한국음향학회지 (The Journal of the Acoustical Society of Korea)

  • 제18권1호
  • /
  • Pages.10-15
  • /
  • 1999
  • /
  • 1225-4428(pISSN)
  • /
  • 2287-3775(eISSN)
한국음향학회 (The Acoustical Society of Korea)
권호 표지

IF 대역 SAW 필터 설계 및 제작

A Study on Design and Fabricate of a Intermediate Frequency Band SAW Filter

  • 유일현 (세명대학교 컴퓨터 응용물리학과) ;
  • 권희두 (동양화학 중앙연구소 전자재료연구실) ;
  • 정양희 (국립여수대학교 전기공학과)
  • 발행 : 1999.01.01
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초록

본 연구는 35° Y-X Quartz 기판에 낮은 형상 요소를 갖는 Code Division Multiple Access(CDMA)방식 기지국용 Intermediate Frequency (IF)단 통과대역 필터를 설계하고 제작하는 방법에 대해 연구하였다. 이 기판 위에 임펄스 모델링을 이용하여 낮은 형상 요소를 갖는 표면 탄성파 필터를 제작하기 위해 입력단에는 Apodization weighted형의 빗살무늬 변환기, 출력단에는 Withdrawal weighted형의 빗살무늬 변환기로 구성하였다. 그리고 입출력 IDT의 개수는 리플의 영향을 최소화하기 위해 Kaiser-Bessel 창함수를 이용하였으며, 각각 2200쌍과 1000쌍으로 하였다. IDT 전극의 폭은 3.6㎛, 간격은 3.5㎛였으며 두께는 파장과의 비를 고려해 6000Å으로 할 때 최적의 결과를 얻을 수 있었으며, 구경은 임피던스 정합을 위해 2mm로 하였다. 제작된 SAW필터는 중심 주파수 115.2MHz, 통과대역 폭은 1.27MHz이상, 형상 요소는 1.3이하, 삽입손실 -l5dB 및 저지대역 -45dB이하인 특성을 얻을 수 있었다.

We have studied a method to design and fabricate the Intermediate Frequency(IF) band pass filter with low shape factor which is used for CDMA base station on the 35°Y-cut X-propagation Quartz substrate. In order to fabricate a device of the low shape factor for the IF SAW filter on this substrate, we employed apodization weighted type interdigital transducer(IDT) as an input and withdrawal weighted type IDT as an output by using impulse modelling method. Also, using the Kaiser-Bessel window function, we have adopted 2200pairs and 1000pairs of input and oueut IDT respectively to minimize the effect of ripple. Furthermore, the width and the space of IDT finger are 3.6 ㎛ and 3.5 ㎛ respectively. Thus, we can have optimal results when the IDT thickness is 6000Å in consideration of the ratio of SAW's wavelength while it's aperture is 2mm for impedance matching. The fabricated SAW filter for CDMA had the property of almost 115.2MHz of a center frequency, less then 1.27MHz of bandwidth, less than 1.3 of shape factor, - l5dB of out band attenuation insertion loss and -45dB of rejection band.

키워드

참고문헌

  1. IEEE Trans.Microwave Theory and Techniques v.MMT-21 no.4 Impulse Model Design of Acoustic Suface-Wave Filters Cliton,S.;Hartmann,;Delamer,T.Bell,jr.;Ronald,C.Rosenfeld,
  2. IEEE Trans. Circuit and Theory v.CT-20 no.5 Acoustic Surface-Wave Transversal Filters George L.Matthaei,
  3. IEEE Trans. Microwave Theory Tech. v.MTT-17 800 MHz High Performance SAW Filter Using New Resonant Configuration M.Hikita,;H.Kojima,;T.Tabuchi,;Y.Kinoshita,
  4. Surface Acoustic Wave Devices and Their Signal Processing Application Colin Cambell,
  5. IEEE Trans. Ultrasonics,Ferroelectrics and Frequency Control v.UFFC-34 no.1 The Classical Truncated cosine Series Functions with Applications to SAW Filters D.C.Malocha,;C.D.Bishop,
  6. Ultrasonic Symposium Low Loss SAW Filters Utilizing the Natural Single Phase Unidirectional Transducer (NSPUDT) T.Thoravaldsson,;B.P.Abbott,
  7. IEEE Trans. Microwave Theory and Technoques v.42 no.7 Design of Mobile Phone IIDT-Type SAW Filters with Block-Like Distribution of Transducers Gerhard Fischerauer,;Bernhard Bader,;Peter Russer,;Robert Weigel,
  8. Ultrasonic Symposium Low Loss Fifters Using Group-type SPUDT Transducers D.P.Morgan,P.Durrant,
  9. IEEE Trans. on sonics and Ultrasonics v.SU-30 Optimization of quartz SAW resonator structure with grove gratings T.Uno,;H.Jurnonji,
  10. IEEE Ultrasonic Symposium Applications for Piezoelectric Leaky Surface Waves K.Yamanouchi,;M.Takeuchi,