滤波器的发展及应用

随着通讯技术的不断发展,作为通讯系统中的一种不可缺少的器件——滤波器,近年来发展很快。滤波器是一种对频率具有选择性的复杂网络,它对某一频率范围内的信号给以很小的衰减,使这部分信号能够顺利通过,对其它频     

差分LC滤波器在通信电路中的设计和应用

差分信号在无线通信系统链路中应用越来越广泛,模拟的差分LC滤波器可以有效抑制射中频电路中的带外谐波和噪声等无用信号。文章提出差分LC滤波器设计途径和单端LC滤波器简单的转换关系,介绍了射中频差分LC滤波器在无线通信系统中的一些应用问题。     

有源电力滤波器控制技术现状及发展

伴随着电力电子技术的飞速发展以及广泛应用,在提高输电效率的同时,其带来的弊端也日益凸显,最严重的是造成了电网中的谐波污染,对电力系统的运行、电能的生产及输送都造成很大的危害。现如今治理谐波最有效的方法之一就是使用有源电力滤波器对谐波电流进行补偿。该文对有源电力滤波器的工作原理、分类、控制技术现状以及应用前景进行阐述。     

TDD-LTE终端二次谐波的抑制

二次谐波是器件非线性造成的,为了有效的抑制二次谐波对其它频率的干扰,本文主要通过设计LC滤波器,解决TDD—LTE的二次谐波问题。     

混合型电力滤波器在充电桩建设中的应用

为了解决充电站充电过程中所产生的谐波问题,本文首先对充电站的谐波特点进行简要分析,然后根据充电站谐波特点,设计了一种混合型电力滤波器对充电站的谐波进行抑制,最后在simulink的仿真平台进行仿真验证。仿真结果表明,混合型电力滤波器能够有效的抑制谐波     

基于FPGA的高效可调频率滤波器

为了有效地改善滤波器的不可调频率系统性能,降低FPGA滤波器资源的消耗,提出基于FPGA的高效可调频率滤波器。该方法首先对可调频率滤波器进行硬件平台设计,硬件平台由单片机模块、FPGA波形模块、幅度模块、数字模型转换模块、低通滤波转换模块以及输入键盘模块和液晶显示屏模块构成。核心模块由MCU提供可调频率控制,以DDS技术产生的波形信号为依据,确定滤波器的信号强度,最后采用分布算法完成滤波器软件设计。实验证明,所提方法能够有效提高可调频率滤波器的准确度。     

有源电力滤波器的研究热点和发展

有源电力滤波器研究已成为目前国内外供电系统谐波抑制研究的热点。本文首先介绍了两种谐波治理的措施。然后重点对有源电力滤波器研究中的拓扑结构、检测和控制理论、数字化控制技术发展等研究热点进行介绍和分析。最后指出了有源电力滤波器今后发展的一些主要方向。[编者按]     

可调增益程控滤波器的设计

介绍一款用于处理含有噪声和干扰的微弱信号的可调增益程控滤波器,程控放大部分由AD7520内部集成的电阻网络和运算放大器AD826组成,程控滤波部分由可编程控制滤波器芯片MAX261来完成,用单片机89c51作为控制器,对程控增益部分和程控滤波进行编程控制其增益和滤波频率,同时配合键盘和显示部分完成设定和显示当前的设定,能够对带噪声的微弱信号进行放大和处理。     

滤波器的特点及应用

滤波器是一种对频率具有选择性的复杂网络，它把有用的频率信号保留，无用的频率信号滤除。滤波器的种类较多，各类滤波器都有各自的特点。本文主要介绍LC滤波器、晶体滤波器、声表面波滤波器的特点及应用。1．LC2波器LC滤波器由电感器和电容器组成，分为低通、高通、带通和带阻滤波器。LC滤波器由若干个基本节（T型、H型）或半节（L型）按匹配原则连接而成，如图1所示。基本节又分为常K型和M导出型。LC滤波器图ILC滤波器的基本节应用广泛，工作频率约从几百赫至几十兆赫，且成本低。缺点是工作频率不够高，电感线圈的体积大，品质…     

SPWM逆变电源LC滤波器的研究与设计

为了使基于SPWM的逆变器输出较好的正弦波形,针对SPWM逆变器的谐波特点,采用单级LC低通交流输出滤波网络.为使滤波器传送较多的有功功率,而返回逆变器的无功功率较少,同时将特定次谐波含量控制在设定的范围内,提出了一种单级LC滤波器的设计方法,根据该方法选择滤波器的L、C参数,可以有效控制谐波含量和逆变器的无功功率,得到较好的正弦波形输出.     

可调谐光滤波器的研究

可调谐滤波器在光纤通信和光纤光栅传感中发挥了重要的作用.分别介绍了几种常用的可调谐光滤波的原理、结构和性能,分析了其发展趋势.     

Electronically tunable time-multiplexed active filters

A simple modification of the time-multiplexed active filter allows the transfer function to be electronically tuned. The method is to allow the switched memoryless active subnetwork to be multiplexed in such a way that a variable time slot is allocated to each stage of the filter. Electronic variation of this time slot achieves a corresponding tuning of the transfer function. In terms of circuitry, a simple modification to the logic drive circuitry is required to make tuning possible.     

Electronically switchable and tunable coplanar waveguide-slotlineband-pass filters

A coplanar waveguide (CPW)-slotline bandpass filter is described. The circuit allows planar integration of active and passive semiconductor devices both in series and in shunt. A microstrip-to-slotline transition designed to test the filter is also described. Two of the transitions exhibit an insertion loss of less than 1.0 dB over the 2.0-4.0-GHz range. A three-section CPW-slotline bandpass filter demonstrates an insertion loss of less than 0.2 dB over the passband centered at 2.9 GHz. A three-section CPW-slotline switchable bandpass filter integrated with three p-i-n diodes is discussed. It has a 0.7-dB insertion loss in the passband when the p-i-n diodes are off and a 25.0-dB isolation across the entire band when the p-i-n diodes are on. A three-section CPW-slotline varactor-tunable filter integrated with three varactor diodes is presented, showing a 2.0-dB insertion loss and over 20% electronic tuning range. Simple transmission line circuit models are used to optimize the design     

Miniature and tunable filters using MEMS capacitors

Microelectromechanical system (MEMS) bridge capacitors have been used to design miniature and tunable bandpass filters at 18-22 GHz. Using coplanar waveguide transmission lines on a quartz substrate (/spl epsiv//sub r/ = 3.8, tan/spl delta/ = 0.0002), a miniature three-pole filter was developed with 8.6% bandwidth based on high-Q MEMS bridge capacitors. The miniature filter is approximately 3.5 times smaller than the standard filter with a midband insertion loss of 2.9 dB at 21.1 GHz. The MEMS bridges in this design can also be used as varactors to tune the passband. Such a tunable filter was made on a glass substrate (/spl epsiv//sub r/ = 4.6, tan/spl delta/ = 0.006). Over a tuning range of 14% from 18.6 to 21.4 GHz, the miniature tunable filter has a fractional bandwidth of 7.5 /spl plusmn/ 0.2% and a midband insertion loss of 3.85-4.15 dB. The IIP/sub 3/ of the miniature-tunable filter is measured at 32 dBm for the difference frequency of 50 kHz. The IIP/sub 3/ increases to >50 dBm for difference frequencies greater than 150 kHz. Simple mechanical simulation with a maximum dc and ac (ramp) tuning voltages of 50 V indicates that the filter can tune at a conservative rate of 150-300 MHz//spl mu/s.     

Electrooptic tunable filters for infrared wavelengths

This paper describes the performance characteristics of an electronically tunable infrared filter based on the electrooptic effect. Like the acoustooptic tunable filter, this device operates by selectively coupling principal polarizations in a birefringent crystal at a Phase-matched wavelength by means of a spatially periodic refractive index perturbation. Instead of a traveling acoustic wave, however, the electrooptic tunable filter employs a temporally static electric field. The main advantages of this filter are its very low power consumption and its versatility of passband programming by virtue of separately addressable voltages under microprocessor control. Two experimental embodiments of the filter are described, one using longitudinal fields, collinear with the light beam, the other using transverse fields in a "thick waveguide" configuration. Experimental results of filter characteristics in the wavelength range2-10 mum are presented. We also present examples of passband synthesis that are achieved by apodizing the amplitude of the applied electric field perturbations. These include passband broadening and sidelobe suppression. The experimental transfer characteristics exhibit good agreement with the theoretical computer plots. Typical driver voltages are ∼ 500 V.     

Laser detection utilizing tunable acoustooptic filters

A laser detection technique was developed utilizing frequency modulated tunable acoustooptic filters. CW laser radiation measuring about5(10^{-7})mW was detected in the presence of an incoherent background irradiance of 0.1 W/cm².     

脉冲功率电容器的应用和发展

介绍了国内外脉冲功率电容器的应用和研制现状,重点介绍了高储能密度电容器介质材料和脉冲功率电容器的性能参数,指出了今后需要解决的主要问题,总结了脉冲功率电容器的发展趋势,提出了发展我国脉冲功率电容器的建议。     

Electronically tunable ring resonator microstrip and suspended-substrate filters

Electronically tunable ring resonator microstrip and suspended substrate microwave filters with high tuning speed are presented. The filters are realised using two coupled ring resonators with GaAs varactors as the tuning elements. Computer optimised circuits are used at the input and the output to obtain better than 10 dB return loss across the tuning band. Tuning ranges of 1.075-2.25 GHz for the microstrip filter and 1.35-2.075 GHz for the narrower suspended substrate filter are predicted by computer simulation.<>     

Integrated acoustooptic tunable filters using weighted coupling

A detailed theory and experimental results are presented on weighted-coupling integrated acoustooptic tunable filters (IAOTF). A low-sidelobe-level single-stage IAOTF in which the weighted coupling was facilitated by focused surface acoustic waves along an interaction length of 6.0 mm has been realized on a Y-X LiNbO₃ substrate, 8 mm in length. The measured performances of this weighted-coupling IAOTF at the optical center wavelength of 1.31 μm include a peak mode conversion at the acoustic center frequency of 214.6 MHz, a wavelength tuning range of 110 nm, a -3 dB optical bandwidth of 4.1 nm, and a switching rise time of 0.965 μs. Sidelobe levels below -21.4 dB have been accomplished at the mode-conversion efficiency of 15 percent and an RF drive power of 160 mW     

All-optical tunable filters built with discontinuity-assisted ringresonators

Numerically simulated performance is presented in a new type of bandstop and bandpass filters, built with discontinuity-assisted ring resonator (DARR)-loaded couplers. The operating characteristic of the bandpass filter is similar to that of a long grating with a centered cavity or a photonic crystal with a defect. The filters are tuned by varying the refractive index or the length of the waveguide forming the ring or the cavity. Selectivity and tuning range are controlled by the coupling coefficient of the couplers, by the order of resonance in the rings, and by the reflection coefficient of the discontinuities. A design procedure and the effect of loss are also presented