Ka波段硅基MEMS滤波器

滤波器是微波毫米波电路中的一个重要部件,本文介绍了采用基片集成波导技术和ICP深刻蚀微机械通孔阵列的硅基MEMS滤波器.设计制作了MEMS滤波器的核心部件谐振器,测试结果显示该谐振器无载Q值大于180,频率误差控制在2%以内.以此为基础采用理论计算与实验设计相结合的方法设计了一个Ka波段硅基MEMS滤波器.滤波器中心频率为30.3 GHz,插入损耗1.5 dB,相对带宽5%.芯片尺寸为10.0 mm×2.8 mm×0.4 mm.     

RF-MEMS滤波器的高性能接口电路设计

提出了一种适用于射频-微机电系统(RF-MEMS)滤波器的高性能接口放大电路.利用微纳工艺制备了相对带宽为1.4％、中心频率为73.02 MHz的硅基MEMS滤波器,针对其高阻抗、高插入损耗特性,设计了基于运算放大器的低噪声、高增益的两级放大电路和阻抗匹配电路.仿真结果表明:接口电路对高频的MEMS滤波器微弱电流信号具...     

梳状线可调带通滤波器的设计与仿真

针对现有的微带可调滤波器中心频率调节范围较窄的问题,依据梳状滤波器的原理和变容二极管的特性,设计出一种梳状线可调带通滤波器,经ADS仿真可得其中心频率可调范围达到0．49～5．08GHz、相对带宽仅为6．1％～9．4％,该梳状线可调带通滤波器具有中心频率调节范围很宽、结构简单、易于实现、易于扩展等优点,在工程上具有一定的推广应用价值。     

基于共平面波导的可调低通滤波器的设计和制作

介绍了一种使用多触点MEMS开关实现的新型可调微波MEMS低通滤波器,应用MEMS制作工艺在石英衬底上实现滤波器结构.滤波器基于慢波共平面波导周期性结构,具有尺寸小、插损低、可与单片微波集成电路工艺兼容等优点.滤波器截止频率的大小取决于MEMS开关的状态.实验结果表明,当MEMS开关受到激励时,低通滤波器的3-dB截止频率从12.5GHz转换至6.1GHz,带内纹波小于0.5dB,带外抑制大于40dB,开关的驱动电压在25V左右.     

程控开关电容低通滤波器的通用模块开发

滤波器在电子学噪声测量和谐波失真测量的过程中,用于获取特定频带的信号或者抑制噪声。开发了一种带宽可调的程控开关电容低通滤波器模块,采用STM32单片机输出频率可调的时钟信号控制滤波器截止频率,改善了现有滤波器因参数固定而不能调节动态频率范围的情况。实验结果表明该程控滤波器通带在10 Hz～40 kHz可调,对频带外信号有明显的抑制能力,满足设计需求。     

基于铣削式加工的140 GHz矩形波导带通滤波器

利用现代计算机数控机床（Computer Numerical Control,CNC）铣削技术实现了中心频率为140 GHz的矩形波导带通滤波器。基于电磁仿真软件HFSS对该滤波器进行了优化设计和容差分析。采用CNC铣削技术完成了该滤波器的加工制备。测试结果与仿真结果吻合良好，表明该滤波器具备优越的性能：其中心频率为140.2 GHz、3 dB相对带宽为10.1%，插入损耗小于0.5 dB，带内回波损耗优于25 dB，距中心频率±20 GHz处带外抑制大于30 dB。该结果进一步验证了利用CNC铣削技术加工140 GHz波段滤波器的可行性。     

基于FFP可调滤波器的FBG解调系统设计

提出并实现了一种基于FFP可调滤波器的FBG解调系统.该系统通过PC104嵌入式系统控制的D/A输出信号,作为可调滤波器的控制信号,对光纤上的所有光栅连续扫描以实现波长信号的解调.该解调系统扫描带宽50 nm,以10 Hz频率进行扫描,可以得到稳定的测量信号.     

一种基于体硅工艺的微机械可调节椭圆低通滤波器

提出了一种椭圆低通可调滤波器的调谐方法,即通过调节第一传输零点(FTZ)来改变3 dB截止频率Tc.解析计算表明,小范围内改变FTZ既可调节Tc和滚降速率,又能保证通带和阻带的特性基本不变.作者提出FTZ的移动可由串联谐振支路处容性MEMS开关的分布加载来实现,并基于微扰法求出器件中心谐振频率及特性的变化规律.本文相应设计了Tc为16 GHz的7阶步进式滤波器.高频有限元全波仿真表明,每加载一个MEMS开关,Tc改变约1.5 GHz,损耗特性则几乎不变.这证明了理论分析方法有较高的准确性,而且器件设计具有数字化调节能力和较出色的微波性能.这种方法也可用于高通和带通滤波器.论文还介绍了器件的体硅微加工流程及MEMS开关的初步加工结果.     

SIW交指带通滤波器的设计及仿真

介绍了一种双层SIW带通滤波器,两层之间采用交指结构实现谐振,输入输出采用共面波导形式.所设计的毫米波滤波器芯片尺寸仅有7 mm×3.5 mm×0.8 mm,使用三维高频电磁仿真软件对该结构进行仿真和优化,结果表明滤波性能符合设计要求:中心频率10.6 GHz、带宽2.5 GHz、带内插损2 dB.最后阐明了基于MEMS技术的该滤波器的工艺制作流程.     

基于MEMS滤波器芯片的X波段混频通道设计

提出了基于MEMS滤波器芯片进行X波段接收模块小型化设计的方法,构成下变频电路,与本振功分电路、电源控制电路完成放大、滤波和增益控制功能,实现由X波段到L波段中频的小体积、低功耗四路下变频接收通道。利用电路分析与建模仿真,分解各部分电路的技术指标。各部分电路中最关键的是下变频电路,即混频放大链路,其中的射频开关滤波器和中频滤波器对通道整体性能至关重要,因此可以采用MEMS滤波器芯片设计来实现。MEMS滤波器芯片在性能、体积方面具有明显优势,用以实现的单路混频通道结构紧凑、功耗低,满足小型化、模块化和集成化的技术趋势与需求,适合在实际应用中推广。     

Inductively‐loaded RF MEMS reconfigurable filters

This article presents an inductively loaded radio frequency (RF) microelectromechanical systems (MEMS) reconfigurable filter with spurious suppression implemented using packaged metal‐contact switches. Both simulation and measurement results show a two‐state, two‐pole 5% filter with a tuning range of 17% from 1.06 GHz to 1.23 GHz, an insertion loss of 1.56–2.28 dB and return loss better than 13 dB over the tuning range. The spurious passband response in both states is suppressed below ?20 dB. The unloaded Q of the filter changes from 127 to 75 as the filter is tuned from 1.06 GHz to 1.23 GHz. The design and full‐wave simulation of a two‐bit RF MEMS tunable filter with inductively loaded resonators and monolithic metal‐contact MEMS switches is also presented to prove the capability of applying the inductive‐loading technique to multibit reconfigurable filters. The simulation results for a two‐bit reconfigurable filter show 2.5 times improvement in the tuning range compared with the two‐state reconfigurable filter due to lower parasitics associated with monolithic metal‐contact MEMS switches in the filter structure. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Variable bandwidth,wide tunable frequency,voltage tuned filter

This article discusses the development of an electronically tuned filter capable of a wide tunable frequency range and simultaneous 3-dB bandwidth variations at any frequency within its tuning range. Varactor-tunable filters are designed using high-dielectric, soft-substrate material for printed resonators as well as also high-Q ceramic resonators, and their test data are compared. Greater than 50% tuning range with low insertion loss at a center frequency in the L and S frequency bands is demonstrated with a 4:1 change in 3-dB bandwidth—30 to 120 MHz for printed resonators and 14 to 46 MHz for ceramic resonators. The concept of tuning a filter's 3-dB bandwidth with voltage is demonstrated and the effect of the bandwidth tuning elements on the tunable filter performance is discussed. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 64–72, 2004.     

Design and process considerations for fabricating RF MEMS switches on printed circuit boards

Design considerations and process development for fabricating radio frequency microelectromechanical systems (RF MEMS) switches on microwave laminate printed circuit boards (PCBs) are presented in details in this work. Two key processes, high-density inductively coupled plasma chemical vapor deposition (HDICP CVD) for low-temperature silicon nitride deposition, and compressive molding planarization (COMP) have been developed for fabricating RF MEMS switches on PCB. The effects of process conditions of HDICP CVD on low-temperature nitride film are fully characterized for its use in RF MEMS switches on PCB. Not only can COMP planarize the surface of the photoresist for lithographic patterning over topologically complex surfaces, but also simultaneously create a membrane relief pattern on the surface of a MEMS structure. Several membrane-type capacitive switches have been fabricated showing excellent RF performance and dynamic responses similar to those on semiconductor substrates. This technology promises the potential of enabling further monolithic integration of switches with other RF components, such as antennas, microwave monolithic integrated circuits (MMICs), phase shifters, tunable filters, and transmission lines on the same PCBs reducing the losses due to impedance mismatching from components/system assembly and simplifies the design of the whole RF system. [1416].     

零谱矩滤波器系列

鉴于一种新型的滤波器类别———零谱矩滤波器系列,其性能优于传统信号处理中的FIR滤波器,特别在通带的平滑度与阻带的衰减度方面尤佳。其特例包含了人们熟识的小波变换滤波器,如共轭滤波器与双正交滤波器。为此,对其进行简要介绍,以飨读者。     

Optimal electrode shaping for precise modal electromechanical filtering

This paper addresses the optimal shape design of segmented spatial sensors and actuators that isolate selected mode shapes and perform modal filtering. Electromechanical filters have reappeared with the new manufacturing capabilities of micro-electro-mechanical structures (MEMS). In such small dimensions it proves essential to treat their elastic behaviour as continuous rather than discrete systems that require suitable design methods, some of which are developed here. In MEMS filters, the input signal is converted to external electrostatic forces and in order to perform the desired filtering, the electrodes need to be shaped such that they excite only a desired part of the dynamics. An optimization scheme that shapes these electrodes to achieve optimal filtering is developed. In order to enhance the filter’s performance and minimize energy lost to the supporting structure, a special support tuning method is proposed. Several simulated examples examine the effectiveness of the proposed optimization methods.     

MEMS switches controlled multi-split ring resonator as a tunable metamaterial component

Based on the multisplit-ring resonator (MSRR) with MEMS switches, a tunable metamaterial component is proposed in this paper to realize multiband applications. Numerical simulations are carried out to verify the tunable capacity of the proposed structure. The simulated results show that the resonance frequency of the metamaterial component shifts to higher frequencies when the MEMS switches are at different states, and depends strongly on the place, state and microbeam height of MEMS switches. Moreover, the large tunable range can be obtained by controlling the up state or down state of MEMS switches, while the small tunable range can be obtained by controlling microbeam height of MEMS switches. That is, such controlling ways can realize both rough and minor tunable metamaterial component. The tunable method proposed in this paper is of great practical values in designing tunable metamaterial and negative refractive index material.     

Effect of filter parameters on the phase noise of RF MEMS tunable filters employing shunt capacitive switches

The effect of filter parameters on the phase noise of RF MEMS tunable filters employing shunt capacitive switches is investigated in this article. It is shown that the phase noise of a tunable filter is dependent on the input power, fractional bandwidth, filter order, resonator quality factor, and tuning state. Phase noise is higher for filters with smaller fractional bandwidth. In filters with high fractional bandwidth (>3%), phase noise increases as the input power approaches the power‐handling capability of the filter. In filters with smaller bandwidths, phase noise increases with input power upto a threshold level of input power, but begins to decrease thereafter. The unloaded quality factor of the filter has a noticeable effect on the phase noise of filters with narrow bandwidths. The phase noise changes with the filter tuning state and is maximum when all the switches are in the up‐state position. It is also shown that the phase noise increases with the filter order, due to increase in the number of noisy elements in the filter structure. This article provides a methodology to evaluate the phase noise of a tunable filter and proves that RF MEMS filters are suitable for high performance applications without considerable phase‐noise penalty. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

Synthesis and design of tunable bandpass filters with constant absolute bandwidth using varactor‐loaded microstrip resonator

This article presents two new types of tunable filters with constant absolute bandwidth using varactor‐loaded microstrip resonators. First, the second‐ and third‐order Butterworth tunable filters are designed based on the parallel coupled‐line J inverters. Second, a fourth‐order Chebyshev tunable filter is designed based on the alternative J/K inverters, in this design, two adjacent resonators are coupled with each other through a short‐circuited transmission line as the K inverter. The proposed two topologies can be easily extended to high‐order tunable filter. Three tunable bandpass filters with J and alternative J/K inverters, respectively, are built with a tuning range from ～1.8 to ～2.3 GHz. The measured second‐order filter has a 3‐dB bandwidth of 160 ± 6 MHz and an insertion loss of 2.4–3.8 dB. The third‐order filter shows a 3‐dB bandwidth of 197 ± 5 MHz and an insertion loss of 3.8–4.8 dB. The fourth‐order filter shows a 3‐dB bandwidth of 440 ± 5 MHz and an insertion loss of 2.1–2.6 dB. For all the designed filters, the measured results are found in excellent agreement with the predicted and simulated results. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:681–689, 2014.     

An eclectic approach to design tunable amplifiers

Broadband amplifiers that can accommodate commercial communication standards such as GSM, UMTS, Wi‐Fi, and Wi‐Max are extremely important for radio equipment manufacturers. To achieve this coverage, the amplifier should provide high gain and efficiency over a band from 800 to 5200 MHz. Although there are transistor devices that have cut‐off frequencies well over these frequencies, amplifiers covering such a broad‐bandwidth are difficult to design due to the requirement of broadband matching networks. In this work, design of broadband tunable matching networks is investigated using Real Frequency Direct Computational Technique (RF‐DCT). In order to be able to work on sample structures, impedance transforming filters are chosen and a broadband tunable matching network has been designed. Implementation of tunable inductors is investigated and the performance of a tunable matching network using tunable inductors and capacitors is demonstrated. Eventually a broadband frequency tunable amplifier has been designed using the tunable inductor concept. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.