Right/left-handed transmission line LTCC directional couplers

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

Compact LTCC Balun using L-C Embraced Structure for 128 MHz 3T MRI Applications

“…Comparisons of size and performance are listed in Tab. 1, which shows the proposed balun has the largest number of L-C elements but the smallest size, lowest amplitude imbalance and lowest phase difference between the through and coupled port among [9][10][11][12][13].…”

“…Vertical integration using low temperature co-fired ceramic (LTCC) and Liquid Crystal Polymer (LCP) technologies have been reported for miniaturization of passive components. However, the multilayered vertically-interdigitalcapacitors (VICs) and spiral inductors have no further enhancement of capacitance/inductance and improvement of miniaturization [11][12][13][14]. Although inductor and capacitor (L-C) stacked resonator has been reported for circuit miniaturization, it increases both the number of LTCC layers and fabrication cost [15].…”

Miniaturized VHF‐band LTCC balun using L‐C surrounded resonator

“…Vertical integration using low temperature co‐fired ceramic (LTCC) and liquid crystal polymer technologies have been reported for miniaturization of passive components. However, the multilayered vertically interdigital‐capacitors (VICs) and spiral inductors have no further capacitance/inductance density enhancement and improvement of miniaturization 4–9 . A miniaturized coupler is proposed using traditional VIC and spiral inductors, however little innovation is made in VIC and spiral inductors 9 .…”

Tunable microwave devices based on left/right-handed transmission line sections in multilayer implementation

“…Using the lumped LC-equivalents of the quarter-wavelength RH/LH sections of distributed TLs, one can design directional couplers with drastically reduced dimensions keeping the same performance [14]. Involving tunable capacitances in RH/LH TL sections enables the design of tunable microwave devices.…”