非连续线性啁啾取样布拉格光栅型多信道光纤滤波器的设计

介绍了一种基于取样布拉格光纤光栅获得多信道光纤滤波器的方法。通过设计一种非连续阶梯型啁啾取样的布拉格光栅结构,可以分别实现单个信道宽度为50,100和200GHz的光纤滤波器。光纤滤波器的每个信道的宽度几乎完全相同,具有平顶、峭沿和高透射率特点,相邻信道间隔离深度超过28dB,平均插入损失不超过0.1dB,3dB带宽内相位响应起伏在5～30ps。利用介绍的方法制作具有相应非连续线性啁啾系数的全息相位掩模板,易于制作,成本低,重复性好。通过改变相应的光纤光栅参数,可以实现不同信道宽度的,性能稳定、可重复性高的光纤滤波器,在高速光通信系统以及光互连中有着非常好的应用前景。     

片上集成MEMS射频滤波器

研究采用MEMS工艺技术制造可在硅集成电路片上集成的射频滤波器.MEMS工艺技术实现了高性能嵌入式螺管电感和金属-绝缘层-金属电容元件的集成制造.整个微加工制造工艺为低温工艺,可与CMOS集成电路工艺实现后端集成.基于此工艺,设计和实现了应用于5 GHz射频频段的微小化的片上集成滤波器,包括一种低通滤波器和一种带通滤波器.测试结果表明,5阶低通滤波器的 -1.5 dB 转折频率在5.3 GHz频率,从直流到5 GHz频率的插入损耗小于1.06 dB.实现的带通滤波器为两阶谐振耦合式,在中心频段5.3 GHz的最小插入损耗为4.3 dB,通带内的回波损耗大于13 dB.研究结果表明:该微加工技术适用于无源器件和滤波器电路的CMOS后端集成,适合高性能射频片上系统的应用.     

50 omega characteristic impedance low-pass metal powder filters

We have fabricated several 50 omega characteristic impedance low-pass metal powder filters. The filters are made with bronze or copper metal powder with varying amounts of metal powder in a metal powder/epoxy mixture. Our goal is to make a filter with a characteristic impedance Z = 50 omega at frequencies up to 10 GHz. Using a 78% bronze powder/epoxy mixture in a suitable geometry, we achieved an impedance Z = 54 omega at 4.2 K, with a cutoff frequency fc approximately/= 0.3 GHz and an attenuation A = Vout/Vin=0.0001 (-80 dB) at 10 GHz. We also made several non-50 omega low-pass bronze powder filters with fc = 1 MHz and A = 0.0001 at 10 MHz. Fabrication details and performance data will be presented for both types of filter.     

电压模式双二阶跨导线性滤波器

提出了一种新颖的基于线性跨导的双二阶电压模式滤波器,该滤波器采用单端输入五端输出的结构形式,由6个MOCCCⅡ（多端输出的电流控制电流传输器）和2个接地电容构成。在不改变电路内部结构的情况下,该滤波器能同时实现高通、低通、带通、带阻、全通滤波功能,滤波器的参数可以通过改变MOCCCⅡ的偏置电流实现电动调节,且品质因数和中心频率独立可调。面向实际电路进行了硬件实验,结果表明本文提出的电路正确有效。     

单MOCCII多功能电流模式二阶滤波器

本文提出一种单MOCCII多功能电流模式二阶滤波器结构电路。陔电路结构简单，仅由单个MOCCII有源器件及4个RC无源元件构成，能产生二阶低通、带通及高通滤波器，最后对各滤波器进行了硬件实验。     

A fiber loop mirror temperature sensor demodulation technique using a long-period grating in a photonic crystal fiber and a band-pass filter

A fiber loop mirror (FLM) temperature sensor using a long-period grating (LPG) written in a photonic crystal fiber (PCF) and a band-pass filter as a demodulator is proposed. By utilizing the stable filtering function of the LPG in the PCF, the resonant wavelength variation of the FLM with temperature is transferred effectively to the intensity variation of the output light. By monitoring the light intensity of the band-pass of the filter, temperature applied on the FLM is deduced by an optical power meter. Experiment results show that the temperature sensitivity is high as ~1.742 dB/ °C when a filter with a full width at half maximum 3 nm and the center at 1545 nm is used.     

基于双微环结构的MZI型波长交错滤波器

为了改善全光纤马赫-曾德尔干涉仪(Mach-Zehnder interferometer,MZI)的传输特性,提出了一种基于双微环辅助型的MZI交叉复用器。根据其结构,利用信号流图推导出了该器件的输出表达式,并进行了数值模拟分析,得到了传输过程中的最佳结构参数。此外,还分析了耦合器耦合系数及传输损耗对该器件的影响。结果表明,改进后的MZI交叉复用器输出谱线更加接近方波,其25 dB截止带带宽和0.5 dB通透带带宽明显改善,其值分别为41.2 GHz和18.9 GHz。器件具有一定的抗偏差能力且传输损耗对滤波器消光特性的影响较小。     

基于波导功分馈电的CTS阵列天线设计

本文设计了一种具有高增益、高效率、低损耗特性的16单元连续横向枝节(continuous transverse stub,CTS)天线阵列。该天线的辐射枝节部分采用了串联的结构来降低损耗,从而提高辐射效率,并且使用了功率分配器和辐射器组合的方式给CTS阵列天线进行馈电,改善了CTS阵列天线的阻抗匹配和方向性,使天线可以在双频段工作。对设计的天线采用电磁仿真软件HFSS进行仿真优化,仿真结果表明,CTS阵列天线在75～80 GHz和85～89 GHz双频带内S11值小于-10 dB,工作频率在78.8 GHz时增益为28.6 dB,在87.5 GHz时增益为28.4 dB,天线效率均超过50%,主瓣波束宽度为4.4°。     

基于Serenade软件的微带线带通滤波器的优化设计

应用Ansoft公司的Serenade 8.71微波仿真软件,设计和优化了一种中心频率为1GHz的微带线平行耦合带通滤波器。结果表明,利用该软件设计出的滤波器完全符合设计要求,而且方便、快速,适用于工程设计。     

Fabrication and characteristics of mesh band-pass filters

Mesh band-pass filters for 300-, 450-, 600-, and 750-GHz central frequencies are designed and manufactured. Copper and aluminum foil and foil-clad Teflon filters were made by chemical and ionic etching methods, and an aluminum film evaporated on a kapton film was formed by the lift-off lithography method. A gold layer was electrolytically applied on copper mesh filters. Characteristics of the filters were measured in the millimeter, submillimeter, and infrared (IR) ranges. Foil filters demonstrate better characteristics at lower frequencies, while filters with evaporated films have better characteristics at upper frequencies. The smallest transmission loss was 0.13 dB. For a combination consisting of four filters, this loss was 0.9 dB. The IR radiation attenuation in a 2.5- to 25.0-μm wavelength region was no less than 11 dB per filter.     

一种MOCCII通用电流模式滤波器的实现

提出一种结构简单、易于实现的基于 MOCCII(多输出端第二代电流传输器 )的单输入多输出的通用电流模式滤波器电路 ,该滤波器电路仅由 3个 MOCCIIs及 6个接地 RC元件构成 ,能同时输出低通、带通、高通、带阻及全通五种滤波形式 ,具有很低的无源灵敏度 ,且所有的 RC元件均接地。给出了硬件电路的实验结果。     

基于固体腔的超窄带F—P干涉滤光片

介绍了一种利用熔融石英作为间隔层来实现F-P超窄带干涉滤光片的设计原理与方法。并制备了半宽2nm,透射率约90%的滤光片。该滤光片间隔层的干涉级次很高,能有效压缩带宽,实现超窄带滤波,不但极大提高了峰值透射率,而且温度稳定性好。     

基于HWPT-ZFFT的二维全息谱计算方法

精确的频率、相位和幅值识别是进行全息谱计算的必备条件,针对含3个及以上的密集频谱成分,提出一种基于谐波小波包变换的频谱细化方法(harmonic wavelet packets transform-zoom fast Fourier transform,简称HWPT-ZFFT),较传统的复调制细化傅里叶变换所利用的低通及带通滤波器相比,其盒型频谱特性可将感兴趣频段的信号正交,无冗余、无泄漏地提取出,提高了识别精度。首先,利用谐波小波包对密集频谱成分进行滤波;然后,频移进而重采样,进行傅里叶变换得到细化的频率、幅值及相位;最后,计算密集频率下二维全息谱,进行双盘转子全息谱计算,考虑高次分倍频,得到更丰富的故障特征。仿真及双盘转子实验结果表明所提出方法的有效性。     

低驱动电压两端固定"桥"式RF MEMS开关的研制

文中介绍了一低驱动电压接触式RF-MEMS开关,开关采取了两端固定的"桥式"结构,在桥与支撑点间采用折叠弯曲的铰链结构,而且紧靠中央信号线的旁边各有一个较大面积的电极,这些措施降低了开关的驱动电压.整个工艺采用表面微加工工艺.由实验测试可知:开关驱动电压11 V左右,与ANSYS模拟的值12 V基本一致,开关的S参数,在的范围内,插入损耗要小于-1 dB,在频段(≤5 GHz),开关的隔离度要优于-30 dB,在频段5～10 GHz,隔离度也要高于-20 dB.     

程控滤波器系统设计

系统实现了10 mV的微弱信号的程控放大和程控高低通滤波,其中程控放大利用AD620放大器和LF351实现两级增益放大,用6个继电器控制反馈电阻实现输出增益0 dB到60 dB可调;放大信号通过低通或者高通电压控制电压源(VCVS)滤波器,滤波器的截止频率从1 kHz到20 kHz可调。系统以MEGA16为控制核心,用继电器实现硬件电路的切换从而使增益可调,并设计了一个通带为50 kHz的四阶椭圆低通滤波器,滤波器的参数通过计算和PSPICE仿真结合得到,并在测试过程中修正相关参数。该系统思路简单易于实现,且各参数的误差较小。     

应力变化对多层薄膜窄带滤光片透射光谱的影响

利用薄膜应力公式和弹性力学的小挠度弯曲理论分析了在应力变化情况下,多层薄膜应变与膜厚变化的关系,并建立其数学模型,提出多层薄膜各层厚度变化的不均匀性理论.利用这个模型在应力减小200MPa条件下对138层4腔的100GHz滤光片光谱进行了模拟,与设计值比较发现中心波长增加了0.562nm;0.5dB处的带宽比设计值减小0.124nm;25dB处的带宽比设计值减小0.01nm;谱线矩形化变差;插损也有明显的增加.说明了应力变化引起的光学薄膜厚度变化的不均匀性是引起这种窄带干涉滤光片光谱退化的主要原因之一.实验结果为100GHz的窄带滤光片热处理后中心波长增加0.325nm;0.5dB处带宽减少0.01nm;20dB处带宽增加0.014nm;插损增加,谱线通带变形严重,纹波增大,光谱退化了.实验结果与理论分析一致.     

用IAD法制作的高密集型分波复合器滤光片的特性

随着高密集型分波复合器需要的不断增加,在光纤通讯领域中,光学薄膜滤光片已经成为了一个很关键的光学元件。在高密集分波复合器中,我们用ＩＡＤ方法制作了低损失、高稳定性的超窄带滤光片并在本文加以讨论。在湿度环境试验中,这种高堆积密度的光学薄膜显示了没有任何波漂。在温度环境试验中,它的热稳定性为０．００１２ｎｍ ／℃。在使用Ｔａ２Ｏ５／ＳｉＯ２,用于１００ＧＨｚ的滤色片的场合下,窄带滤色片的插入损失为０．３４ｄＢ。在使用Ｎｂ２Ｏ５／ＳｉＯ２,用于２００ＧＨ２ 的滤色片的场合下,插入损失为０．１７ｄＢ,两者都显示了极好的分光光谱特性,甚至半宽为０．６６ｎｍ 的情况下,它们的截面ＳＥＭ 微结构显示了非晶结构,平坦的表面与界面。     

First experimental demonstration of a photonic band gap channel-drop filter at 240 GHz

We have designed, fabricated, and tested a novel photonic band gap (PBG) channel-drop filter (CDF) operating at around 240 GHz. A PBG CDF is a device that allows the channeling of selected frequencies from continuous spectra into separate waveguides through select defects in a PBG structure. It is compact and configurable, and thus, it can be employed for millimeter-wave spectrometry with applications in communications, radio astronomy, and radar receivers for remote sensing and nonproliferation. In this paper we present the design, modeling, and fabrication methods used to produce a silicon-based PBG CDF, and demonstrate its ability to filter the frequency of 240 GHz with a linewidth of approximately 1 GHz and transmission of 25 dB above background.     

Filter with variable transmission characteristics for determination of three-dimensional roughness

In this study, we propose a low-pass filter whose transmission characteristics are determined to be more than 99.99% identical to the designed transmission characteristics at wavelengths greater than the cut-off wavelength. This low-pass filter is realized using a frequency-domain method which uses down-sampling, a frequency filter, and a cubic B-spline. When the frequency characteristics of a Gaussian filter (GF) were used as the designed transmission characteristics, this low-pass filter perfectly replaced the GF. In addition, no end effects and directional characteristics developed, and high-speed computation was possible. Furthermore, we can easily realize a low-pass filter having transmission characteristics that rise sharply at a right angle like a step edge.     

Broadband notch filter design for millimeter-wave plasma diagnostics

Notch filters are integrated in plasma diagnostic systems to protect millimeter-wave receivers from intensive stray radiation. Here we present a design of a notch filter with a center frequency of 140 GHz, a rejection bandwidth of ～900?MHz, and a typical insertion loss below 2 dB in the passband of ±9 GHz. The design is based on a fundamental rectangular waveguide with eight cylindrical cavities coupled by T-junction apertures formed as thin slits. Parameters that affect the notch performance such as physical lengths and conductor materials are discussed. The excited resonance mode in the cylindrical cavities is the fundamental TE(11). The performance of the constructed filter is measured using a vector network analyzer monitoring a total bandwidth of 30 GHz. We compare the measurements with numerical simulations.