Abstract:Recently, compact wireless modules are very significant parts for multi-band wireless systems such as mobile phones and compact personal computers. A low temperature co-fired ceramic (LTCC) substrate which has embedded passive components is effective technology for producing the compact modules, because this substrate is suitable for a multilayer structure and is also a low dielectric loss and a low conductor loss. Therefore, a lot of multi-band wireless systems use this technology. In the radio frequency circuits of the multi-band wireless systems, a multiplexer is one of the most important passive circuits, in order to achieve both a compact size and high performances. In this paper, we report the technology of the compact multiplexer modules using the LTCC substrate. This paper especially focuses on the multiplexer for ultra-wideband wireless systems. The multiplexer which is suitable for narrow band wireless systems is also described. Keywords: low temperature co-fired ceramic (LTCC) substrate, module, multiplexer, multi-band wireless system, surface acoustic wave (SAW) filter, ultra-wideband (UWB) Classification: Microwave and millimeter wave devices, circuits, and systems "A compact multilayer triplexer using an ultra-wideband diplexer and a low-pass filter for 2.4 GHz wireless systems," IEICE Electron. Express, vol. 9, no. 12, pp. 1075-1080, June 2012 H. Mandai, T. Tsuru, and N. Nakajima, "Advanced multi-layer ceramic surface-mount functional components for telecommunications equipment," Proc. 45th Electronic Components and Technology Conf., 1995, pp. 247-250, May 1995. [15] G. Wang, M. Van, F. Barlow, and A. Elshabini, "An interdigital bandpass filter embedded in LTCC for 5-GHz wireless LAN applications," IEEE Microw. Wireless Compon. Lett., vol. 15, no. 5, pp. 357-359, May 2005. [16] C. -C. Weng, C. -F. Chang, and S. -J. Chung, "Development of a compact low-temperature co-fired ceramic antenna front-end module," IEEE Trans. Microw. Theory Tech., vol. 56, no. 11, pp. 2483-2492, Nov. 2008 T. Ishizaki, M. Fujita, H. Kagata, T. Uwano, and H. Miyake, "A very small dielectric planar filter for portable telephones," IEEE Trans. Microw. Theory Tech., vol. 42, no. 11, pp. 2017-2022, Nov. 1994
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