• Title, Summary, Keyword: Ladder filter

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Optimal Design of Ladder Type SAW Filters (사다리형 SAW 필터의 최적 설계)

  • 노용래
    • The Journal of the Acoustical Society of Korea
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    • v.18 no.1
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    • pp.16-24
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    • 1999
  • Design of SAW ladder filters has been performed by a rather trial and error method, that is, by modifying the design variables step by step until designed performance of the filter satisfies given specifications. In this work, optimal design method has been developed that automatically determines the detailed pattern of the SAW ladder filter to meet the specification once desired performance is given. As a first step for the development, the analysis tool for the SAW ladder filter has been produced by means of the Smith equivalent circuit analysis technique, and its validity has been verified through comparison of its calculation result with experimental data. With the analysis tool, we have investigated the performance variation of the filter with the change of its design factors, and the result has led to the optimal design algorithm. Validity and efficiency of the algorithm has been checked through test design of several SAW ladder filter samples on the market.

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Fabrication of Film Bulk Acoustic Wave Filters with Ladder and Stacked Crystal Filter Types (Ladder 형과 SCF 형의 구조를 가지는 FBAR 필터의 제작)

  • ;;Mai Linh
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.630-632
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    • 2003
  • In this paper, we present the fabrication and performance of FBAR filters with ladder and stacked crystal filter (SCF) types. The structure of the unit resonator in our work is the solidly mounted resonator (SMR) with W/SiO$_2$ multi-layer reflectors, the return loss of of which show -24dB at resonant frequency of -2.0GHz. The $K^2$eff, Q$_{s}$, and Q$_{p}$, indicating the performance of resonator were 3.24%, 6,363 and 6,749 and were calculated for the resonator with the resonance area of 21200${\mu}{\textrm}{m}$$^2$. Based on this unit resonator, FBAR filters with ladder and SCF types were fabricated and compared. The sizes of filters were 800$\times$2000(${\mu}{\textrm}{m}$$^2$) for the ladder type and 600$\times$500(${\mu}{\textrm}{m}$$^2$) for the SCF type.e..

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Optimization of Withdrawal Weighted SAW Ladder Filters (위드로월 가중형 SAW 사다리 필터의 최적화)

  • 이영진;이승희;노용래
    • The Journal of the Acoustical Society of Korea
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    • v.21 no.2
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    • pp.102-109
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    • 2002
  • This paper proposes a new design algorithm to optimize the withdrawal weighted SAW ladder devices, Withdrawal weighting on SAW resonators gives enhanced bandwidth and transition band characteristics, so an optimization algorithm was developed for ladder type SAW filters. To illustrate the validity of the technique, this method was applied to the design of RF band CDMA TX SAW filters, and the design results were confirmed to show good agreement with experimental performance.

Design of a Continuous-Time Filter Using the Modified Chebyshev Function and DDA (개선된 Chebyshev 함수와 DDA를 이용한 연속시간 필터 설계)

  • 최석우;윤창훈;김동용
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.32B no.12
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    • pp.1572-1580
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    • 1995
  • In this paper, a modified Chebyshev low-pass filter function is proposed. The modified Chebyshev filter function exhibits ripples diminishing toward .omega. = 0 in the passband. So, the modified filter function is realizable in the passive doubly-terminated ladder network for the order n even or odd, thus lending itself amenable to active RC or switched capacitor filters through the simulation techniques. Besides the passive doubly-terminated ladder realizability, lower pole-Q values of the modified function are accountable for improved phase and delay characteristics, as compared to classical function. We have designed the 6th order passive doubly-terminated network using the modified function. And then a continuous-time DDA(Differential Difference Amplifier) filter, which has no matching requirement, is realized by leap-frog simulation technique for fabrication. In the HSPICE simulation results, we confirmed that the designed continuous-time DDA filter characteristics are agreement with the passive filter.

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Air-Gap Type TFBAR Ladder Filters for Wireless Applications

  • Kim, Kun-Wook;Goo, Myeong-Gweon;Yook, Jong-Gwan;Park, Han-Kyu
    • Journal of electromagnetic engineering and science
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    • v.2 no.1
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    • pp.34-38
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    • 2002
  • TFBAR filters for wireless applications are simulated and fabricated. A CAD model is used to analize the air-gap type single resonator and MBVD model is used far filter design. Aluminum nitride is used as the piezoelectric material with platinum electrodes. To verier the CAD model, simulated and measured results are compared far various top electrode thicknesses, and the agreement is within 0.5 % for the parallel resonance frequency. Various types of the ladder type band pass filters are predicted and their responses are compared with measured frequency data.

Fabrication of 800MHz Duplexer Using SAW Filter (800MHz 대역 이동통신 단말기용 듀플렉서의 설계 및 분석)

  • 이택주;권희두;정덕진
    • Proceedings of the IEEK Conference
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    • pp.245-248
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    • 2001
  • In this paper, we have investigated the design technique and fabricated the surface acoustic wave (SAW) filter for duplexer, which consists of Tx. and Rx. filter, and antenna terminal. For Tx. and Rx. bandpass filters we used the one-port SAW resonators with n-section ladder structure. The structure is composed of couples of series-arm resonators and parallel-arm resonators. RF filter using ladder structure was designed and fabricated on 36$^{\circ}$Y-X LiTaO$_3$ substrates. Designed filters, insertion loss is less than 1.5dB, the bandwidth is more than 25MHz, rejection band level is less than -30dB and center frequency is 820MHz.

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A Study on compensation of Frequency Distortion of SCF by Using Prewarping Procedure (Prewarping법을 이용한 SCF의 주파수 #곡 보상에 관한 연구)

  • 최민호;김도현
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.22 no.5
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    • pp.69-74
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    • 1985
  • In this paper five-order Butterworth Low pass active RC filter is designed by using FDNR (Frequency Dependent Ncgative Resistor) Method from LC ladder filter having the lowest sensitivity. In process of Transformation to SCF (Switched Capacitor Filter) from active RC filter, Bilinear Z Transfomation method is utilized. By the design of SCF using the bilinear Z transform method the problem of aliasing can be avoided, but the frequency distortion is generated. The transformation from analog filter to digital filter is not equal in the region of the cut off frequency caused by this effect. Avoiding the problem of this effect, we use prewarping method. The result shows that the prewarped SCF makes more remarkable improvement in the frequency distortion than SCF which is transformed by using bilinear Z transform.

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Derivation of Transfer Function for the Cross-Coupled Filter Systems Using Chain Matrices

  • Um, Kee-Hong
    • International journal of advanced smart convergence
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    • v.7 no.1
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    • pp.7-14
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    • 2018
  • In this paper, we derive a transfer function of cross-coupled microwave filter systems by using a characteristics of chain matrices. Depending on the lumped element of capacitor or inductor, the cross-coupled system is negatively- or positively system. We used a ladder network as a starting system composed of several subsystems connected in chain. Each subsystem is descrived by Laplace impedance. By solving the transmission zero characteristic equation derived from the cascaded subsystems, we can find the zeros of filter system with externally cross-coupled lumped elements. With the cross-coupled elements of capacitors, the numerator polynomial of system transfer function is used to locate the quadruplet zeros in complex plane. We show the polynomoials of numerator and denominator of cascaded transfer function, obtaining the zeros of the cross-coupled system.

Effect of Size of Sintered Body on Resonant and Filter Characteristics in Pb(Sn1/2Sb1/2)O3-PbTiO3 Piezoelectric Ceramics (Pb(Sn1/2Sb1/2)O3-PbTiO3계 소결체의 직경변화가 공진 및 필터특성에 미치는 영향)

  • 임진호;조상희
    • Journal of the Korean Ceramic Society
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    • v.25 no.4
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    • pp.309-314
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    • 1988
  • In this study, the effect of the size of sintered body on resonant and filter characteristics in Pb(Sn1/2Sb1/2)O3-PbTiO3 piezo-electric system were investigated. The attenuation characteristics of ring-dot type and ladder type filter were also investigated. As the size of sintered body was decreased, the resonant characteristic(Fr, Fa) and the center frequency(Fo) were increased. As the poling field was increased, the Kp and bandwidth were increased. The big difference between rign-dot type and ladder type was the sharpness of bandwidth, selectivity and the movement of center frequency.

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A Study on the Out-of-Band Rejection Improvement of TFBAR Ladder Filter using On-Wafer Inductors (기판상의 인덕터를 이용한 박막 공진 여파기의 대역 외 저지특성 개선 연구)

  • 김종수;구명권;육종관
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.3
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    • pp.284-290
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    • 2004
  • In this paper, two types of thin nim bulk acoustic resonator(TFBAR) ladder filters are desisted and fabricated to analyze the effects of on-wafer inductor integration. To suppress the overmode phenomenon a 1 $\mu\textrm{m}$ thick air-gap is fabricated under the TFBAR and aluminum nitride is used for piezoelectric material, while platinum is employed for the top and bottom electrodes. The Tx filter in a duplexer, which usually has a steeper skirt characteristics o the right side of the passband, is designed with four serial and two shunt resonators, namely, a 4/2 stage. Similarly, the Rx filter is devised with a 3/4 stage to create a mirrored image of the Tx filter passband characteristics. Fabricated on-wafer spiral inductors with underpass reveals the Q factor of 5~9 at 2 ㎓. Inductor integrated filters have approximately 10 to 12 ㏈ out-of-band rejection improvement, when compared to the original filters.