C波段LTCC宽边耦合叠层滤波器设计

C波段LTCC带通滤波器的设计,由于其谐振器采取集中LC元件,其Q值偏低,且LTCC厚膜集中元件大小在C波段相对偏大,为此在设计方面主要考虑利用传输线结构的分布参数谐振单元。分布参数宽边耦合谐振单元耦合系数大,特别适合中宽带滤波器设计。文章根据滤波器指标要求,通过电路综合出滤波器的耦合系数及外部Q值。然后利用LTCC多层优势,实现宽边叠层耦合谐振单元的C波段滤波器。     

小型化三维发夹型LTCC宽带带通滤波器

利用低温共烧陶瓷(LTCC)工艺,通过通孔互联实现了三维结构的发夹型宽带带通滤波器。该结构将谐振单元的横向尺寸转移到z轴方向实现,有效减小了滤波器的尺寸并且谐振器间的耦合系数为传统结构的1.6倍。利用五个谐振器结构实现较宽的频带(>30%)和较好的选择特性。设计并实际制作了中心频率10 GHz的LTCC带通滤波器,3 dB带宽为8.8～12.1 GHz,实测指标与设计仿真结果较为吻合。     

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。     

小型化LTCC 3dB电桥的设计与制作

采用两条宽边耦合的带状线方式完成了一种小型化LTCC 3 dB电桥的设计和制作。两条耦合线采用蛇形线形式,带状线的两个接地层分别在LTCC基板的顶面和底面,并且通过四个侧面印刷导体连接起来。两条耦合线印刷在LTCC基板内部中间层,并且通过印刷特殊介质层实现隔离。结果表明,控制介质层的厚度和耦合线的对位达到了3 dB的耦合度,实现了器件小型化。     

L 波段带双零点的窄带LTCC 滤波器设计

本文应用LTCC 技术设计了一个L 波段二阶Chebyshev 窄带带通滤波器。该滤波器集成在9 层LTCC 介质中,采用等效集总元件（电容电感)结构,充分利用LTCC 的三维封装结构减小滤波器体积,通过谐振单元中集总元件的串并联产生两个带外传输零点,同时调整谐振单元耦合间距控制带宽。滤波器输入输出利用金属通孔将带状线过渡到微带上。滤波器（带过渡结构）的仿真结果为：中心频率1.42 GHz,1 dB 相对带宽2.1%,插入损耗通带内最低0.5 dB, 回波损耗优于20 dB,整个滤波器体积为：4.5×4×0.87 mm3。     

一种基于LTCC技术的螺旋电感带通滤波器

本文提出一种新型的基于低温共烧陶瓷技术(LTCC)的螺旋电感带通滤波器.滤波器的设计是利用螺旋电感的自谐振和谐振单元间的电磁耦合来实现.通过HFSS仿真和等效电路分析,对滤波器结构进行了优化分析.这种滤波器具有体积小.结构布局灵活的优点,可以很好的满足器件埋置的要求.     

一种新型多层低温共烧陶瓷三级带通滤波器

提出了一种新型多层低温共烧陶瓷(LTCC)三级带通滤波器的结构及其设计方法。首先,利用电磁场仿真软件对各谐振器的谐振特性,谐振器与外部电路的耦合特性,以及谐振器之间的耦合特性进行了分析,绘制出电路设计中需要的各种曲线。在此基础上得到三级切比雪夫响应带通滤波器的尺寸和频响曲线。其次,在第1和第3级谐振器之间引入交叉耦合,并通过改变该交叉耦合的强弱,在阻带中产生位置可调节的传输零点,从而显著地增大传输零点附近的衰减。通过上述场与路相结合的设计方法,获得了尺寸小、频率选择特性好的多层LTCC三级带通滤波器。     

低温共烧陶瓷多层基板精细互连技术

微电子技术和封装工艺的发展使超大规模集成电路(VLSI)的密度越来越高,而高密度低温共烧陶瓷(LTCC)基板的制作依赖于基板内部导体的精细互连技术.为了满足LTCC多层基板高密度互连的工艺要求,必须使基板微通孔的直径及导线线宽缩小到100 μm以内.基于此,首先介绍了LTCC生瓷带层的微通孔形成与填充工艺,以及所形成的微通孔的特点;利用厚膜丝网印刷技术形成精细导线,分析了影响印刷质量的工艺参数;最后简要介绍了薄膜光刻等新技术.通过应用上述几种先进的精细互连工艺技术,极大地提高了LTCC多层基板的互连密度.     

基于新型阶跃阻抗谐振器的微带双带带通滤波器

提出了一种小型多层低温共烧陶瓷(LTCC)双带带通滤波器的结构并给出其设计方法。该多层微带带通滤波器由两个中心频率不同的滤波器组成,均用新型阶跃阻抗谐振器(SIR)作为谐振单元,有效地缩短谐振器的长度。采用多层LTCC技术实现尺寸的小型化,并且获得较高的阻带抑制。经测试表明该滤波器能够在5.2GHz和6.5GHz工作,插入损耗均小于2dB,谐波抑制能力强,在小型化微波通信系统中有着广泛的应用前景。     

基于LTCC工艺的抽头式梳状线滤波器设计

介绍了一种基于LTCC工艺的梳状线带通滤波器的设计方法,滤波器包含四个谐振单元,每个谐振单元采用多层交叠带线结构。利用电磁仿真软件HFSS提取输入输出谐振单元的外部Q值以及谐振单元间的耦合系数,通过在第一级与第四级谐振单元之间引入Z型容性耦合,在上下边带各插入一个传输零点,提高带外抑制能力。实测结果显示,滤波器在中心频率3.35GHz处的插入损耗小于3dB,-1dB带宽大于400 MHz,带外抑制在DC-2.5GHz内大于40dB,在4~8GHz内大于30dB。     

Stripline combline filters on substrates designed on high-permittivity ceramic materials

Stripline bandpass combline filters designed on high-permittivity ceramic materials are analyzed. In order to form coupling between codirectional quarter-wave resonators, they are connected in the regions of their short-circuited ends by a stripline conductor. Features of the characteristics of such filters are revealed and compared with the parameters of other ceramic microwave filters. Experimental characteristics of a stripline filter designed on a ceramics with permittivity ?_r = 38 are presented. The experimental results are in good agreement with results of computer simulation.     

Combline filters designed on symmetric stripline

Problems arising during the design of stripline combline filters, which until quite recently were considered as all-stop microwave structures, are considered. It has been shown that the electromagnetic coupling coefficient of quarter-wave stripline resonators increases with the value of material permittivity ε_r, the operating frequency, and the thickness of the filter resonators. For ε_r = 92 and a thickness of stripline resonators of 4 mm, it exceeds 12% at frequencies higher than 2.2 GHz. Two alternative versions of combline filters have been designed: a filter with a coupling strip and a filter without a coupling strip. Experimental data for a nine-resonator combline filter with a thickness of 4 mm, ε_r = 9.7, and the center frequency f ₀ = 2.4 GHz are presented. A method for increasing the selectivity of combline filters with the same number of resonators is proposed. It has been found that amplitude–frequency responses of stripline combline filters are near-symmetric, unlike the responses of microstrip combline filters.     

Serially-connected series-stub resonators for narrowband coplanar-stripline bandpass filters

In this letter, a coplanar stripline (CPS) series resonator composed of serially-connected series-stubs is proposed. This kind of resonator provides two transmission zeros close to the resonant frequency. With the proposed structure, the reactance slope parameters of the resonators are significantly increased and adjustable by changing the length ratio of the two series stubs. This is useful for designing narrowband filters which is difficult to realize with conventional series CPS resonators. The structures of the resonators are optimized for a lower radiation loss and used to design a narrowband Chebyshev bandpass filter. The simulation and experimental results show that the proposed filter provides multiple transmission zeros and high selectivity.     

Miniature broadband bandpass filters using double-layer coupled stripline resonators

A novel double-layer coupled stripline resonator structure is introduced to realize miniature broadband bandpass filters. Filters with relative bandwidth up to 60% and size less than /spl lambda//8/spl times//spl lambda//8/spl times/h (/spl lambda/ is wavelength at the midband frequency; h is the substrate height, which is much smaller than /spl lambda//8) can be fulfilled using such resonators. Two possible filter configurations are proposed in this paper: combline and interdigital. The filter synthesis procedure follows the classical coupling matrix approach that generates very good initial responses. Optimization by the mode-matching method and fine tuning in Ansoft's High Frequency Structure Simulator are combined to improve the filter performance. Two filter design examples are given to validate the feasibility. Low temperature co-fired ceramic (LTCC) technology is employed to manufacture the filters. Experimental results of the two manufactured filters are presented. The effects of LTCC manufacturing procedure on the filter performance are also discussed.     

Stripline bandpass filters with alternating coupling coefficients

This article shows the possibility in principle to design stripline comb filters with alternating signs of the coupling coefficients. The new feature of the stepped-impedance resonators of the quarterwave type was established. They provide the opposite sings of the electromagnetic coupling with adjacent resonators. Such resonators are asymmetric relative to the vertical axes, which is drawn through their middle part. The stripline passband filters with alternating signs of coupling coefficients have attenuation poles that are located to the left and to the right of the passband. Those poles improve the selectivity of such filters. The articles provide the measured characteristics of the stripline comb filter of the forth order with alternating coupling, which has the central frequency of f ₀ = 1835 MHz and the passband width of 90 MHz. The filter is constructed using a dielectric material with relative permittivity of ε_r = 92 and has the dimensions of 7.4×4.2×2 mm.     

Expanding the rejection band of planar bandpass filters

Combined stripline and microstrip filters combining a bandpass filter with stepped-impedance resonators and one or two low-pass filters are considered. Special features of the frequency characteristics of these two kinds of filters, which form the basis of this combination, are revealed. It is confirmed experimentally that, in combined planar filters, wide rejection bands exceeding a decade are provided.     

Analysis of the coupling coefficients of stripline resonators in the designs of suspended-substrate filters

Expressions for the frequency-dependent coupling coefficients of stripline resonators in miniature designs of suspended-substrate filters are obtained. The effect of the design parameters of such filters on the coupling coefficients of their resonators is theoretically studied and frequency-selective properties of the device are analyzed. It is shown that interaction between resonators at frequencies of the filter passband is predominantly inductive in the presence of small capacitive interaction and the attenuation poles of the amplitude-frequency response (AFR) observed beyond the passband are caused by the mutual cancellation of inductive and capacitive interactions. Frequency dependences of coupling coefficients can be used to explain features of the AFRs of suspended-substrate filters. It is shown that experimental AFRs agree well with theoretical AFRs calculated in quasi-static approximation with the use of 1D models.     

Synthesis of Filter-Limiters Using Ferrimagnetic Resonators

A synthesis procedure is developed for microwave band-pass filters with the Chebyshev response using orthogonal circuit resonators coupled by a ferrimagnetic resonator. A stripline ferrimagnetic resonator filter is analyzed in detail. Equations and graphs are given which allow the selection of ferrimagnetic material and size of the ferrimagnetic sample necessary to achieve a desired bandwidth and insertion loss for a given pass-band response. The theoretical behavior of these circuits as microwave power limiters is discussed and it is shown that the ratio of the limiting threshold to the filter bandwidth is a constant depending only on the pass band response shape. Experimental confirmation of the design information discussed as well as some practical methods of varying the limiting threshold.     

Hairpin-Line and Hybrid Hairpin-Line/Half-Wave Parallel-Coupled-Line Filters

A new class of microwave filters, hairpin-line and hybrid hairpin-line/half-wave parallel-coupled-line filters, is reported. This class of filters is particularly well suited for microstrip and TEM printed-circuit realizations because grounding of the filter resonators is generally not required. Hairpin-line filters have been divided into two types. The first (Type A) is characterized by having its input and output lines open-circuited at their ends. The Type A filter has been found to yield practical impedance levels for narrow to approximately 25-percent bandwidths. The second (Type B) is characterized by having its input and output lines short-circuited at their ends. However, because of space limitations, details of the Type B filter are not presented in this paper. Theoretical background and design equations for Type A bandpass filters are presented. Experimental data for several stripline filters of 5- and 20-percent bandwidths are given. Experimental results for two microwave-integrated-circuit (MIC) filters are discussed.     

Compact triple-passband bandpass filter based on new modified stepped impedance resonators

This study proposed a triple-passband bandpass filter with compact size, low loss and high passband selectivity. The filter includes two coupled stepped impedance resonators (SIRs) and two embedded stub-loaded stepped impedance resonators (SL-SIRs), connected with coupling scheme at the symmetric plane of the filter. The filter is designed to have triple-passband at 2.4, 3.5 and 5.2 GHz for worldwide interoperability for microwave access (WiMAX) applications. By properly tuning the impedance ratio and physical length ratio of the SL-SIRs, the three passbands can be easily determined, at the same time, achieving the high passband selectivity and wide stopband. Besides, the transmission zeros near passband edges of each passband are generated by the proposed filter with cross-coupling structure. The measured results are in good agreement with the full-wave electromagnetic (EM) simulation results.