Journal of the Korea Institute of Information and Communication Engineering (한국정보통신학회논문지)

The Korea Institute of Information and Commucation Engineering (한국정보통신학회)
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A Study on the Simulator for the fabrication of bandpass filter for the Wide-band Codeless Division Multiple Access

광 대역 통과 필터 제작을 위한 모의 실험기

  • 유일현 (세명 대학교, 컴퓨터 응용과학과)
  • Published : 2004.06.01
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Abstract

We have studied a method to fabricated a Surface Acoustic Waves (SAW) filter for Wide band Codeless Division Multiple Access(WCDMA) was formed on the Langasite substrate and was evaporated by Aluminum-Copper alloy and then we developed a simulator using the mathematica package. And, we can design and fabricate the Slanted finger Inter-digital Transducer (SFIT) for the purpose to decreased the ultimate rejections on side of the electrodes, and performed computer-simulation by simulator. Also, we have employed that the block weighted type Inter-digital Transduce(IDT) as input transduce of the filter and the withdrawal weighted type IDT as an output transducer of the filter in order to minimize effect of diffractions. We have employed that the number of pairs of the input and output IDT are 50 pairs and the thickness and the width of reflector are $5000\AA$, and $1\lambda/4(\cong3.6{\mu}m)$, respectively. Also the width of IDT' finger and the space between IDT' finger and reflector are $1\lambda$/16 and 1\lambda$/8, respectively. Frequency response of the fabricated SAW bandpass filter has the property that center frequency is about 190MHz, bandwidth at the 3dB is probably 4MHz and out-band attenuation is -60dB approximately.

WCDMA용 SAW 필터를 제작하기 위하여 mathematica package를 이용한 모의 실험기를 개발하였으며, 전극재료로는 Al-Cu를 사용하였다. 모의실험한 자료를 바탕으로 전극에서 발생하는 ultimate rejection을 줄이기 위해 SFIT형태의 필터를 설계 및 제작하였다. 회절에 의한 현상을 최소화하기 위해 필터의 입력단은 block weighted IDT 형태로, 출력단은 withdrawal weighted IDT형태로 구성하였다. Langasite 기판위에 형성시킨 입 출력 빗살무늬 변환기 전극 수는 50쌍, 두께와 폭은 5000$\AA$와 1λ4(((equation omitted) 3.6$\mu\textrm{m}$)로 하였으며, IDT 전극 폭과 전극간격 은 각각 1λ/16와 1λ/8로 하였다. 제작한 SAW 필터의 특성은 중심주파수는 190MHz, 통과대역은 4MHz이며 저지대역은 -60dB이하로 측정되었다.

Keywords

References

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