Ltcc Diplexer Research

As the wireless communication devices and personal electronic equipments are used more and more widely, smaller and thinner electronic products become more and more popular and have large potential markets. This trend speeds up the miniaturization of components. The Low temperature co-fired ceramic (LTCC) technology has many advantages on miniaturization and has been adopted in many fields. There are many papers discussing and researching LTCC technology and multilayer filters implemented by it, but the miniaturization of duplexer, an important component which would be essentially used in a communication or radar system, has not been concerned enough yet. It may because of the complication of duplexer itself and the high circuit density of LTCC components.Combining LTCC technology and duplexer design together, this paper began from theory of filter and duplexer design, then discussed the structures of achievable LTCC duplexer and described three different kinds of duplexers for the LTCC technics, which are LTCC even impedance duplexer, LTCC impedance transferred duplexer and lumped elements and stripline adopted duplexer. This paper also presented two lowpass and highpass LTCC filters with impedance transfer ability, related to the duplexers. The components were simulated and optimized by HFSS (High Frequency Structures Simulator) of Ansoft corporation, a full-wave three-dimension simulation software provider. The simulation results of the components were all better than the project requirements and the designed components had been scheduled to be produced on LTCC processing line.The component designs mentioned in this paper included the way to design impedance transferred lowpass and highpass filters, design and implementation of lumped LTCC duplexer, a approximate way to realize ideal striplines and so on, which are not only useful to LTCC duplexer design, but also worth to be used as reference in other component designs.