百度作业网英语翻译317127782
来源：学生作业帮 编辑：百度作业网作业帮 分类：英语作业 时间：2024/06/17 22:28:51
英语翻译
317127782
317127782
从天线接收的微弱信号由处于射频接收机前端的放大器进行放大,因此要求该放大器具有一定的增益和较小的噪声系数.
本文借助Agilent公司的射频电路设计软件ADS(Advanced Design System)进行辅助设计一款高增益低噪声放大器(LNA),并对其进行了仿真验证.
1 射频放大器的组成
单级射频放大器的组成如图1所示,包括射频晶体管放大电路和输入、输出匹配网络三部分.
2 射频放大器的设计
2．1 晶体管的选择
选择好晶体管器件对低噪声放大器的设计至关重要.
根据工作频率、增益和噪声系数等指标要求,同时考虑到设计、仿真时便于得到相应的元器件模型,最终选用Avago公司的高电子迁移率晶体管(E-PHEMT)ATF-58143来进行设计(可以在Avago公司的网站上下载到ATF-58143的元件模型).
2．2 偏置电路的设计
设计LNA首先需要确定静态工作点,利用ADS中的“DC_FET_T”的模板可以很方便地仿真出其输出特性曲线.再参考ATF-58143的datash eet,可以确定当Vds=3 V,Ids=35 mA时,各项设计指标满足要求.
确定静态工作点后,就要确定偏置电路的形式和参数.不需人工计算,借助ADS中的设计向导工具(DesignGuide→Amplifier→Tools→ Transistor Bias Utility)可以轻易完成.因为ADS所提供的元件数值是非标称的,所以需要设计者用与ADS提供的数值接近的标称元件进行替代.偏置电路及各点静态参数如图2所示.
2．3 稳定性分析及改善
晶体管绝对稳定的条件是K>1,|△|<1.其中：
如果这两个条件不能同时得到满足,电路将存在潜在的不稳定和振荡的可能.对上述偏置条件下的晶体管进行稳定性仿真分析发现,在要求的工作频段内其稳定系数K<1,不满足绝对稳定的条件.
通过引入负反馈的方式可以改善电路的稳定性,同时也能够拓展工作带宽.在输出端和输入端之间串联RC电路引入负反馈,其中的R需要满足条件：
同时在两个源极加上小的电感引入负反馈进一步改善稳定性,该电感的值需反复调节后方能确定.
对引入负反馈后的电路再次仿真,其工作频带内稳定系数K>1,满足绝对稳定条件.
2．4 最小噪声系数的输入匹配电路设计,最大增益的输出匹配电路设计
如果输入匹配电路和输出匹配电路使射频器件的输入阻抗Zin和输出阻抗Zout都转换到标准系统阻抗Zo,即Zin=Zo,Zout=Zo(或,如图1所示)就可使器件的传输增益最高.但输入、输出匹配时,噪声并非最佳.当ΓS=Γopt时,可以得最小的噪声系数.
利用ADS可以很方便地绘制出等功率增益圆和等噪声系数圆,如图3所示.从图中可以看出,如果从m2点匹配到标准系统阻抗,将可以使电路获得最大的增益；如果从m3点匹配到标准系统阻抗,将可获得最小的噪声系数.显然最大增益和最小噪声系数不可同时得到.对于低噪声放大器,首要的是考虑最小噪声系数,因此对m3点进行匹配.借用ADS的自带工具“Smith Chart Utility Tool”进行,只要在其中设置好频率、源阻抗和目标阻抗值,就可以设计出所需要的输入匹配电路.
在输入端匹配完成以后,在原理图中加入阻抗测量控件测出输出阻抗,再次使用“Smith Chart Utility Tool”将输出阻抗匹配到标准系统阻抗,就可得到最大增益的输出匹配电路.
当输出端的匹配完成后,因为改变了从输入端向里看的等效阻抗Zin,输入端的回波损耗会变差.为此,可以采用优化控件对输入端和输出端的匹配电路进行同时的优化改进,也可以使用Tunig工具进行调节.
2．5 最终电路及仿真结果分析
匹配及优化后的电路如图4所示,电路中各元件的作用分别是：C6、L6是输入匹配电路；C7、L7是输出匹配电路；L1、L5、C3、R5是反馈元件；L3、L4是扼流电感；C4、C5是隔直耦合电容；C1、C2是旁路电容.
需要说明的是,反馈电感L1、L5和匹配电路中的元件C6、L6、C7、L7等因为数值较小,在工程中常用微带线来代替.
仿真结果如图5所示.其工作带宽达500 MHz,中心频率处增益接近20 dB,输入输出反射损耗小于-10 dB,噪声系数小于0．5 dB,稳定系数大于1.如果断开反馈电路后再次仿真,会发现增益有所加大,但稳定系数将小于1,放大电路将不能正常工作.
3 结论
通过射频低噪声放大器的设计与仿真,可以看到使用ADS辅助设计电路,理论计算简单,设计过程快速,参数修改容易,验证方便,缩短了设计周期,提高了设计精度,在工程中具有实用价值.
By a weak signal from the antenna in the rf receiver front-end amplifier amplification, therefore asked the amplifier gain and low noise factor.In this paper, with the aid of Agilent ADS of rf circuit Design software (Advanced Design System) for aided Design a high gain and low noise amplifier (LNA), and the simulation verification.1 the composition of the rf amplifierSingle stage composed of rf amplifier is shown in figure 1, including rf transistor amplifier circuit and the input and output matching network of three parts.2 the design of the rf amplifier2.1 the choice of the transistorGood selection transistor components for the design of the low noise amplifier is very important.According to the working frequency, gain and noise figure index requirements, at the same time when considering the design, the simulation is easy to get the corresponding components model, finally choose Avago company of high electron mobility transistor (PHEMT) E ATF - 58143 for design (can be downloaded on Avago company web site to the ATF components model - 58143).2.2 the design of the bias circuitDesigning LNA first need to determine the static working point, the use of ADS "DC_FET_T" templates can be easily in the simulation of the output characteristic curve. Reference ATF - 58143 again datash eet, can be determined when the Vds = 3 V, Ids = 35 mA, the design indexes meet the requirements.After determine the static working point, shall determine the form and the parameters of bias circuit. Do not need artificial calculation, with the aid of ADS in the design wizard tool (DesignGuide - Amplifier - > Tools - Transistor Bias, the Utility) can be done easily. Because the ADS provided by the component values are nominal, so designers need to use with the ADS provide alternative values close to the nominal elements. Bias circuit and some static parameters as shown in figure 2.2.3 stability analysis and improvementTransistor is K > 1, the absolute and stability of the | delta | < 1. Among them:If the two conditions cannot be satisfied at the same time, there will be potential instability and oscillatory circuit. Transistor of the bias conditions stability simulation analysis found that the stability coefficient within the required working frequency band K < 1, can not meet the needs of absolute stability conditions.By introducing feedback on ways to improve the stability of the circuit, but also can extend working bandwidth. Between the output and the input series RC circuit is introduced into feedback, of which R need to meet the conditions:In both the source and small inductance is introduced into feedback to further improve the stability, the value of the inductance to repeatedly adjust the rear can be determined.Introduction of negative feedback circuit simulation again, within its working frequency stability factor K > 1, meet the absolute stability condition.2.4 minimum noise factor input matching circuit is designed, the biggest gain of the output matching circuit designIf the input matching circuit and the output matching circuit of rf devices Zin the input impedance and output impedance Zout impedance Zo are transformed to the standard system, namely the Zin = Zo, Zout = Zo (or, as shown in figure 1) to make a device transport the highest gain. But when input and output matching, noise is not the best. When Γ S = Γ opt, could get the minimum noise figure.ADS can be easily draw power gain and noise coefficient, as shown in figure 3. Can be seen from the diagram, if from m2 point impedance matching to the standard system, will be able to make the circuit gain maximum gain; If impedance matching to the standard system, from the m3 point will be minimal noise coefficient can be obtained. Obviously the biggest gain and the minimum noise figure cannot get at the same time. For low noise amplifier, the first is to consider the minimum noise figure, and so on m3 point matching. Use ADS bring tools "Smith Chart the Utility Tool", in which as long as the set frequency, source impedance and the target impedance value, can the input matching circuit design need.In the input matching is complete, add impedance measurement control measure in principle diagram output impedance, again using "Smith Chart the Utility Tool will impedance, output impedance matching to the standard system can get the maximum gain of the output matching circuit.When the output matching is completed, because has changed from the input to see the equivalent impedance Zin, will get poor return loss at the input. For this purpose, the optimal control can be used for the input and the output matching circuit optimization to improve at the same time, also can use Tunig tools.2.5 the final circuit analysis and simulation resultsMatched and optimized circuit as shown in figure 4, the role of each element in the circuit are respectively: C6, L6 is input matching circuit; C7, is about the output matching circuit; L1, L5, C3, R5 is feedback element; L3, L4 is choke inductance; C4, C5 is the direct coupling capacitance; C1, C2 is the bypass capacitor.Feedback to be sure, inductance L1, L5 and matching circuit element in C6, L6, C7, about because small amounts, such as microstrip line to replace the commonly used in engineering.The simulation results as shown in figure 5. Its working bandwidth of 500 MHz, the center frequency close to 20 dB gain, input and output return loss is less than 10 dB of noise coefficient is less than 0.5 dB, stability factor greater than 1. If disconnect again after feedback circuit simulation, will find the gain increased, but the stability coefficient will be less than 1, the amplifying circuit will not work properly.3 conclusionThrough radio frequency low noise amplifier design and simulation, can see use ADS auxiliary circuit design, the theoretical calculation is simple, rapid design process, parameter modification easy, convenient, shorten the design cycle,
本文借助Agilent公司的射频电路设计软件ADS(Advanced Design System)进行辅助设计一款高增益低噪声放大器(LNA),并对其进行了仿真验证.
1 射频放大器的组成
单级射频放大器的组成如图1所示,包括射频晶体管放大电路和输入、输出匹配网络三部分.
2 射频放大器的设计
2．1 晶体管的选择
选择好晶体管器件对低噪声放大器的设计至关重要.
根据工作频率、增益和噪声系数等指标要求,同时考虑到设计、仿真时便于得到相应的元器件模型,最终选用Avago公司的高电子迁移率晶体管(E-PHEMT)ATF-58143来进行设计(可以在Avago公司的网站上下载到ATF-58143的元件模型).
2．2 偏置电路的设计
设计LNA首先需要确定静态工作点,利用ADS中的“DC_FET_T”的模板可以很方便地仿真出其输出特性曲线.再参考ATF-58143的datash eet,可以确定当Vds=3 V,Ids=35 mA时,各项设计指标满足要求.
确定静态工作点后,就要确定偏置电路的形式和参数.不需人工计算,借助ADS中的设计向导工具(DesignGuide→Amplifier→Tools→ Transistor Bias Utility)可以轻易完成.因为ADS所提供的元件数值是非标称的,所以需要设计者用与ADS提供的数值接近的标称元件进行替代.偏置电路及各点静态参数如图2所示.
2．3 稳定性分析及改善
晶体管绝对稳定的条件是K>1,|△|<1.其中：
如果这两个条件不能同时得到满足,电路将存在潜在的不稳定和振荡的可能.对上述偏置条件下的晶体管进行稳定性仿真分析发现,在要求的工作频段内其稳定系数K<1,不满足绝对稳定的条件.
通过引入负反馈的方式可以改善电路的稳定性,同时也能够拓展工作带宽.在输出端和输入端之间串联RC电路引入负反馈,其中的R需要满足条件：
同时在两个源极加上小的电感引入负反馈进一步改善稳定性,该电感的值需反复调节后方能确定.
对引入负反馈后的电路再次仿真,其工作频带内稳定系数K>1,满足绝对稳定条件.
2．4 最小噪声系数的输入匹配电路设计,最大增益的输出匹配电路设计
如果输入匹配电路和输出匹配电路使射频器件的输入阻抗Zin和输出阻抗Zout都转换到标准系统阻抗Zo,即Zin=Zo,Zout=Zo(或,如图1所示)就可使器件的传输增益最高.但输入、输出匹配时,噪声并非最佳.当ΓS=Γopt时,可以得最小的噪声系数.
利用ADS可以很方便地绘制出等功率增益圆和等噪声系数圆,如图3所示.从图中可以看出,如果从m2点匹配到标准系统阻抗,将可以使电路获得最大的增益；如果从m3点匹配到标准系统阻抗,将可获得最小的噪声系数.显然最大增益和最小噪声系数不可同时得到.对于低噪声放大器,首要的是考虑最小噪声系数,因此对m3点进行匹配.借用ADS的自带工具“Smith Chart Utility Tool”进行,只要在其中设置好频率、源阻抗和目标阻抗值,就可以设计出所需要的输入匹配电路.
在输入端匹配完成以后,在原理图中加入阻抗测量控件测出输出阻抗,再次使用“Smith Chart Utility Tool”将输出阻抗匹配到标准系统阻抗,就可得到最大增益的输出匹配电路.
当输出端的匹配完成后,因为改变了从输入端向里看的等效阻抗Zin,输入端的回波损耗会变差.为此,可以采用优化控件对输入端和输出端的匹配电路进行同时的优化改进,也可以使用Tunig工具进行调节.
2．5 最终电路及仿真结果分析
匹配及优化后的电路如图4所示,电路中各元件的作用分别是：C6、L6是输入匹配电路；C7、L7是输出匹配电路；L1、L5、C3、R5是反馈元件；L3、L4是扼流电感；C4、C5是隔直耦合电容；C1、C2是旁路电容.
需要说明的是,反馈电感L1、L5和匹配电路中的元件C6、L6、C7、L7等因为数值较小,在工程中常用微带线来代替.
仿真结果如图5所示.其工作带宽达500 MHz,中心频率处增益接近20 dB,输入输出反射损耗小于-10 dB,噪声系数小于0．5 dB,稳定系数大于1.如果断开反馈电路后再次仿真,会发现增益有所加大,但稳定系数将小于1,放大电路将不能正常工作.
3 结论
通过射频低噪声放大器的设计与仿真,可以看到使用ADS辅助设计电路,理论计算简单,设计过程快速,参数修改容易,验证方便,缩短了设计周期,提高了设计精度,在工程中具有实用价值.
By a weak signal from the antenna in the rf receiver front-end amplifier amplification, therefore asked the amplifier gain and low noise factor.In this paper, with the aid of Agilent ADS of rf circuit Design software (Advanced Design System) for aided Design a high gain and low noise amplifier (LNA), and the simulation verification.1 the composition of the rf amplifierSingle stage composed of rf amplifier is shown in figure 1, including rf transistor amplifier circuit and the input and output matching network of three parts.2 the design of the rf amplifier2.1 the choice of the transistorGood selection transistor components for the design of the low noise amplifier is very important.According to the working frequency, gain and noise figure index requirements, at the same time when considering the design, the simulation is easy to get the corresponding components model, finally choose Avago company of high electron mobility transistor (PHEMT) E ATF - 58143 for design (can be downloaded on Avago company web site to the ATF components model - 58143).2.2 the design of the bias circuitDesigning LNA first need to determine the static working point, the use of ADS "DC_FET_T" templates can be easily in the simulation of the output characteristic curve. Reference ATF - 58143 again datash eet, can be determined when the Vds = 3 V, Ids = 35 mA, the design indexes meet the requirements.After determine the static working point, shall determine the form and the parameters of bias circuit. Do not need artificial calculation, with the aid of ADS in the design wizard tool (DesignGuide - Amplifier - > Tools - Transistor Bias, the Utility) can be done easily. Because the ADS provided by the component values are nominal, so designers need to use with the ADS provide alternative values close to the nominal elements. Bias circuit and some static parameters as shown in figure 2.2.3 stability analysis and improvementTransistor is K > 1, the absolute and stability of the | delta | < 1. Among them:If the two conditions cannot be satisfied at the same time, there will be potential instability and oscillatory circuit. Transistor of the bias conditions stability simulation analysis found that the stability coefficient within the required working frequency band K < 1, can not meet the needs of absolute stability conditions.By introducing feedback on ways to improve the stability of the circuit, but also can extend working bandwidth. Between the output and the input series RC circuit is introduced into feedback, of which R need to meet the conditions:In both the source and small inductance is introduced into feedback to further improve the stability, the value of the inductance to repeatedly adjust the rear can be determined.Introduction of negative feedback circuit simulation again, within its working frequency stability factor K > 1, meet the absolute stability condition.2.4 minimum noise factor input matching circuit is designed, the biggest gain of the output matching circuit designIf the input matching circuit and the output matching circuit of rf devices Zin the input impedance and output impedance Zout impedance Zo are transformed to the standard system, namely the Zin = Zo, Zout = Zo (or, as shown in figure 1) to make a device transport the highest gain. But when input and output matching, noise is not the best. When Γ S = Γ opt, could get the minimum noise figure.ADS can be easily draw power gain and noise coefficient, as shown in figure 3. Can be seen from the diagram, if from m2 point impedance matching to the standard system, will be able to make the circuit gain maximum gain; If impedance matching to the standard system, from the m3 point will be minimal noise coefficient can be obtained. Obviously the biggest gain and the minimum noise figure cannot get at the same time. For low noise amplifier, the first is to consider the minimum noise figure, and so on m3 point matching. Use ADS bring tools "Smith Chart the Utility Tool", in which as long as the set frequency, source impedance and the target impedance value, can the input matching circuit design need.In the input matching is complete, add impedance measurement control measure in principle diagram output impedance, again using "Smith Chart the Utility Tool will impedance, output impedance matching to the standard system can get the maximum gain of the output matching circuit.When the output matching is completed, because has changed from the input to see the equivalent impedance Zin, will get poor return loss at the input. For this purpose, the optimal control can be used for the input and the output matching circuit optimization to improve at the same time, also can use Tunig tools.2.5 the final circuit analysis and simulation resultsMatched and optimized circuit as shown in figure 4, the role of each element in the circuit are respectively: C6, L6 is input matching circuit; C7, is about the output matching circuit; L1, L5, C3, R5 is feedback element; L3, L4 is choke inductance; C4, C5 is the direct coupling capacitance; C1, C2 is the bypass capacitor.Feedback to be sure, inductance L1, L5 and matching circuit element in C6, L6, C7, about because small amounts, such as microstrip line to replace the commonly used in engineering.The simulation results as shown in figure 5. Its working bandwidth of 500 MHz, the center frequency close to 20 dB gain, input and output return loss is less than 10 dB of noise coefficient is less than 0.5 dB, stability factor greater than 1. If disconnect again after feedback circuit simulation, will find the gain increased, but the stability coefficient will be less than 1, the amplifying circuit will not work properly.3 conclusionThrough radio frequency low noise amplifier design and simulation, can see use ADS auxiliary circuit design, the theoretical calculation is simple, rapid design process, parameter modification easy, convenient, shorten the design cycle,