윤곽진동과 길이진동 공진자를 이용한 세라믹 Ladder형 필터의 특성에 관한 연구

Abstract

It was investigated about the ladder type filter composed of different kind piezoelectric ceramic resonators, a contour vibration resonator and a length extensional vibration resonator in this paper. Ceramic ladder type filters are usually made using the contour vibration resonators and the contour vibration resonator of the series arm 3 times heavier than the one of the parallel arm in the ladder type filter. In this paper the heavier contour vibration resonator, the series resonator replaced by the length extensional vibration resonator which has the heaviness and size 1/3 compared with a conventional contour vibration resonator. The composed 3 stage ladder filter has the center frequency 455[kHz], 3dB band width 10[kHz], the insertion loss 13[dB] and the selectivity 20[dB]. This resulte show the possibilitt that resonators with length extensional vibration mode can be used to compose the Ladder filter.