Design of Novel Ultra-Wideband Bandpass Filter with High Selectivity and Wide Stop Band and Optimizing it with Neuro-Genetic Method

This paper develops a novel ultra-wideband bandpass filter with high selectivity, deep stop band and compact size. By linking a broadband bandstop filter at two sides with two feed lines via interdigital coupled lines with enhanced coupling degree, an initial ultra-wideband bandpass filter is created. In this filter, all undesired pass bands are rejected by broadband bandstop filter embedded in middle of ultra-wideband filter. Then, stepped impedance open stubs are used for realizing transmission zeros in pass band edges to increase selectivity. Finally, a neuro-genetic method is applied for optimizing of proposed ultra-wideband bandpass filter. For this task, first a nonlinear relation is established between the input (layout parameters) and output (electrical responses) data by using neural network. Then, genetic algorithm is used in conjunction with neural network model for optimizing the ultra-wideband bandpass filter parameters. The designed filter was fabricated and measured that showed good characteristics including deep stop band and very high pass band selectivity.     

UWB Bandpass Filter Using Microstrip-to-CPW Transition With Broadband Balun

A novel ultra-wideband bandpass filter (BPF) is presented using a back-to-back microstrip-to-coplanar waveguide (CPW) transition employed as the broadband balun structure in this letter. The proposed BPF is based on the electromagnetic coupling between open-circuited microstrip line and short-circuited CPW. The equivalent circuit of half of the filter is used to calculate the input impedance. The broadband microstip-to-CPW transition is designed at the center frequency of 6.85 GHz. The simulated and measured results are shown in this letter.     

The Digital Elliptic Filter--A Compact Sharp-Cutoff Design for Wide Bandstop or Bandpass Requirements

Detailed design procedures are presented for a practical elliptic-function filter form capable of achieving high selectivity in a very compact configuration. This filter form, called the digital elliptic because of its digital construction and elliptic function response, can provide either bandpass or bandstop characteristics. Examples are given to illustrate typical design procedures for both bandpass and bandstop applications. Experimental results are presented for an octave bandstop design.     

Pulse shaper for ultra-wideband applications

The impulse-radio-based ultra-wideband system, which transmits and receives baseband pulses directly without a carrier, is very attractive for wireless sensor networks. It features very simple architecture and low power consumption [1]. In such a system, subnanosecond impulses are used not only for transmitting the data streams but also for downsampling the received pulses in the receiver. To realise high performance impulse generators, various circuit schemes have been proposed in the literature [2?4]. In addition, because of the coexistence of the UWB and WLAN radios at the frequency band of 5?6 GHz, in a recent ultra-wideband design an additional bandstop filter is urgently required to alleviate the potential interference. In [4], a higher-order derivative Gaussian pulse generator with band-notched characteristics at the WLAN band is proposed by utilising two microstrip bandpass filters. In this Letter, we propose a new ultra-wideband pulse shaper which demonstrates comparable performance but more compact size. The pulse shaper is composed of two parts: a thirdorder bandstop filter (BSF) and a third-derivative Gaussian pulse generator. The bandstop filter is realised by incorporating a new meandered V-sickle slotted ground structure. The experimental results reveal that the new design not only complies with the FCC emission mask but demonstrates excellent signal suppression at the 5 GHz WLAN band. It also occupies a smaller circuit area compared to that in the previous work [4].     

新型毫米波微带带通滤波器

介绍了一种新型的加载电容型毫米波微带带通滤波器。对这种滤波器进行了分析,推导出了滤波器中所用谐振单元间的耦合系数。该滤波器通过加载电容而出现慢波效应,使得在不改变电路性能的情况下,减小了电路尺寸。同时由于电路中加载电容形成的慢波效应而出现了带阻效应,因此对谐波有很好的抑制作用。利用高频分析软件CST仿真分析并设计了这种新型的加载电容型毫米波微带带通滤波器,实验结果与设计曲线结果相符。     

Compact Ultra-Wideband Bandpass Filters Using Composite Microstrip–Coplanar-Waveguide Structure

Compact ultra-wideband bandpass filters are proposed based on the composite microstrip–coplanar-waveguide (CPW) structure. In this study, the microstrip–CPW transitions and the CPW shorted stubs are adopted as quasi-lumped-circuit elements for realizing a three-pole high-pass filter prototype. By introducing a cross-coupled capacitance between input and output ports of this high-pass filter and suitably designing the transition stretch stubs, a compact three-pole ultra-wideband bandpass filter is implemented with two transmission zeros located close to the passband edges. To further improve the selectivity, two microstrip shorted stubs are added to implement a five-pole ultra-wideband bandpass filter with good out-of-band response. Being developed from the quasi-lumped elements, and not from the transmission lines, the proposed ultra-wideband filters have sizes more compact than those of the published wideband filters. The proposed ultra-wideband filters have the merits of compact size, flat group delay, good insertion/return loss, and good selectivity. Agreement between simulated and measured responses of these filters is demonstrated.     

Distortion Mechanisms in Varactor Diode-Tuned Microwave Filters

This paper examines the broadband distortion behavior in flexible filters employing varactor-diode tuning elements. Series- and parallel-resonant varactor-loaded transmission-lines, both commonly used in bandpass and bandstop microwave filters, are analyzed. Nonlinear Volterra-series analysis is employed to determine the second- and third-order distortion ratios dependent on the frequencies of the incident signals. It is shown that in a bandpass filter (employing parallel tuned resonators), maximum distortion occurs in the passband, while in a bandstop filter (employing series tuned resonators), minimum distortion occurs at the minimum-loss passband. The analysis is verified by practical measurement of filters employing the two modes of resonators.     

Modeling and Optimization of Compact Microwave Bandpass Filters

This paper presents the modeling and optimization of compact microwave bandpass filters whose compactness leads to complex and strong stray coupling paths, thereby making the identification of a simple and sparse coupling topology difficult and even impossible. The strong coupling coefficients needed for a broadband response can also cause an ambiguity in identifying the spatial extent of local resonances. An equivalent circuit, which is extracted directly from Maxwell's equations, is used in optimizing these filters. The filter is represented by its global resonances instead of individual resonators. The extraction of the parameters of the equivalent circuit is carried out in the physical frequency and not in the normalized frequency in order to preserve the physicality of the equivalent circuit, especially for asymmetric responses. The technique is successfully applied to the optimization of second-order suspended stripline bandpass filters with one transmission zero either below or above the passband, as well as fourth-order filters with three transmission zeros. A fourth-order filter with three transmission zeros is fabricated and measured.     

宽阻带超宽带带通滤波器的设计

提出了一种新型结构的超宽带带通滤波器。这种滤波器结构基于最优的短路支节传输线滤波器,短路支节之间的连接线替换成一种层叠结构的阶跃阻抗发夹线。阶跃阻抗发夹线谐振器的低通滤波性能较好地实现了滤波器的阻带衰减,而对滤波器的通带传输特性影响小。由于阶跃阻抗发夹线的慢波特性,滤波器的尺寸在长度上缩减了23%,其结构更加紧凑。     

基于双二阶的低功耗椭圆带通滤波器设计

为解决椭圆滤波器通带纹波较大的问题,设计了一种基于双二阶的椭圆窄带带通滤波器,滤波器由3个双二阶构造的带阻滤波器级联实现,滤波器中心频率11kHz,带宽2kHz,通带纹波不超过1dB,阻带衰减不小于30dB每倍频程。滤波器功耗不超过30mW,满足水下引信接收机长时间工作的要求。     

Switchable Embedded Notch Structure for UWB Bandpass Filter

A reconfigurable ultra-wideband (UWB) bandpass filter (BPF) with switchable notch for UWB system is presented. The UWB BPF is embedded with two identical switchable notch structures, in which PIN diodes are used for electronic switching. A bias circuit for UWB applications was investigated and designed to control the state of PIN diodes in order to activate or deactivate the notch without an affect on the response of the BPF. A demonstrator for this type of switchable notch UWB filter is designed and fabricated. Simulated and measured results are described.      

A Dual-Band Filter Realized by Alternately Connecting the Main Transmission-Line With Shunt Stubs and Shunt Serial Resonators

In this letter, we present a novel network for dual-band filter, the circuit of which is a mixture of shunt stub bandpass filter and shunt serial resonator bandstop filter. The stopband of the bandstop filter will split the passband of the bandpass filter and result in a dual-band response. The simulated and measured results are given. This kind of filter has the advantage of bigger and controllable bandwidths and lower insertion loss compared with traditional SIR dual-band filters.      

新型紧凑型带通滤波器的设计

文章设计了两个通带位于超宽带低频范围的带通滤波器,用一种T型结构来代替传统带通滤波器中的四分之一波长传输线,这种替代减小了滤波器的尺寸.而且,可以很方便的控制位于滤波器通带两端的传输零点,即合理的调节开路支线的电长度,进而可以方便的控制滤波器的通带范围.为了证明以上新型滤波器的优点,设计了两个开路支线电长度不同的带通滤...     

基于LTCC技术的带通滤波器分析与设计

文章介绍了一种中心频率为2.45GHz的LTCC多层带通滤波器的设计方法。利用二阶耦合谐振带通滤波器的原型,通过一种分析合成带通滤波器的方法,将原型电路等效为4个L型匹配电路,设定其中两个匹配品质因子,经过推导并进行参数值取舍后,即可得到原型电路中所有元件的合成公式以及电路中各器件的参数值。利用三维电磁场仿真软件HFSS建立模型,可以将电磁模拟结果与电路仿真结果较好地吻合。最后采用标准LTCC工艺实现出尺寸为3.6mm×2.9mm×1.1mm的带通滤波器。     

EBG-Embedded Multiple-Mode Resonator for UWB Bandpass Filter With Improved Upper-Stopband Performance

An electromagnetic bandgap (EBG) embedded multiple-mode resonator (MMR) is proposed to constitute an upper-stopband-improved and size-miniaturized ultra-wideband (UWB) bandpass filter (BPF). This EBG-embedded MMR is studied to relocate its first three resonant modes within the 3.1-10.6GHz passband, whereas placing its 4th resonant mode at the coupling transmission zero of interdigital coupled-lines that drive this MMR at two sides. Meanwhile, the fifth resonant mode is rejected by virtue of the bandstop behavior of the EBG itself. Thus, a modified UWB BPF with widened upper-stopband, sharpened upper rejection skirt and lowered loss in the passband is finally constituted, designed and fabricated. The measured results demonstrate that the insertion loss is lower than 1.0 dB in the passband (4.0-10.6GHz) and higher than 15.0dB in the upper-stopband (12.0 to 20.0GHz) while the group delay variation in the passband is less than 0.2ns     

Quarter-Wavelength Coupled Variable Bandstop and Bandpass Filters Using Varactor Modes

A quarter-wavelength coupled bandstop filter rising varactor diodes for the 6-GHz band has been proposed and tested. Frequency giving maximum attenuation varies from 4.4 GHz-7 GHz. A quarter-wavelength coupled variable bandpass filter using varactor diodes for the 4-GHz band is also proposed and tested. The passband width varies from 730 MHz-1.22 GHz. The center frequency of the filter can also be changed.     

Dual-band bandpass filters using equal-length coupled-serial-shunted lines and Z-transform technique

A synthesizing method is presented to design and implement digital dual-band filters in the microwave frequency range. A dual-band filter consists of a bandstop filter and a wide-band bandpass filter in a cascade connection, wherein the transfer functions of both the bandpass filter and bandstop filter are expressed in the Z domain. The bandstop filter is implemented by using a coupled-serial-shunted line structure, while the wide-band bandpass filter is constructed by using a serial-shunted line configuration. In particular, the bandwidth of each passband of the dual-band filter is controllable by adjusting the characteristics of both the bandpass filter and bandstop filter. By neglecting the dispersion effect between microstrip lines of different widths over a wide bandwidth, a dual-band filter is realized in the form of microstrip lines and its frequency responses are measured to validate this method.     

宽阻带阶跃阻抗发夹线带通滤波器设计

提出了新的抑制微带带通滤波器寄生通带的方法。这种方法通过级联阶跃阻抗发夹线谐振器构成的椭圆函数低通滤波器于带通滤波器的输入/输出端,显著改善了后者的阻带抑制特性。本文基于新的等效电路模型,推导出了此类低通滤波器的阻带传输零点位置。设计了L波段宽阻带阶跃阻抗发夹线带通滤波器验证了理论分析和设计过程的正确性。     

一种具有陷波特性的超宽带带通滤波器

采用修改的多模谐振器(MMR)结构,在输入端与输出端开槽形成交叉耦合,实现了一种结构紧凑、频率选择性较高的超宽带(UWB)带通滤波器。修改的多模谐振器能产生5个模式和2个在高低截止频率附近的传输零点,提高了频率选择性。在滤波器的基础上,通过加载谐振器,形成在8.11 GHz处具有陷波特性的超宽带带通滤波器。利用HFSS13.0验证设计原理。仿真结果表明,该超宽带带通滤波器通带为2.61~11.21 GHz,陷波频率为8.11 GHz,能有效抑制X频段(7.91~8.31 GHz)卫星通信系统对超宽带通信系统的影响,适用于超宽带无线通信系统。     

A Coplanar Stripline Ultra-Wideband Bandpass Filter With Notch Band

In this letter, a design of a compact coplanar stripline ultra-wideband bandpass filter with a narrow rejection band is reported. The filter characteristic is obtained by using stepped impedance open-circuited series stubs. It is shown that the rejection band can be placed at a desired frequency by tuning the width of the high impedance section of the series stub. Full-wave simulated and experimental results of a filter prototype are presented.