Design of Bessel low-pass filter using DGS for RF/microwave applications

A synthesis method to design a defected ground structures (DGS)-based Bessel low-pass filter (LPF) using a triangular and an open-square (OS)-type DGS is reported. For the five-pole Bessel LPF at f_c = 2.5 GHz, we get 10.6 dB/GHz selectivity using the triangular DGS; while the OS-type DGS provides 39 dB/GHz selectivity. For these two filters, the 10 dB impedance matching BW is 76% and 84%, respectively. It is a much wider BW that is obtained for a lumped element Bessel LPF. The maximum group delay (GD) variation within the pass band is 25pS and 28pS, respectively. The 20 dB rejection BW can be increased from 5.8 GHz to 18.8 GHz with increase in the order of filter from 5 to 11. We have also presented the design of a compact five-pole DGS-based elliptic filter with selectivity 38.2 dB/GHz and 17.8 dB return loss. Results on the DGS-based elliptic filter, Butterworth and Chebyshev filters are also presented. The experimental results are compared against the recently reported LPFs. Our reported filters perform better with respect to selectivity and group delay variation. The flatter GD and high selectivity, along with a wide 10 dB impedance matching BW, make the DGS Bessel filter a candidate for high-speed data communication, front end of a wideband communication system and efficiency improvement of a power amplifier.     

基于分形技术的阶跃阻抗微带低通滤波器设计

设计阶跃阻抗微带低通滤波器时,由于阶跃阻抗微带线结构的不连续性,会导致版图仿真与电路原理图仿真结果相差很远。为了解决这一问题,提出先对阶跃阻抗微带线的结构参数进行预处理,然后引入分形技术对低阻抗微带线的版图结构作进一步优化的设计方法,利用分形结构成阶梯锯齿状分布的线宽来改善滤波器的通带特性,而又几乎不影响滤波器的阻带特性,获得了满意的滤波性能;以一个5阶契比雪夫型阶跃阻抗微带低通滤波器设计为例,仿真结果表明:滤波器通带内的最大反射损耗从-0.87 dB降低到-15.22 dB。与直接采用分形结构的设计方法相比,该方法有利于减少分形结构的迭代次数,降低加工精度要求,从而降低制作成本。     

基于Hilbert分形缺陷地结构的微带低通滤波器

采用Hilbert分形缺陷地结构单元和并联枝节串联设计制作了一种微带低通滤波器。HFSS仿真结果表明:设计的滤波器通带回波损耗小于–20 dB,通带范围为0~5 GHz,阻带带宽能达到10 GHz以上。实物测量结果与仿真结果基本吻合。实现了回波损耗和通带内的纹波小、过渡带陡峭、阻带宽、结构紧凑、尺寸小的微带低通滤波器。     

开关电容低通滤波器的设计

为了滤除信号中掺杂的高频噪声,设计一种六阶级联式开关电容低通滤波器,以数据采样技术代替传统有源RC滤波器中的大电阻,有利于电路的大规模集成。滤波器由双二阶子电路级联而成,电路中的电容值利用动态定标技术计算确定。用Hspice进行仿真验证,结果表明:开关电容低通滤波器能较好地对信号进行整形,其频率特性符合设计指标。     

基于DDS的椭圆函数低通滤波器的设计

低通滤波器是直接数字频率合成DDS的重要组成部分,其性能的好坏直接影响整个DDS的特性.提出一种基于DDS的椭圆函数低通滤波器的设计方案,该设计采用全新的归一化方法,并使用EDA软件Multisim2001进行仿真,确定了滤波器的结构,阶数,以及设里了相关参数,从而设计出截止频率为160MH:的7阶椭圆函数滤波器.该低通滤波器幅频特性良好,具有快速的衰减性.因此该设计方案可适用于不同频段、阶数、类型的滤波器设计.     

电压模式n阶CCII+低通滤波器的设计

提出了一种仅仅用第二代电流传送器(CCII+)实现的高阶电压模式低通滤波器,推导了系统的设计公式。设计了六阶Butterworth低通滤波器,并用PSPICE进行仿真分析。设计和仿真结果表明,该低通滤波器电路设计正确,电路结构简单,所用的元器件数目较少。     

基于C型DGS的双通带滤波器设计

基于环形谐振器的基础结构,提出了新型C型缺陷地结构(defected ground structure,DGS)的双通带滤波器。利用C型DGS结构的高阻抗传输线特性,通过调节C型DGS结构的长度与宽度尺寸,可以实现对双频段带通滤波器的工作频段控制。最后给出了一个2.4 GHz和3.45 GHz工作频段的微带双通带滤波器设计实例,其测试结果与仿真结果吻合。     

Design of high-temperature superconducting low-pass filter forbroad-band harmonic rejection

A new type of low-pass filter based on a coupled line and transmission line theory is proposed for suppressing harmonics and spurious frequency. The seventh-order coupled-line low-pass filter with strip line configuration was fabricated using a high-temperature superconducting (HTS) thin film on MgO(100) substrate. The seventh-order low-pass filter has five attenuation poles in the stop band. Its cutoff frequency is 1 GHz with a 0.01-dB ripple level. The fabricated filter exhibits a characteristic stop band in the range from 1 to 7 GHz. A measured insertion loss at the pass-band of the HTS low-pass filter is 0.2 dB at 77 K, while the maximum return loss is 17.1 dB. These results match well with those obtained by the EM simulation. The new low-pass filter structure is shown to have attractive properties such as compact size, wide stop band range, and low insertion loss     

模拟跨阻低通滤波器的设计

跨阻滤波器的输入为电流信号,输出为电压信号.本文给出了跨阻滤波器的设计方法,并按照品质因数Q的低、中、高详细介绍了三种双二阶节跨阻低通滤波器的电路拓扑结构及其参数计算方法.二阶跨阻低通滤波器与传统滤波器相级联即可实现高阶跨阻低通滤波器.最后,通过高阶跨阻低通滤波器的设计实例,验证文中所给出的设计方法的有效性.     

Compact microstrip low-pass filter with sharp rejection

This letter presents a compact multisection sharp-rejection microstrip low-pass filter. Each section consists of a microstrip line section and an interdigital capacitor. The analysis for optimizing the attenuation poles by adjusting the finger number, and the width and length of the microstrip line section, is presented. The cascaded four-section low-pass filter has a return loss of better than 17 dB and an insertion loss of less than 0.7 dB from DC to 1.6 GHz. The rejection is better than 20 dB from 2.1 to 7.5 GHz.     

A low-pass filter with extremely low sensitivity

An active RC low-pass network with very low sensitivity is presented. It uses two finite-gain voltage amplifiers and is capable of realizing highly selective functions.     

小型化超宽阻带共面波导低通滤波器设计

为了解决传统CPW低通滤波器尺寸偏大、阻带较窄和插入损耗偏大的问题,采用 /4阶梯阻抗谐振单元（SIR）加载半圆形并联枝节（SISS）和缺陷地结构（DGS）单元的紧凑型结构设计了一个5阶CPW低通滤波器,分析了各单元结构参数对阻带性能的影响,引入微带线补偿方法对共面波导中心导体线特性阻抗进行局部补偿,改善了阻抗匹配性能,进一步降低了通带内的回波损耗和插入损耗。测试结果表明：该滤波器结构尺寸25mm×18mm,3dB截止频率3.5GHz,阻带范围3.8～17GHz。实现了CPW低通滤波器的低插入损耗、超宽阻带和小型化。     

小型化宽阻带LTCC微波低通滤波器的设计与研制

先根据滤波器衰减量要求,理论分析确定滤波器的阶数及电路原理图,再用ADS软件优化仿真获得电路元件初始值,然后采用微波电磁场仿真软件HFSS对滤波器物理模型优化仿真,成功设计了一款3 d B截止频率为1 750 MHz、宽阻带频率2 035~6 700 MHz范围内衰减量大于20 dB的LTCC微波低通滤波器,并采用LTCC工艺制备该微波低通滤波器,尺寸为3.2 mm×1.6 mm×0.9 mm。制备样品实测结果与仿真吻合,说明采用该方法设计、研制小型化宽阻带LTCC微波低通滤波器是可行的。     

A novel cross-shape DGS applied to design ultra-wide stopband low-pass filters

This letter presents a novel low-pass filter with an ultra-wide stopband. The proposed filter is comprised of a new cross-shape defected ground structure (CSDGS). By using this structure, the filter not only supports conventional DGS performances with a sharp rejection, but also exhibits an ultra-wide stopband. For the deigned low-pass filter, an insertion loss of less than 2dB from dc to 3.5GHz and the rejection is better than 20dB from 4.3 to 15.8GHz. Predicted performances show widened and deepened stopband beyond the low passband. Furthermore, it is confirmed by measurement.     

A modified low-pass filter with progressively diminishing ripples

A modified low-pass filter functions are proposed. A modified inverse Chebyshev function possesses progressively diminishing ripples in the stopband whereas the modified Chebyshev function exhibits ripples diminishing toward = 0 in the passband.Both are realizable in the doubly-terminated ladder structures for the ordern even or odd, thus lending themselves amenable to high-quality activeRC or switched capacitor filters through the simulation techniques.     

基于平衡技术的微带低通滤波器版图优化设计

微带线结构的不连续性,使反射损耗和插入损耗较大,影响滤波器性能。利用平衡法提升滤波器并联分支中较低的特性阻抗,达到降低微带线宽度的目的,从而均衡整个滤波器的宽度,使版图仿真优化。以一个5阶切比雪夫微带低通滤波器设计为例,仿真结果表明,滤波器通带内反射损耗从-9.566dB降低到-15.837dB,插入损耗从0.679dB降低到0.322dB,与直接采用Richards变换和Kuroda规则设计微带低通滤波器相比,该方法能缩短滤波器设计周期,获得满意的滤波器性能。     

Design and implementation of a low-pass filter for microsensor signal processing

A novel low-pass filter that consists of a switched capacitor filter(SCF) and its antialiasing prefilter and smoothing postfilter is proposed for a microsensor signal processing system,which is used in separation point detection on the surface of micro air vehicles.In the system,the filter is not only applied to finish the function of filtering but also used as the front end antialiasing filter of the over sampling analog-to-digital converter.This proposed implementation mostly relies on the design of a ...     

应用于微传感器信号处理系统的低通滤波器的设计与实现

研究旨在设计一款应用于微型飞行器机翼表面分离点检测的高精度微型传感器信号处理系统中的模拟低通滤波器。该滤波器由开关电容滤波器及其前置抗混叠滤波器和后置平滑滤波器组成。在整个信号处理系统中,滤波器不仅起到滤除信号干扰和噪声的作用,而且还用作过采样模数转换器的前置抗混叠滤波器。设计基于无锡上华0.5um 2层多晶硅3层金属（2P3M）CMOS 工艺,在3.3V电源电压下,采用相关双采样技术（CDS）及优化的开关组合,削弱了器件非理想特性的影响,提高了开关电容滤波器的精度,并运用具有低元件灵敏度及失真特性的多重反馈型二阶低通滤波器作为抗混叠滤波器和平滑滤波器,保证了整个滤波器具有良好的高频衰减特性。芯片测试结果表明：该芯片的截止频率为0.7kHz, 面积为0.39 mm2,功耗仅为1.53mW。     

Integrated switched-capacitor low-pass filter with combined anti-aliasing decimation filter for low frequencies

A new combined antialiasing decimation filter is presented which allows the implementation of a low-frequency switched-capacitor filter on a single chip. Experimental results are presented for a CMOS second-order low-pass filter with 1 dB passband ripple, a cutoff frequency of 2 Hz, and a dynamic range of 84 dB. The decimation filter converts the input clock of 16 kHz into an output clock of 250 Hz. The integrated anti-aliasing filter has a low pole frequency of about 3 kHz.     

Small but long Koch fractal monopole

A small but long wire fractal antenna based on the Koch curve is presented. Experimental and numerical results show that the antenna improves the features of a common linear monopole. The radiation resistance is increased and the Q is reduced at each fractal iteration, approaching the fundamental limit on small antennas