提取超声换能器特征信号的自适应滤波器的设计

叙述了用开关电容滤波器LMF100构成二阶带通自适应滤波器的设计。其带通滤波器中心频率将跟随特征信号频率变化,克服了传统滤波器带通中心频率不易改变的缺点。     

浅探谐波滤波器原理与维护

谐波滤波器是DF100A短波发射机的重要组成部分,在使用的过程中常常会出现各种设备故障,如果不能很好的处理和预防,将会严重影响安全播音.本文着重阐述DF100A短波发射机谐波滤波器的原理和维护. 1 谐波滤波器的滤波器的选择 滤波器是用来选择频率的电路,即让某些频率通过同时阻止其他频率信号的通过.滤波器有多种形式:低通、高通、带通、带阻. 低通滤波器同规格所有低于截止频率-3dB的频率,这种滤波器用于除去高于至二级频率的信号谐波成分和干扰信号. 高通滤波器通过所有高于截止频率-3dB的频率,这种滤波器用于消除低于截止频率的强信号干扰.     

有源带通滤波器的设计

有源带通滤波器以其良好的幅频特性,在信号的分析与测量中得到广泛应用。根据标准有源带通滤波器原理,采用频域分析法,可得出有源带通滤波器的特征频率计算公式。在此基础上,推荐了一种快捷实用的参数选择方法,并对单级、两级串联有源带通滤波器进行了幅频特性数字仿真。     

全相位偶对称频率采样法设计FIR滤波器

提出FIR滤波器全相位偶对称频率采样设计方法,此方法可以根据截止频率的要求设置移位因子,将两个子滤波器分别进行相反方向的移位,并构造补偿滤波器,最后将子滤波器和补偿滤波器组合而成所需的低通、高通、带通、陷波等滤波器,这种设计方法概念明确,简单易行,解决了传统FIR滤波器设计方法不能精确控制截止频率的难题.     

多用途有源滤波器UAF42的应用

论述了Ｂｕｒ－Ｂｒｏｗｎ公司９０年代设计生产的多用途通用有源滤波器ＵＡＦ４２集成芯片的主要功能、性能及使用方法。给出了低通、高通、带通和带阻有源滤波器的设计公式、电路和对５０Ｈｚ陷波器的设计实例。     

基于FPGA的可编程滤波器的设计

应变测试系统中传感器输出信号非常微弱,传感器与测量仪连接线较长容易引入干扰信号,且应变仪应用场地干扰信号不同。介绍了一种用FPGA实现的可编程IIR型滤波器,该滤波器以二阶基本节为核心,通过改变二阶基本节的系数来改变滤波器滤波模型及截止频率。嵌入式计算机把系数写入滤波器实现低通、高通、带通及带阻滤波。该滤波器在应变测量仪器应用上取得了很好效果。     

用MAX274/275实现切比雪夫有源带通滤波器

介绍了用ＭＡＸＩＭ公司的连续时间滤波器ＭＡＸ２７４／２７５实现切比雪夫（Ｃｈｅｂｙ－ｓｈｅｖ）有源带通滤波器的设计方法，并给出一个切比雪夫有源带通滤波器的实例。     

单片机的可控放大器程控滤波器设计

基于单片机设计了一种可控放大器程控滤波器.可控放大部分以可控放大器PGA203为核心,实现输出增益的动态调整;程控滤波器以开关电容滤波器LMF100为核心,使用DDS芯片AD9850产生可变的时钟,实现滤波器的截止频率可调;幅频特性测试仪采用AD9850产生扫频信号,AD837进行有效值检测,TLC5510进行A/D转...     

一种线性集成电路RC有源滤波器

有源滤波器已在航空、通讯、电子仪器等许多领域得到广泛应用。由于半导体技术的新成就,特别是线性集成电路的问世,为有源滤波器的更加小型化和性能的进一步提高提供了新的可能性。现在,有源滤波器的研究和应用越来越被人们所重视。本文介绍的是为新研制的多通道振动测量仪设计的一种RC有源滤波器。由于采用线性集成电路作为有源元件并成功地引入了适当的反馈,该滤波器与具有相同滤波性能其它滤波器相比,电路简单,而且大大放宽了对滤波器无源元件的一致性的要求,调整也方便。具有这种RC有源滤波器的振动测量仪能提高测量精度使测量结果更加可靠和稳定。文中简述了RC有源低通、高通和带通滤波器的电路结构设计、电路元件的选择与计算以及性能调试方法。给出了用于振动测量仪的RC有源带通滤波器的性能数据及其典型特性曲线。     

C8051F020单片机的程控滤波器设计

本文设计了一个二阶程控滤波器。放大器增益可设置：低通、高通滤波器截止频率等参数可设置。     

A compact reconfigurable bandpass/lowpass filter with independent transmission zeros based on generalized NRI metamaterial

This article introduces a new design and analysis of a compact reconfigurable bandpass/lowpass filter based on compact negative refractive index metamaterial transmission line. The filter equivalent circuit has been designed as a cascade of three cells of bisected‐Π/Π configuration. The reconfigurable function was achieved using inserted switches in ON and OFF modes within the cells. The filter works as bandpass when all switches are in ON condition and for lowpass switch‐1 is in OFF and switch‐2 in ON condition. The low pass filter has 3‐dB cutoff frequency of 3.25 GHz with a selectivity of 170 dB/GHz. The bandpass filter is cantered at 3.65 GHz and has a well‐matched pass band with insertion loss of 0.2 dB and wide stop band with two transmission zeros (TZs). The frequency positions of TZs are independently varying with series and shunt loading elements. The filter performance has been validated through circuit model, electromagnetic simulation, and experimental measurements. The electrical size of bandpass filter excluding feed line is 0.22 λ_g × 0.20 λ_g (12 × 11 mm²) at center frequency of 3.65 GHz and for lowpass filter is 0.19 λ_g × 0.18 λ_g at cutoff frequency of 3.25 GHz. The filter can be applied in suitable for different wireless applications.     

Novel configuration of ultra‐wide band uni‐planar configuration of complementary split ring resonator composite right/left‐handed based band pass filter with sharp roll off and good stopband attenuation

In this paper, a compact novel simple design of ultra‐wide bandpass filter with high out of band attenuation is presented. The filter configuration is based on combining an ultra‐wide band composite right/left‐handed (CRLH) band pass filter (BPF) with simple uni‐planar configuration of complementary split ring resonator (UP‐CSRR). By integrating two UP‐CSRR cells, the ultra‐wideband CRLH filter roll‐off and wide stopband attenuation are enhanced. The filter has 3 dB cutoff frequencies at 3.1 GHz and 10.6 GHz with insertion loss equals 0.7 dB in average and minimum and maximum values of 0.48 dB and 1.05 dB, respectively over the filter passband. Within the passband. The transition band attenuation from 3 dB to 20 dB is achieved within the frequency band 1.9 GHz to 3.1 GHz (48%) at lower cutoff and the frequency band 10.6 GHz to 11.4 GHz (7%) at upper stopband. Moreover, the filter has a wide stopband attenuation >20 dB in frequencies 11 GHz to 13.6 GHz (21%) and ends with 3 dB cutoff frequency at 14.8 GHz. Furthermore, the designed filter size is very compact (23 × 12 mm²) whose length is only about 0.17 λ_g at 6.85 GHz. The filter performance is examined using circuit modeling, full‐wave simulations, and experimental measurements with good matching between all of them.     

Design and fabrication of a compact microstrip lowpass‐bandpass diplexer with high isolation for telecommunication applications

This study aimed to design and fabricate a lowpass‐bandpass (LP‐BP) diplexer with high isolation for telecommunication applications including wireless communications. The results revealed that the ?3 dB cutoff frequency of the lowpass filter (LPF) was equal to 0.82 GHz. The advantages of the LPF section include a very high suppression factor (SF) parameter (about 4.4), very sharp roll‐off‐rate (ROF or ζ) parameter (687), and a very high figure of merit (FOM) (about 233491). The bandpass filter (BPF) section was designed applying dual‐mode resonators with triband. The central frequencies of these tribands were equal to 2.38, 3.93, and 5.65 GHz. In the following, an SMV‐1247‐079LF SMD varactor diode is used to adjust the proposed LPF. The tuning range for the proposed LPF is 0.3‐0.72 GHz. In the proposed diplexer, the isolation between the output ports was higher than 45 dB. The results of measurements were in good agreement with those of the simulation.     

抽头式交指带通滤波器的优化方法研究及仿真

研究滤波器超低频噪声的过滤优化问题。针对数字信号中混有大量超低频噪声的情况下,传统的等效电路过滤方法无法准确控制输入输出公差精度,控制阀值存在较大波动,造成过滤效果不理想。为了解决上述问题,提出了一种抽头式交指带通滤波算法,利用两终端的外部品质因数Q和谐振器间的耦合系数K设计抽头式交指型带通滤波算法,运用迭代分频滤波方法,高精度的过滤超低频高斯噪声。克服传统方法依赖阀值的弊端。仿真结果表明,抽头式方法能较好的过滤超低频高斯噪声,取得了满意的结果。     

Wide stopband single layer quasi-elliptic ultra-wideband bandpass filter

This article presents the design of a microstrip ultra-wideband (UWB) bandpass filter that exhibits desirable characteristics of low-loss, high selectivity, wide stopband and high out-of-band rejection at room temperature. These characteristics are normally achieved with high temperature superconductor filters that require cryogenic cooling. The design of the proposed filter was realized by exciting multiple resonant modes in a unique Z-shaped microstrip resonator. The admittance of the filter configuration can be tuned prior to fabrication to adjust its center frequency by about 11.5% without affecting the profile of the bandpass response however this can have an impact of the loss. The proposed configuration allows adjustment of the upper and lower transmission zeros defining the bandpass response by 20.5% and 11.4%, respectively, without degrading the overall filter response. The low-loss quasi-elliptic function UWB bandpass filter design was fabricated on a commercially available dielectric substrate using standard PCB technology and its performance verified. The fabricated filter exhibits insertion-loss of 0.68 dB and return-loss better than 17 dB.     

A bandpass filter with adjustable bandwidth and predictable transmission zeros

In this article, a microstrip bandpass filter with an adjustable bandwidth and predictable transmission zeros is proposed. The proposed filter is implemented by combining two hairpin edge‐coupled resonators with interdigital capacitors. Compared to typical edge‐coupled filters, the proposed filter provides a wider bandwidth resulting from a higher coupling strength between its resonators. To further increase the coupling and consequently the bandwidth, a pair of etched slots in the ground plane is used. By adjusting the geometrical parameters of the interdigital capacitors and etched slots, the bandwidth can be easily adjusted. The filter features two transmission zeros, which are determined by means of the semi‐analytical model developed as part of this work. Furthermore, the proposed filters can be cascaded to obtain a sharper cutoff frequency response. Frequency responses of the filters from measurements are in good agreement with those simulated using IE3D in the 5–9 GHz range. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

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。     

A widely tunable bandpass filter adopting novel fully tunable resonators

A widely tunable bandpass filter adopting a novel fully tunable resonator is proposed in this letter. The fully tunable resonator is mainly consisted of an open ring, a frequency tuning structure, and a coupling tuning structure. Adopting the fully resonators, the center frequency, the input/output external Q value, and the coupling coefficients can be tuned at the same time. And the tuning range of a tunable filter adopting the novel fully tunable resonators can be expanded. The fully tunable resonators can be combined to achieve more excellent suppression performance. A widely tunable bandpass filter consisted of five fully tunable resonators with 86.5% frequency tuning range is designed, fabricated, and measured. The simulated results are in good agreement with the measured ones.     

基于频谱分析信号处理的涡街流量计设计

给出了一种基于频谱分析信号处理的涡街流量计的设计,分析了采用频谱分析信号处理与带通滤波相结合的去噪方法。硬件上分析了核心控制器件MSP430F5438、压电传感器信号的放大与低通滤波、多通道的可选带通滤波器、程控放大及峰值检测模块、信号的整形输入,软件上分析了频率估算、FFT算法实现、峰值检测与放大、带通选择、频率计数,最后,在气体标准装置上进行了检定验证。结果表明,该流量计采用频谱分析信号处理和带通滤波,大大提高了液体流量测量的精度和抗干扰性。     

具有镜频抑制功能的可重构上变频器设计

介绍了一种带镜频抑制的可重构上变频器。它由FET混频器、压控振荡器(VCO)、低通滤波器及可调带通滤波器组合而成。这种上变频器能够将给定的中频信号变换成在一个宽的频率范围内期望的任意频率的射频信号,并保持高的镜频抑制水平。随着VCO输出频率的变化,镜频、本振和谐波频率同样发生变化并有可能产生混叠。