No abstract

Using a combination of right-handed and left-handed transmission lines to design of miniaturized directional couplers (DC) is considered. Design of miniaturized 3-dB and 10-dB quadrature DC and a rat-race hybrid for wireless applications is presented. Design of a dual-band 3-dB DC is reported as well. All the DCs have been designed as fully-integrated multilayer LTCC structures containing no SMD components. I. INTRODUCTIONBackward-wave transmission lines (TLs) are characterized by negative dispersion and considered as 1D metamaterials [1]. They are referred to as the left-handed (LH) TLs whereas conventional TLs with positive dispersion and forward wave propagation are called the right-handed (RH) ones.Using a combination of sections of RH and LH TLs gives an additional degree of freedom that makes it possible to design passive microwave devices with improved performance and some unusual properties. Particularly, it allows i) controlling the spurious response in order to design dual-band devices [1]-[4] or devices, which are free of spurious response within a wide frequency range [5], ii) designing broadband devices [6]-[9], iii) designing miniaturized devices [5], [9].Directional couplers (DCs) find wide applications for various RF and microwave systems. Conventional branch-line DCs based on λ/4 TL sections have large size, especially in low-frequency applications. The size of DCs can be reduced drastically by means of replacing distributed TLs by artificial ones based on lumped-element LC-cells. Employment of artificial RH and LH TLs in a combination seems to be more suitable for practical implementation of DCs and makes possible a more efficient size reduction as compared with using artificial RH TLs only. Moreover, the use of LH TL is indispensable to design of a miniaturized rat-race ring.This paper presents a design of miniaturized DCs for wireless applications. Quasi-lumped-element 3-dB and 10-dB quadrature DCs and a rat-race hybrid based on artificial RH and LH TLs have been implemented on Low-Temperature Co-fired Ceramics (LTCC) boards as fully-integrated multilayer structures without using any surface-mount devices (SMD).Due to periodic resonant properties of λ/4 TL sections, the conventional DCs suffer from spurious responses at the higher

Application of LTCC and sandwlich multilaver-technologies to a design of Microwave integrated cirelits is considered. Potential benefits fbr microwave applications are discussed. Design of LTCC and sandw'lich based MICs of bandpass filters, directional couplers. and a fully integrated fiont-end module for wireless systems is presented.LIdex Terms -LTCC, inultilayer technology. MIC. filters1 directional couplers.

The LTCC and sandwich multilayer technologies as applied to design of quasi-lumped-element passive microwave devices are considered. Design of miniature high-performance bandpass filters and directional couplers for wireless applications is presented. IntroductionAllocation of passive components within several layers of integrated circuit allows designing very compact highly-integrated microwave devices. Two different thick-film technologies are suitable for manufacturing multilayer microwave integrated circuits (MICs).The Low-Temperature Cofired Ceramics (LTCC) multilayer technology is widely used for realization of passive microwave devices and integration of active and passive devices into miniature front-end modules of low cost [1]- [3]. In the LTCC process conductive patterns are deposited by screen-printing onto thin (100-200 µm) dielectric sheets, which are then stacked up, laminated, and fired simultaneously [4].Application of the sandwich multilayer technology to realize passive microwave components and devices were reported in [6]- [8]. The sandwich process [5] employs a thick (0.5-1.0 mm) ceramic substrate as the core of multilayer structure. Conductive and dielectric layers are patterned onto this substrate by means of screenprinting technique. The layers are deposited in a "series" manner with consecutive co-firing of each layer. A number of layers can be printed in different areas on both sides of the ceramic substrate. Typical thickness is 15 µm for the conductive layers and 45-60 µm for the dielectric ones. Smaller thickness of dielectric layers with respect to LTCC materials allows decreasing the area occupied by parallel-plate capacitors. At the same time, parasitic grounded capacitances are sufficiently eliminated, if through a thick substrate. The ceramic substrate employed in the sandwich structures could also play the role of PCB, onto which a front-end module is assembled. Furthermore, the sandwich process is compatible with planar thin-film technology.Both the LTCC and sandwich technologies are suitable for a realization of compact, free of spurious response microwave devices based on quasi-lumped elements. This paper presents the design of miniature bandpass filters and directional couplers for wireless applications realized using the both multilayer technologies.