• The Journal of the Acoustical Society of Korea
• /
• v.20 no.3
• /
• pp.83-90
• /
• 2001

Conventional SAW duplexer filters employ a 1/4 wavelength transmission line, which causes difficulty in fabrication of the strip line on the package. Its manufacturing process is also complicated, because it needs integrating process of the separate transmitting filter, receiving filter and isolation circuits. This paper concerns development of a new structure of the duplexer filter that has all the transmitting filter, the receiving filter and the isolation circuit as a one chip device. For composition of the duplexer, we design the component SAW ladder filters and the isolation network consisting of lumped inductor and capacitor elements. Performance of the whole duplexer is optimized by the nonlinear multivariable minimization of a proper target function, and the result is compared with that of commercial filters.

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.393-396
• /
• 2000

기존의 탄성표면파 듀플렉서 필터는 1/4 파장 정합선로를 이용한 격리회로를 이용하기 때문에 패키지 상에 스트립라인을 구성하는 제작상의 어려움이 있다 본 연구에서는 격리회로가 송신용, 수신용 필터와 함께 온칩상에 위치할 수 있는 새로운 형태의 탄성표면파 필터를 설계하였다. 그 과정으로 송수신 대역을 각각 담당하는 사다리형 필터를 설계하였고, 집중소자 즉, 인덕터와 캐패시터로 구성되는 탄성표면파 듀플렉서 필터의 격리회로를 구성하였으며, 우수한 성능을 가질 수 있도록 각각의 집중소자들의 값을 최적화하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.1
• /
• pp.85-92
• /
• 2002

In this study, we analyzed and experimented micro-strip line inductors and capacitors for a SAW duplexer, an important devise for mobile communication. For SAW duplexers, micro-strip line lumped elements must have small impedance values, below several tens of nH or several tens of pF, and a small area pattern. In this study, we performed theoretical analysis of flat line type, meander line type, and spiral line type inductors and interdigital capacitors on a LiTaO$_3$ Piezo-crystal. We proposed a measurement method to evaluate small values of lumped elements accurately with network analyzer. In experiments, we confirmed validity of the theoretical analysis method through fabrication and characterization of micro-strip line lumped elements. The analysis method in this paper can be applied to SAW duplexers well as other microwave devices.