滤波器地中心频率,是带通滤波器地相对带宽,它按下式计算：Zzz6ZB2Ltk1、耦合线节地奇、偶模阻抗设滤波器地节数为n,归一化低通原型地元件值为g0,g1,g2……gn+1,则有以下设计公式：( 3 >(j=1,2,…,n-1> ( 4 >( 5 >其中,Y0为传输线特性导纳,J代表导纳倒置转换器,其余参数W、同(1>这样,我们可以得第J个耦合线节地奇模阻抗和精模阻抗分别为：2、由各级奇、偶模阻抗综合出微带线结构尺寸这部分公式繁多,计算麻烦,本文应用PUFF软件自动计算出平行耦合线地各参数值.$4.2.3 滤波器地理论设计设计指标：中心频率f0：2.45GHz；带宽BW：100～200MHz<这里理论计算采用100MHz）；输入、输出地特征阻抗均为50Ω；在f＝2.15GHz上衰减46dB；选用纹波系数为0.01dB地切比雪夫原型.<1）、设计低通原型由公式(1>计算地＝6,则查图表得知阶数n＝3,再次查找纹波系数为0.01dB地切比雪夫原型地元件数值表地：g0＝1,g1＝0.6292,g2＝0.9703,g3＝0.6292,g4＝1,＝1.<2）、计算导纳变换器地归一导纳由公式( 3 >、( 4 >、( 5 >计算得：＝0.316,＝0.08,＝0.08,＝0.316.<3）、计算各平行耦合线节地奇模和偶模地阻抗由公式( 6 >、( 7 >计算得：( Z0e >01=( Z0e >34=50*(1+0.316+0.316*0.316>=70.7928Ω；dvzfvkwMI1( Z0o >01=( Z0o >34=50*(1-0.316+0.316*0.316>=39.1928Ω；rqyn14ZNXI( Z0e >12＝( Z0e >23＝54.32Ω；( Z0o >12＝( Z0o >23＝46.32Ω；<4）、计算平行耦合线节地W、S和L这部分计算由PUFF完成：在PUFF界面按F3,激活F3窗口,设置里面地数值为：“a clines 71Ω 39Ω90°”表示a是理想双传输线,长度为四分之一波长,偶模阻抗为71Ω,奇模阻抗为39Ω；EmxvxOtOco“b clines 54Ω 46Ω 90°”表示b是理想双传输线,长度为四分之一波长,偶模阻抗为54Ω,奇模阻抗为46Ω；SixE2yXPq5<其奇偶模得阻值由前面计算所得,其计算带宽为100MHz.）把光标移到a,安下“＝”键,即得该传输线得参数值：L=12.523mm,W=0.846mm,S=0.292mm。
11.1.1 微带阶梯阻抗低通滤波器的理论基础[共2页]
![11.1.1 微带阶梯阻抗低通滤波器的理论基础[共2页]](https://img.taocdn.com/s3/m/fe8b6cbf7e21af45b207a8a6.png)
第11章分布参数低通滤波器的仿真
当频率不高时，集总元器件滤波器工作良好，但当频率达到或接
近GHz时，滤波器通常由分布参数元器件构成，这是由于两个原因造
成的，其一是频率高时电感和电容应选的元器件值过小，由于寄生参
数的影响，如此小的电感和电容已经不能再使用集总参数元器件；其
二是此时工作波长与滤波器元器件的物理尺寸相近，滤波器元器件之
间的距离不可忽视，需要考虑分布参数效应。
本章讨论由分布参数构成的低通滤波器，分布参数低通滤波器
可以由阶梯阻抗低通滤波器或短截线低通滤波器实现，本章主要介
绍利用ADS软件设计分布参数低通滤波器的方法。
本章将首先给出
分布参数低通滤波器的理论基础，然后讨论如何利用ADS软件设计、
仿真、调谐与优化分布参数低通滤波器，针对微带线阶梯阻抗低通
滤波器和短截线低通滤波器，本章将完成符合技术指标的滤波器原
理图和布局图。
11.1 微带阶梯阻抗低通滤波器的仿真
阶梯阻抗低通滤波器也称为高低阻抗低通滤波器，它是一种结构简洁的电路，其由很高和很低特性阻抗的传输线段交替排列而成，结构紧凑，便于设计和实现。
本节将给出符合技术指标的微带线阶梯阻抗低通滤波器原理图，并由原理图给出阶梯阻抗低通滤波器版图。
11.1.1 微带阶梯阻抗低通滤波器的理论基础
1．短传输线段的近似等效电路
阶梯阻抗低通滤波器是由特性阻抗很高或很低的短传输线段构成，短传输线段的近似等
Z、长度为l的传输线的Z矩阵为
效电路需要讨论。
一段特性阻抗为。
基于ADS的微带线阶梯阻抗低通滤波器设计
图 1 实际低通滤波器原型
采用电容输入式梯形网络，图 1 中各元件的cZc C3＝g3/2πfcZc L2＝L4＝g2Zc/2π fc
（2） （3） （4）
在计算滤波器的结构尺寸过程中，一般对选用的高低阻
抗传输线有如下要求：
Z oh
³
gLZC p /4
Z oL
£
pZC 4 gc
（5） （6）
Zoh 是当选取高阻抗线作为传输线时，计算得出的高阻抗
线的特性阻抗，ZoL 是计算得出的低阻抗线的特性阻抗。实际
等效于一串联电感，低阻抗线近似等效于一并联电容，把相应的高阻抗线和低阻抗线相互级联起来，这就构成了微带低通滤
波器，其具有结构简单，容易加工等优点。文章进行了理论计算，并用 ADS 进行了优化仿真，仿真结果显示其具有良好的
频带响应特性。
【关键词】滤波器设计；阶梯阻抗滤波器；ADS 软件；频带响应
【中图分类号】TN713
Key words: filter design; step-impedance microstrip line; ADS software; frequency response
1 介绍
滤波器在通信/雷达系统中发挥着重要的作用[1]，随着信 息技术的发展，人类对通信系统的要求也越来越高，随之而 来的是信号频域的更加拥挤，各种频段的通信系统也相应出 现，这就出现了频段间的串扰问题，滤波器应运而生，并且 其性能很大程度上决定于传输信号的质量，直接影响到整个 系统性能好坏。微带滤波器具有设计灵活，质量轻，可以在 PCB 板上进行设计，便于集成化等诸多优点。尤其是在微波 频段，高选择性的滤波器被广泛应用，已经成为通信系统中 至关重要的电子器件。本文采用微带线高低阻抗线来设计一 种截止频率为 2GHz 的低通滤波器[2]，仿真结果显示其基本满 足设计要求。
基于ADS滤波器的设计
基于ADS滤波器的设计
宿玲玲;赛景波
【期刊名称】《电子器件》
【年(卷),期】2013(036)006
【摘要】介绍了基于ADS(Advanced Design System)软件进行微带线滤波器的设计方法,给出了详细的设计原理和步骤,并结合实例设计了一个中心频率为2.35 GHz,带宽为100 MHz,带内衰减小于2 dB,波纹起伏小于1 dB,输入阻抗、输出阻抗均为50 Ω的耦合微带线带通滤波器.经过仿真优化,得到了原理图和电路版图,证明了这种方法的可行性,对使用ADS设计滤波器具有一定指导作用.
【总页数】6页(P814-819)
【作者】宿玲玲;赛景波
【作者单位】北京工业大学电子信息与控制工程学院,北京100124;北京工业大学电子信息与控制工程学院,北京100124
【正文语种】中文
【中图分类】TN713
【相关文献】
1.基于ADS的声表滤波器匹配电路设计方法 [J], 简义全
2.一种基于ADS的发夹型带通滤波器设计 [J], 罗时书;朱彩霞;潘汉坏
3.基于ADS的KBNN在带通滤波器优化设计中的应用 [J], 陈艺;车久菊;田雨波
4.基于ADS的微带线阶梯阻抗低通滤波器设计 [J], 仇亮
5.基于ADS的小型化切比雪夫带通滤波器的设计 [J], 余晖冬;阮维剑;侯柳英
因版权原因，仅展示原文概要，查看原文内容请购买。
课程设计——基于ADS的微带滤波器设计
课程设计报告题目：基于ADS的微带滤波器设计姓名：学号：班级：电子101专业：电子信息工程指导老师：提交时间： 2014-01-051.绪论我们利用微波滤波器只让频率正确的的信号通过阻碍频率不同的信号的特性来区分信号。
滤波器的性能对微波电路系统的性能指标有很大的影响，因此设计微波电路系统时设计出具有高性能的滤波器很重要。
微带电路在微波电路系统应用广泛路。
具有个体，质量轻、频带分布宽等特点，其中用微带做滤波器是其主要应用之一，微带滤波器当中最基本的滤波器是微带低通滤波器，而别的滤波器可以通过低通滤波器为原型转化过来。
其中最大平坦滤波器和切比雪夫滤波器是两种常用的低通滤波器的原型。
因此本节将重点研究如何设计并优化微带滤波器1.1 微带滤波器简介滤波器是一个的二端口网络，对频率适合的信号进行传输，对频率不匹配的信号进行发射衰减，从而实现信号频谱过滤。
典型的频率响应包括低通、高通、带通、带阻衰减。
如图1-1所示.还可以从不同角度对滤波器进行分类：(1)按功能分，低通滤波器，高通滤波器，带通滤波器，带阻滤波器，可调滤波器。
(2)按用的元件分，集总参数滤波器，分布参数滤波器，无源滤波器，有源滤波器，晶体滤波器，声表面波滤波器，等。
1.2微带滤波器的主要参数（1）中心频率：一般取f0=（f1+f2）/2，f1、f2为带通或带阻滤波器左、右相对下降1dB或3dB边频点。
窄带滤波器常以插损最小点为中心频率计算通带带宽。
（2）截止频率：指低通滤波器的通带右边频点及高通滤波器的通带左边频点。
通常以1dB或3dB相对损耗点来标准定义。
（3）通带带宽：指需要通过的频谱宽度，BWxdB=（f2-f1）。
f1、f2为以中心频率f0处插入损耗为基准，下降X（dB）处对应的左、右边频点。
通常用X=3、1、0.5 即BW3dB、BW1dB、BW0.5dB 表征滤波器通带带宽参数。
分数带宽=BW3dB/f0×100%，（4）纹波：指1dB或3dB带宽（截止频率）范围内，插损随频率在损耗均值曲线基础上波动的峰-峰值。
基于ADS的微带滤波器设计
Design of Low Phase-Noise Microwave Oscillator and Wideband VCO Based on MicrostripCombline Bandpass FiltersChao-Hsiung Tseng,Member,IEEE,and Chih-Lin ChangAbstract—This paper presents a new low phase-noise mi-crowave oscillator and wideband voltage-controlled oscillator (VCO)based on microstrip combline bandpassfilters.For this type of oscillator,the passbandfilter is embedded into the feed-back loop to treat as a frequency stabilization element.Instead of designing the oscillator at the group-delay-peak frequency of the filter to achieve a good phase-noise performance,in this paper, the peak frequency of the complex quality factor is adopted for oscillator design.To demonstrate the effectiveness of using -peak frequency,twofilter-based oscillators are implemented at the-peak and group-delay-peak frequencies,respectively. The oscillator designed at the-peak frequency improves the phase-noise about10dB as compared with that realized at the group-delay-peak frequency.The developed oscillator with the three-pole comblinefilter is experimentally demonstrated at2.05GHz with148.3-dBc/Hz phase noise at1-MHz offset frequency.Moreover,by attaching a varactor on each resonator of the comblinefilter,the oscillator can be extended to a wideband VCO.The developed VCO has a frequency tuning range from 1.3to2.2813GHz with a54.8%bandwidth.Over this frequency range,all the phase noises measured at1-MHz offset frequency are better than117.19dBc/Hz.Index Terms—Comblinefilter,filter-based oscillator,microwave oscillator,voltage-controlled oscillator(VCO).I.I NTRODUCTIONI N THE microwave regime,the oscillator is mainly em-ployed to produce a continuous wave(CW)signal.It can then be treated as a local-oscillating(LO)signal generator for performing the frequency up-conversion/down-conversion in a wireless communication system,or it can be applied to be a mi-crowave source in a radar system.As the oscillation frequency of an oscillator can be properly tuned by embedded voltage-controlled devices,it can be also referred to as a voltage-con-trolled oscillator(VCO).The key performances of a VCO in-clude low phase noise,low power consumption,and wide fre-quency tuning range.Manuscript received June21,2012;revised July08,2012;accepted July17, 2012.This work was supported by the National Science Council of Taiwan under Grant NSC101-2221-E-011-080.The authors are with the Department of Electronic Engineering,National Taiwan University of Science and Technology,Taipei10607,Taiwan(e-mail: chtseng@.tw).Color versions of one or more of thefigures in this paper are available online at .Digital Object Identifier10.1109/TMTT.2012.2210441According to the Leeson’s phase-noise model[1],the spec-trum-based quality factor dominates the oscillation spec-trum.To achieve a good phase-noise performance,the overall network of the oscillator should have a high value at the os-cillation frequency.Hence,a resonator with a high quality factor is usually employed to increase.Here,the quality factor of the resonator is defined as(1) where is the oscillation frequency,is the phase re-sponse of the resonator,and is the group delay.Note that the spectrum-based quality factor[2],[3]is different from the quality factor of the resonator.In practical applications, the high-resonators,such as the dielectric resonator(DR) [4]and metallic air cavity[5],are usually adopted to develop low phase-noise oscillators.However,they are not easy to in-tegrate with other planar circuits,and they are impossible to be implemented in the integrated circuit(IC)process.Besides,the mechanical tuning technique should be adopted to realize the frequency tuning function of the DR or cavity oscillator.To overcome the above-mentioned problems,recently,a new type of the planar microwave oscillator[6],[7]has been pro-posed to achieve a good phase-noise performance.Instead of using only one high-resonator,it utilizes a four-pole el-liptic-responsefilter as a frequency-selective element to develop a loop oscillator.It is because the multipole bandpassfilter can synthesize two group-delay peaks near two corner frequencies of the passband.According to(1),these two group-delay peaks are corresponding to two high values,respectively.There-fore,as the oscillation frequency is designed at the group-delay-peak frequency,the phase-noise performance can be dramati-cally improved.However,for some types of microwavefilters, the frequencies of the peak values are not absolutely mapped to those of the high values.If the oscillator is still designed at the group-delay-peak frequency,it may not achieve the best phase-noise performance.Besides,the low phase-noise oscil-lator proposed in[6]and[7]is difficult to be extended to the VCO with a moderate frequency tuning range.Although the multiple split-ring resonatorfilter[8]and trisectionfilter[9] have been employed to develop VCOs,their frequency tuning ranges are very limited.To further reduce the phase noise,the passive four-polefilter in[6]and[7]is extended to become an activefilter and embedded into the feedback loop of the oscillator[10].However,it increases the manufacturing cost,0018-9480/$31.00©2012IEEEFig.1.Block diagram of a feedback oscillator.namely,adding two microwave transistors,to achieve a better performance.Instead of using the group-delay peak and the phase-noise figure-of-merit(PNFOM)[7]to evaluate thefilter characteris-tics for the oscillator design,in this paper,the complex quality factor[2],[3]is introduced to simultaneously consider ef-fects of the amplitude and phase responses of thefilters,and then applied to implement low phase-noise oscillators using the two-pole coupled-resonator and three-pole comblinefilters[11]. Since the is inherently related to the spectrum-based quality factor of the Leeson’s model[1],the phase-noise perfor-mance of the oscillator can be significantly improved as de-signed at the frequency of the peak.In addition,by attaching varactors to the resonators of the comblinefilter[12],[13],one can easily extend the developed oscillator to a wideband low phase-noise VCO with a54.8%frequency tuning range.II.O SCILLATOR D ESIGN U SING Q UALITY F ACTORplex Quality FactorReferring to the Leeson’s oscillator model[1],the output os-cillation spectrum can be expressed as(2) where is the offset frequency from the oscillation frequency ,is the additive noise component,and the is the spectrum-based quality factor,which dominates the oscillation spectrum.Fig.1shows afilter-based loop oscillator with a cur-rent-controlled current source(CCCS)active device,namely, the BJT amplifier.The characteristics of the bandpassfilter are represented by two-port impedance parameters.Assuming that the effects of the output load,connecting lines,and para-sitic components are ignored,the complex quality factor is defined as[2](3) It can be related to the spectrum-based quality factor as[3].Moreover,translating into the polar coordinate, it can be presented as[3](4)Fig.2.(a)Four-pole coupled-resonatorfilter and(b)its complex quality factor and group delay.Observing(4),one can learn that the not only considers the derivative of the phase response,,with respect to the frequency,but also the amplitude effects of thefilter.It is more rigorous than the quality factor defined in(1).Forfilter-based oscillator design in[7],the oscillation frequency is desig-nated at the group-delay peak of thefilter,namely,only consid-ering the derivative of the transmission phase angle,,of thefilter.In[7],the amplitude effects influenced by the band-width,location of transmission zero,and return loss of thefilter are evaluated by a newly defined factor,i.e.,the PNFOM.Actu-ally,the amplitude effects discussed in[7]has been including in (4).Section II-B will use complex quality factor to evaluate the two-and four-pole coupled-resonatorfilters.plex Quality Factor of FilterIn[6]and[7],the four-pole coupled-resonatorfilter is em-ployed to design a low phase-noise oscillator.To comprehen-sively understand the characteristics of thisfilter,as shown in Fig.2(a),a four-pole elliptic-response bandpassfilter is imple-mented on an RO4003substrate with a thickness of0.508mm, a dielectric constant of3.38,and a loss tangent of0.0027.The center frequency and fractional bandwidth of thefilter are set to2GHz and4%,respectively.The normalized frequency of the attenuations pole is selected to.Hence,the element values of the low-pass prototypefilter[11]are, ,,,and.TSENG AND CHANG:DESIGN OF LOW PHASE-NOISE MICROWA VE OSCILLATOR AND WIDEBAND VCO3The coupling coefficients and external quality factor[11]are calculated as,, ,and.The electromagnetic(EM)simulator Agilent Momentum is used to determine the physical dimen-sions as shown in Fig.2(a).Transferring the simulated-pa-rameters of thefilter to-parameters,the complex quality factor are calculated by(3),while the group delay is obtained by performing the derivative of the phase response.The cal-culated and group delay are plotted in Fig.2(b).For this four-polefilter,the frequencies of two group-delay peaks are almost the same as those of the peak.Consequently,the os-cillators designed at the high-frequency[6]and low-frequency [7]group-delay peaks can achieve a significant improvement of the phase-noise performance.In addition,since thefilter at the design center frequency has a lower insertion loss and a mod-erate group delay value,it forms a peak at about2GHz. Note that since the modulus is performed in(3),the transmis-sion zeros of thefilter will contribute two pseudo peaks indicated in Fig.2(b),which are also corresponding to negative notch points of the group-delay curve.As shown in Fig.3(a),a two-pole coupled-resonatorfilter with the Butterworth response is designed at2GHz with a3% fractional bandwidth.The element values of the low-pass pro-totypefilter[11]are,,, and,and their corresponding coupling coefficients and external quality factor are calculated as and .The simulated phase response of the developed filter is given in Fig.3(b).It has an abrupt slope at the de-sign frequency of thefilter,about2GHz.Observing the group delay and complex quality factor given in Fig.3(c),two group-delay peaks are located near the corner frequencies of the filter.However,as compared with Fig.2(b),only a peak ap-pears at the center frequency of the passband because the slope of the phase response curve is not sharp enough to form two peaks close to two group-delay peaks.According to design procedures in[6]and[7],the oscillator is suggested to be de-signed at the frequency of group-delay peak.However,based on (2),the oscillator should be implemented at the frequency of thepeak.To judge which peak frequency shown in Fig.3(c)is better for the low phase-noise oscillator design,in Sections II-C and II-D,two oscillators will be designed at the-peak and group-delay-peak frequencies.C.Oscillator Designed at-Peak FrequencyBased on the block diagram shown in Fig.1,afilter-based loop oscillator can be realized by an amplifier with a bandpass filter embedded in the feedback path.Here,thefilter is replaced by the two-pole coupled-resonatorfilter shown in Fig.3(a).The amplifier is realized by an Infineon BFP405bipolar transistor, which is biased at V with a collector current mA,as shown in the inset of Fig.1.To completely con-sider effects of the parasitic components and bias circuitry,the phase response of the amplifier arefirst measured as shown in Fig.4(a)for the oscillator design.By integrating thefilter,am-plifier,parts of the connecting lines,and50-load in the circuit simulator,the total phase response can be achieved as shown in Fig.4(b).According to the“Barkhausen oscillation criteria,”the loop gain of the oscillator must be greater than unity and thetotal Fig.3.(a)Two-pole coupled-resonatorfilter and(b)its phase response, (c)complex quality factor,and group delay.loop phase should satisfy0or multiple of360.Thus,to de-sign the oscillator operated at the-peak frequency,namely, 2.01GHz,the length of the transmission line to connect ports1 and2in Fig.4(b)can be determined as360220.78.The physical dimensions of the connecting line are clearly indicated in Fig.5(a).Fig.5(a)and(b)shows the circuit photograph of the devel-oped oscillator,and simulated loop gain and phase,respectively. As shown in Fig.5(c),the output spectrum is measured by Agi-lent Spectrum Analyzer N9010A with the settings of a100-kHz resolution bandwidth and a10-MHz frequency span.The output power is2.4dBm at the oscillation frequency1.986GHz,which is close to the frequency with a0loop phase,as shown in Fig.5(b).The amount of the consumed dc power is20mW. The phase noise of the developed oscillator is measured by Ag-ilent source signal analyzer E5052B.As shown in Fig.6,the4IEEE TRANSACTIONS ON MICROWA VE THEORY ANDTECHNIQUESFig.4.(a)Measured phase response of the amplifier.(b)Total phase response of the amplifiter with thefilter,parts of connecting lines and50-load. measured phase noises are117dBc/Hz and140dBc/Hz at 100-kHz and1-MHz offset frequencies,respectively.Thefigure of merit(FOM)[14]of an oscillator can be calculated bymW(5) where is the phase noise at the offsetfrequency,is the oscillation frequency,and is the dc power consumption Fig.5.(a)Circuit photograph of the oscillator designed at the-peak fre-quency and(b)its simulated loop gain and loop phase and(c)measured output spectrum.(in milliwatts).The FOM of the developed oscillator at1-MHz offset frequency is192.9dBc/Hz.D.Oscillator Designed at Group-Delay-Peak Frequency Following the design procedures described in Section II-C, the oscillator operated at the group-delay-peak frequency,TSENG AND CHANG:DESIGN OF LOW PHASE-NOISE MICROWA VE OSCILLATOR AND WIDEBAND VCO5Fig.6.Measured phase noises of the oscillator designed at the-peak and group-delay-peak frequencies.namely,1.98GHz,is developed as shown in Fig.7(a).Except for the length of the connecting line,the oscillator shown in Fig.7(a)is the same as that of Fig.5(a).Since the phase response of thefilter shown in Fig.3(b)has a abrupt curve slope around the design frequency,a longer folded microstrip should be adopted to satisfy the loop phase requirement as compared with the oscillator in Fig.5(a).Shown in Fig.7(b)are the simu-lated loop gain and phase of the developed oscillator.Referred to the measured output spectrum shown in Fig.7(c),the output power is3.919dBm at the oscillation frequency1.9466GHz. As expected,the frequency with a0loop phase is close to the measured oscillation frequency,1.98GHz.The amount of the consumed dc power is20mW.As plotted in Fig.6,the measured phase noises are107dBc/Hz and130dBc/Hz at100-kHz and1-MHz offset frequencies,respectively.It reveals that designing the oscillator at the-peak frequency can achieve a10-dB phase-noise improvement as compared with the oscillator designed at the group-delay-peak frequency. However,since the oscillator designed at the group-delay-peak frequency has a higher loop gain,it can provide a higher output power as expected.It is worth noting that the-peak and group-delay-peak fre-quencies of the four-pole coupled-resonatorfilter in Fig.2(a) are almost located at the same frequency,as well as the conven-tional LC tank resonator.Therefore,whether the oscillator is designed at the-peak or group-delay-peak frequency,one will obtain a similar phase noise level.However,as the peak and group-delay peak of thefilter are located at different frequencies,such as those of the two-pole coupled resonator filter,as shown in Fig.3(c),the oscillator should be designed at the-peak frequency to achieve a better phase-noise per-formance.It also demonstrates that the complex quality factor is more rigorous parameter than the group delay for evalu-ating thefilter.E.Design Procedures of Filter-Based OscillatorThe design procedures of thefilter-based oscillator proposed in this paper are summarized asfollows.Fig.7.(a)Circuit photograph of the oscillator designed at the group-delay-peak frequency and(b)its simulated loop gain and loop phase and(c)measured output spectrum.1)Design and simulate thefilter by the EM simulator andthen apply the de-embedded technique to acquire the phase response,as shown in Fig.3(b).6IEEE TRANSACTIONS ON MICROWA VE THEORY AND TECHNIQUES2)Use(3)to calculate of thefilter,as illustrated asFig.3(c),and then designate the oscillation frequency of the oscillator to be the-peak frequency.3)Design the amplifier to have a proper gain,and then mea-sure the phase response,as shown in Fig.4(a),with the thru-reflect-line(TRL)calibration to remove the effects of the testfixture.4)Integrate the-parameters of thefilter and amplifier[ob-tained in1)and3)]with the50-load and connecting lines in the circuit simulator,as plotted in Fig.4(b),and predict the total phase angle.5)Design the transmission line with the electrical length ofat the oscillation frequency.III.O SCILLATOR D ESIGN B ASED ON C OMBLINE F ILTERIn[6]and[7],thefilter-based oscillators have been success-fully developed with very low phase-noise performances.How-ever,they are only operated at a single frequency and are unsuit-able for applying in the wireless communication or radar system with the frequency tuning requirement.Since the comblinefilter has the advantage of the simple circuit structure and easy exten-sion to a tunablefilter[12],[13],it will be employed to imple-ment the oscillator and VCO in this paper.In Sections III-A–C, the oscillator based on the comblinefilter will befirst designed and then extended to a wideband VCO.A.Oscillator Design Using Combline FilterAs shown in Fig.8(a),the three-pole combline bandpassfilter developed in this paper is composed of three coupled quarter-wave resonators.The open-and short-circuited terminations are connected with the bilateral ends of each resonator.Moreover, thefilter is directly fed by two tapped lines.Thefilter is de-signed with the Chebyshev response at2GHz and fabricated on the RO4003substrate.Since the fractional bandwidth of the filter is set to4%,the element values of the low-pass prototype filter[11]are,,,, and.The coupling coefficients and external quality factor are calculated as,and .Based on the above parameters,the physical dimensions of thefilter are determined by the EM simulator and also indi-cated in Fig.8(a).Shown in Fig.8(b)are the measured insertion loss and group-delay response of thisfilter.Although the group delay peak at about2.05GHz has a higher value,it is corre-sponding to a worse insertion loss.If the designer determines the quality factor only by the group delay,namely,by using(1), the group-delay peak at about2.05GHz will reasonably cor-respond to a higher quality factor.However,as simultaneously considering the effects of the insertion loss and group delay,two peak values of illustrated in Fig.8(c)are almost equal.In addition,two peaks are close to group-delay peaks,but not exactly located at the same frequencies.In[7],the amplitude ef-fects of thefilter are considered by performing the PNFOM pa-rameter study.In this paper,the more rigorous complex quality factor is adopted to evaluate thefilter performance,and the frequency with the peak will then be chosen to design a low phase-noise oscillator.Followed by the oscillator design procedures in Section II-E, the comblinefilter shown in Fig.8(a)is employed to designthe Fig.8.(a)Three-pole comblinefilter and(b)its measured insertion lossand group delay and(c)complex quality factor calculated from measured -parameters of the comblinefilter.oscillator operated at the-peak frequency,2.0493GHz,as shown in Fig.9(a).Basically,the circuit configuration is sim-ilar to the oscillators developed in Section II,except for re-placing thefilter structure and adding the tuning inductors.The microstrip lines are adopted to connect thefilter and the ampli-fier,and their dimensions are indicated in Fig.9(a).Here,the shunt tuning inductors are mainly used tofine tune the loop phase for satisfying the oscillation criteria.Their function is similar to the network embedded in feedback loop in[6]and [7].Since this oscillator will be extended to a wideband VCO, in this design,there are no narrowband matching networks at-tached with the transistor.As shown in Fig.9(b),the measured output power is0.685dBm at the oscillation frequency ofTSENG AND CHANG:DESIGN OF LOW PHASE-NOISE MICROWA VE OSCILLATOR AND WIDEBAND VCO7Fig.9.(a)Circuit photograph of the oscillator using the comblinefilter and(b)its measured output spectrum.2.0472GHz.Referred to the wideband output spectrum illus-trated in Fig.10,this oscillator has an18.82-dBc second har-monic and18.18-dBc third harmonic suppressions.The mea-sured phase noise is shown in Fig.11,and two asymptotes with the slopes of30and20dB/decade are also plotted to reveal the trend of the phase-noise curve.The measured phase noises are125.6and148.3dBc/Hz at100-kHz and1-MHz offset frequencies,respectively.The dc power consumption of the de-veloped oscillator is22mW.By using(5),the FOM at1-MHz offset frequency is201.1dBc/Hz.Fig.10.Measured wideband output spectrum of the developed oscillator using the comblinefilter.Fig.11.Measured phase noises of the developed oscillator using the combline filter.plex Quality Factor of OscillatorIn Section II-B,the complex quality factor is used to evaluate thefilter,and then choose the-peak frequency for the low phase-noise oscillator design.In order tofigure out the reason why the phase-noise performance of the developed os-cillator using a comblinefilter can be significantly improved, in this section,will be employed to quantitatively evaluate the oscillator.Based on the method in[2],the developed oscil-lator using the comblinefilter shown in Fig.9(a)can be rep-resented as Fig.12(a)with the equivalent circuit model of the bipolar junction transistor(BJT).The component values of the BJT(Infineon BFP405)circuit model are given in Table I.Here, the two-port impedance network represents the characteris-tics of the comblinefilter,conneting lines,bias network,and output load of the oscillator.Embedding the parasitic compo-nents of the BJT to the network,one can obtain the equiva-lent circuit shown in Fig.12(b),which is mainly composed of the intrinsic part of the BJT and the parasitic-embedded net-work.By applying(3),the complex quality factor of the oscillator can be calculated from-parameters,as shown in Fig.13.Since the oscillator is designed at the peak of the filter,namely,2.0493GHz,the peak of the oscillator around this frequency is conserved well.The other peak of thefilter at1.9708GHz is obviously degraded.Referring to Fig.13,the8IEEE TRANSACTIONS ON MICROWA VE THEORY ANDTECHNIQUESFig.12.(a)Developed oscillator represented with the BJT equivalent model and (b)its equivalent circuit with parasitic components embedding from the BJT to the filter network.TABLE IC OMPONENT V ALUES OF BJT E QUIVALENT C IRCUIT MODELpeak appears at 2.0515GHz,which is very close to the measured oscillation frequency,2.0472GHz,of the developed oscillator.Hence,one can achieve a very good phase-noise per-formance.C.VCO Design Using Tunable Combline FilterBased on the design procedures in [13],the combline filter shown in Fig.8(a)can be extended to a tunable combline filter,as depicted in Fig.14(a).The varactor (Skyworks SMV 1233)is attached on the open-circuited end of the resonator for providing a capacitance tuning range of 0.84–3.28pF.The bias circuit of the varactor is also clearly shown in Fig.14(a).The center frequency of the tunable filter is set to 2GHz and the electrical length of the resonator is 37.5.The resonator becomes shorter because the parasitic capacitance of the varactor providessomeFig.13.Calculated complex quality factor of the developed oscillatorusing the combline filter.Fig.14.(a)Developed tunable combline filter and (b)its complex quality fac-tors calculated from measured -parameters for different tuning voltages.equivalent length.Plotted in Fig.14(b)are the peak values of the tunable combline filter for the different tuning voltages .They are calculated from measured -parameters by the procedures in Section II.For a decreasing tuning voltage,thepeak goes to the lower frequency band with a lower value.It implies that as one uses this tunable filter to develop a VCO,the phase-noise performance will be degraded by tuning the oscillation frequency to the lower frequency band.TSENG AND CHANG:DESIGN OF LOW PHASE-NOISE MICROWA VE OSCILLATOR AND WIDEBAND VCO9Fig.15.Circuit photograph of the wideband VCO using the tunable combline filter.Fig.16.(a)Measured phase noises,oscillation frequencies and (b)output power of the developed wideband VCO.Replacing the combline filter in Fig.9(a)by the developed tunable filter,one can form a VCO,shown in Fig.15.Here,theTABLE IIP ERFORMANCE C OMPARISONS B ETWEEN P UBLISHED VCOs AND T HIS STUDYlength of the connecting line is adjusted to obtain an optimal frequency tuning range.As shown in Fig.16(a),the available frequency tuning range of the developed VCO is from 1.3to 2.2813GHz with a 54.8%bandwidth.Over this tuning range,all the measured phase noises at the 100-kHz and 1-MHz offset fre-quencies are better than 93and 117.19dBc/Hz,respectively.The best phase noises at the 100-kHz and 1-MHz offset frequen-cies can be achieved at 2.2813GHz,and they are 109.87and 134.17dBc/Hz,respectively.Here,the measured phase noises become better as the oscillation frequency is tuned to the higher frequency band.The phase-noise curve is opposite to the curve tread of the peak values of the tunable combline filter,as il-lustrated in Fig.14(b).The output powers are varied from 4.7to 2.38dBm,as shown in Fig.16(b).Since the measured power gain of the ampli fier decreases about 2.5dB over the frequency tuning range,as given in Fig.16(b),it leads to a notable variation of the VCO output power.The FOM at 1-MHz offset frequency is 188.3dBc/Hz.As compared with the developed oscillator in Section III-B,the phase-noise performance of the VCO has some degradation due to the parasitic element losses of the var-actors.The performance comparisons between published VCOs and this study are summarized in Table II.Although the VCO in [8]has a better FOM than that developed in this paper,it oc-cupies a large circuit area and only provides a 1.6%frequency tuning range.IV .C ONCLUSIONIn this paper,the complex quality factor is introduced to evaluate the filter performance,and then employed to designate the -peak frequency for the low phase-noise oscillator design.Section II experimentally demonstrates that as the -peak frequency of the filter is different from the group-delay-peak frequency,one should design the oscillator at the -peak frequency to achieve a better phase-noise performance.Since the value simultaneously considers the amplitude and phase effects of the filter,it is more rigorous than the group-delay evaluation approach [7],and able to replace the PNFOM parameter study in [7].Based on the proposed oscillator design procedures,the oscillator using the three-pole microstrip combline filter is developed at 2.05GHz with a measured 148.3-dBc/Hz phase noise at 1-MHz offset fre-quency.In addition,the value of the developed oscillator is calculated to quantitatively figure out the reason of achieving this very low phase noise.By attaching a varactor on each resonator of the combline filter,the developed oscillator can be10IEEE TRANSACTIONS ON MICROWA VE THEORY AND TECHNIQUESeasily extended to a wideband VCO with a54.8%frequency tuning range.In the future,the proposed circuit schematics of the VCO may be implemented in the IC process to achieve a low phase-noise monolithic microwave integrated circuit (MMIC)VCO.R EFERENCES[1]D.B.Leeson,“A simple model of feedback oscillator noise spectrum,”Proc.IEEE,vol.54,no.2,pp.329–330,Feb.1966.[2]T.Ohira,“Rigorous-factor formulation for one-and two-portpassive linear networks from an oscillator noise spectrum viewpoint,”IEEE Trans.Circuits Syst.II,Exp.Briefs,vol.52,no.12,pp.846–850,Dec.2005.[3]T.Ohira and K.Araki,“Oscillator frequency spectrum as viewed fromresonant energy storage and complex factor,”IEICE Electron.Exp.,vol.3,no.16,pp.385–389,Aug.2006.[4]n,D.Kalokitis,E.Mykietyn,E.Hoffman,and F.Sechi,“Highlystabilized ultra-low noise FET oscillator with dielectric resonator,”inIEEE MTT-S Int.Microw.Symp.Dig.,1986,pp.83–86.[5]G.D.Vendelin,A.M.Pavio,and U.L.Rohde,Microwave CircuitDesign Using Linear and Nonlinear Techniques.New York:Wiley,1990,ch.6.[6]J.Choi,M.-H.Chen,and A.Mortazawi,“An-band low phasenoise oscillator employing a four-pole elliptic-response microstripbandpassfilter,”in IEEE MTT-S Int.Microw.Symp.Dig.,Jun.2007,pp.1529–1532.[7]J.Choi,M.Nick,and A.Mortazawi,“Low phase-noise planar oscil-lators employing elliptic-response bandpassfilters,”IEEE Trans.Mi-crow.Theory Tech.,vol.57,no.8,pp.1959–1965,Aug.2009.[8]J.Choi and C.Seo,“Microstrip square open-loop multiple split-ringresonator for low-phase-noise VCO,”IEEE Trans.Microw.TheoryTech.,vol.56,no.12,pp.3245–3252,Dec.2008.[9]C.-L.Chang and C.-H.Tseng,“Design of low phase-noise oscillatorand voltage-controlled oscillator using microstrip trisection bandpassfilter,”IEEE Microw.Wireless Compon.Lett.,vol.21,no.11,pp.622–624,Nov.2011.[10]M.Nick and A.Mortazawi,“Low phase-noise planar oscillators basedon low-noise active resonators,”IEEE Trans.Microw.Theory Tech.,vol.58,no.5,pp.1133–1139,May2010.[11]J.-S.Hong and ncaster,Microstrip Filter for RF/MicrowaveApplication.New York:Wiley,2001.[12]I.C.Hunter and J.D.Rhodes,“Electronically tunable microwave band-passfilters,”IEEE Trans.Microw.Theory Tech.,vol.MTT-30,no.9,pp.1354–1360,Sep.1982.[13]G.Torregrosa-Penalva,G.López-Risueno,and J.I.Alonso,“A simplemethod to design wideband electronically tunable comblinefilters,”IEEE Trans.Microw.Theory Tech.,vol.50,no.1,pp.172–177,Jan.2002.[14]M.Tiebout,“Low-power low-phase-noise differentially tuned quadra-ture VCO design in standard CMOS,”IEEE J.Solid-State Circuits,vol.36,no.7,pp.1018–1024,Jul.2001.[15]C.M.Yuen and K.F.Tsang,“A1.8-V distributed voltage-controlledoscillator module for5.8-GHz ISM band,”IEEE Microw.WirelessCompon.Lett.,vol.14,no.11,pp.525–527,Nov.2004.[16]G.Avitabile,F.Cannone,M.Capodiferro,L.Carella,and N.Lofù,“Coarse-fine,wideband distributed voltage controlled oscillator forwireless applications,”Electron.Lett.,vol.42,no.5,pp.285–286,Mar.2006.[17]J.Choi and C.Seo,“Broadband and low phase noise VCO using tun-able metamaterial transmission line based on varator-loadedsplit-ring resonator,”in Proc.Korea–Japn.Microw.Conf.,2007,pp.145–148.Chao-Hsiung Tseng(S’03–M’05)was born inMiaoli,Taiwan,in1974.He graduated in electronicengineering from the National Taipei Institute ofTechnology,Taipei,Taiwan,in1994.He receivedthe M.S.and Ph.D.degrees in communication en-gineering from National Taiwan University,Taipei,Taiwan,in1999and2004,respectively.From November1999to August2000,he was anAssociate Microwave Researcher with the Center forMeasurement Standards,Industrial Technology Re-search Institute,Hsinchu,Taiwan.From August2001 to July2002,he was a Teaching Assistant with the Department of Electrical Engineering,National Taiwan University,where from February2004to July 2005,he was a Postdoctoral Research Fellow.From August2005to July2006, he was with the Department of Electrical Engineering,University of California at Los Angeles(UCLA),as a Visiting Scholar.Since August2006,he has been on the faculty of the Department of Electronic Engineering,National Taiwan University of Science and Technology,Taipei,Taiwan,where he is currently an Associate Professor.His research interests include microwave circuits and modules,microwave and millimeter-wave ICs,left-handedmetamaterials,mi-crowave measurement and calibration techniques,microwave-imaging systems, and techniques.Chih-Lin Chang was born in Chiayi,Taiwan,in1983.He received the B.S.degree in electrical engi-neering from Da-Yeh University,Changhua,Taiwan,in2006,the M.S.degree in electronic engineeringfrom National Taiwan University of Science andTechnology,Taipei,Taiwan,in2008,and is currentlyworking toward the Ph.D.degree at the NationalTaiwan University of Science and Technology.His research interests include microwave/mil-limeter-wave ICs,left-handed metamaterials,andmicrowave active and passive circuits.。
基于ADS的微带线带通滤波器设计
项目名称：基于ADS优化的微带带通滤波器设计一、实验目的(1) 了解低通滤波器、带通滤波器、高通滤波器等滤波器原理(2) 利用ADS2008 软件设计，以切比雪夫滤波器为原型，设计一种微带线带通滤波器。
二、实验设备(1) PC 机一台；(2) ADS2008 软件；三、实验内容和要求(1) 设计一个微带线带通滤波器，以切比雪夫低通滤波器为原型；(2) 中心频率：2G+学号*50MHz ；（2G+10*50MHz=2.5GHz ）(3) 相对带宽：8％；（2.5GHz*8 ％=200MHz ）四、实验原理1. 滤波器原理滤波器的基础是谐振电路,它是一个二端口网络,对通带内频率信号呈现匹配传输,对阻带频率信号失配而进行发射衰减,从而实现信号频谱过滤功能。
典型的频率响应包括低通、高通、带通和带阻特性。
镜像参量法和插入损耗法是设计集总元件滤波器常用的方法。
对于微波应用,这种设计通常必须变更到由传输线段组成的分布元件。
Richard 变换和Kuroda 恒等关系提供了这个手段。
2. 微带线微带线(microstrip1ine) 是现在混合微波集成电路和单片微波集成电路使用最频繁的一种平面传输线。
它可用光科程序制作,且容易与其他无源微波电路和有源微波器件集成,从而实现微波部件和系统的集成化。
微带线是在金属化厚度为h 的介质基片的一面制作宽度为W ，厚度为t 的导体带,另一面作接地金属平板而构成的。
3. 耦合微带线当两个无屏蔽的传输线紧靠一起时,由于传输线之间电磁场的相互作用,在传输线之间会有功率耦合,这种传输线称为耦合传输线。
耦合微带传输线由靠得很近的 3 个导体构成。
这种结构介质厚度为d,介质相对介电常数为η,,在介质的下面为公共导体接地板,在介质的上面为 2 个宽度为W、相距为S 的中心导体带。
五、实验步骤与结果1. 设定滤波器指标中心频率： 2.5GHz通带带宽：200MHz （2.4~2.6GHz ）输入输出的阻抗：50Ω插入损耗：小于2dB阻带衰减：在距离中心频率300MHz 处的衰减大于50dB相对带宽：8％（表示信号带宽为0.2GHz）带内输入输出端口反射系数：小于-15dB4. 滤波器选用与微带线的计算2.dB 切比雪夫滤波器， 5 阶。
ADS仿真-微带滤波器的设计
ADS仿真：微带滤波器的设计关键字：ADS 仿真滤波器微波滤波器是用来分离不同频率微波信号的一种器件。
它的主要作用是抑制不需要的信号, 使其不能通过滤波器, 只让需要的信号通过。
在微波电路系统中，滤波器的性能对电路的性能指标有很大的影响，因此如何设计出一个具有高性能的滤波器，对设计微波电路系统具有很重要的意义。
微带电路具有体积小，重量轻、频带宽等诸多优点，近年来在微波电路系统应用广泛，其中用微带做滤波器是其主要应用之一，因此本节将重点研究如何设计并优化微带滤波器。
1 微带滤波器的原理微带滤波器当中最基本的滤波器是微带低通滤波器，而其它类型的滤波器可以通过低通滤波器的原型转化过来。
最大平坦滤波器和切比雪夫滤波器是两种常用的低通滤波器的原型。
微带滤波器中最简单的滤波器就是用开路并联短截线或是短路串联短截线来代替集总元器件的电容或是电感来实现滤波的功能。
这类滤波器的带宽较窄，虽然不能满足所有的应用场合，但是由于它设计简单，因此在某些地方还是值得应用的。
2 滤波器的分类最普通的滤波器的分类方法通常可分为低通、高通、带通及带阻四种类型。
图12.1给出了这四种滤波器的特性曲线。
按滤波器的频率响应来划分，常见的有巴特沃斯型、切比雪夫Ⅰ型、切比雪夫Ⅱ型及椭圆型等；按滤波器的构成元件来划分，则可分为有源型及无源型两类；按滤波器的制作方法和材料可分为波导滤波器、同轴线滤波器、带状线滤波器、微带滤波器。
3 微带滤波器的设计指标微带滤波器的设计指标主要包括：1绝对衰减（Absolute attenuation）：阻带中最大衰减（dB）。
2带宽（Bandwidth）：通带的3dB带宽（flow—fhigh）。
3中心频率：fc或f0。
4截止频率。
下降沿3dB点频率。
5每倍频程衰减（dB/Octave）：离开截止频率一个倍频程衰减（dB）。
6微分时延（differential delay）：两特定频率点群时延之差以ns计。
7群时延（Group delay）：任何离散信号经过滤波器的时延（ns）。
利用ADS中的滤波器向导工具设计微带线滤波器
D esign of M icrostr ip F ilter Ba sed on D esign 2gu ide of Software AD S Zhou Zheng1, 2 , Song Yu2fei1 ( 1. College of Comm un ica tion Eng ineering, N an jing Institu te of Technology, N an jing J iangsu 211167, Ch ina; 2. College of Inform a tion S cience and Eng ineering, S ou theast U n iversity, N an jing J iangsu 210096, Ch ina) Abstract: This paper introduces a method for designing m icrostrip filter based on design2guide of software ADS; p resents the de2 sign app roach and examp le, and it also verifies the feasibility of methodology by simulation results. Key words:m icrostrip; filter; ADS; design2guide
近年来 ,随着射频电路辅助设计软件的不断发展 ,利用 仿真软件进行微带线滤波器的设计 ,可以绕开复杂的理论计 算和推导 。ADS是安捷伦公司设计开发的一款 EDA 软件 , 它可以模拟整个信号通路 ,完成包括从原理图到板图 、系统 的各级仿真 ,当任何一级仿真结果不理想时 ,都可以回到原 理图中重新进行优化设计 、仿真 ,直到仿真结果满意为止 ,保 证了实际电路与仿真电路的一致性 。
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中 文 视 频 频 课 程
第 讲 ADS Filter DesignGuide快
高
线滤波
概 述
讲解和演示如何借助于ADS中的 Filter DesignGuide 功能快速设计出高低阻抗线微带滤波器
• Filter DesignGuide 确定满足设计要求的滤波器的阶数，设计出满足设计要求的集总LC滤波器
•
Passive Circuit DG - Microstrip Circuits > SIFilter (Stepped Impedance Lowpass Filter)，快速设计 出微带线结构的高低阻抗线滤波器
李明洋主讲，ADS高低阻抗线微带滤波器设计实例培训视频教程
Filter DesignGuide
李明洋主讲，ADS高低阻抗线微带滤波器设计实例培训视频教程
SIFilter SmartComponent
求解器
李明洋主讲，ADS高低阻抗线微带滤波器设计实例培训视频教程
设计实作
打开ADS软件，演示和讲解实际设计操作
实作 讲解
李明洋主讲，ADS高低阻抗线微带滤波器设计实例培训视频教程