Low-temperature Co-fired Ceramic Filter Research Articles

Ultra-Low-Loss Millimeter-Wave LTCC Bandpass Filters Based on Flexible Design of Lumped and Distributed Circuits

The design of ultra-low-loss millimeter-wave (mm-wave) low-temperature cofired ceramic (LTCC) bandpass filters is proposed by merging the lumped and distributed circuits in this breif. By inserting a ground plane inside the filter, the cross talk between quasi-lumped capacitors and distributed microstrip lines can be highly reduced. Accordingly, the lumped or distributed circuits can be analyzed and designed flexibly for further performance improvements. To alleviate the design complexity, a lossy equivalent circuit model is introduced and verified for the proposed LTCC bandpass filter. Based on the equivalent circuit, the techniques for enhanced stopband rejection and low insertion loss can be both obtained. For experimental verification, two 27 GHz LTCC bandpass filters are designed, fabricated, and measured. Very low insertion losses of only 0.73 dB and 0.84 dB, wide stopband, and multiple transmission zeroes are realized, indicating the proposed LTCC filters good candidates for 5G system-in-package applications.

Compact Ku‐band LTCC bandpass filter using folded dual‐composite right‐ and left‐handed resonators

A compact Ku-band bandpass filter is proposed by using low-temperature cofired ceramic (LTCC) technology in this Letter. For miniaturisation, the folded dual-composite right- and left-handed (D-CRLH) resonator is introduced. By folding the inter-digital capacitor and microstrip section inductor in multiple metal layers, the circuit size of D-CRLH resonator can be reduced to one third of the planner one. Furthermore, the additional transmission loss caused by reverse currents is also investigated. To this end, a very compact LTCC filter is designed, fabricated, and measured, with the core circuit size smaller than 0.91 × 0.95 × 0.29 mm 3 . The minimum insertion loss is 1.95 dB at 13 GHz while with wide stopband suppression from 14.3 to 33.1 GHz.

Compact and narrowband LTCC filter using vertically stacked end‐coupled resonators

ABSTRACTA compact and narrowband low temperature co‐fired ceramic (LTCC) bandpass filter (BPF) is proposed using vertically stacked half‐wavelength end‐coupled resonators. The multilayered end‐coupled stripline resonators are stacked and buried into LTCC substrate for vertical end‐coupling and size reduction. The coupling strength between adjacent resonators is adjustable by offsetting the intermediate ground layer. A narrowband fractional bandwidth (FBW) of 1.9% and a significant size reduction of 80% are achieved. Measurements agree with the simulation results well. Performance and size reduction comparisons and discussions are also implemented. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:86–89, 2017

Design of compact dual‐passband LTCC filter exploiting stacked QMSIW and EMSIW

A dual-passband low-temperature co-fired ceramic (LTCC) filter with a stacked quarter-mode substrate-integrated waveguide (QMSIW) and an eighth-mode SIW (EMSIW) on LTCC substrates is presented. By exploiting the QMSIW and EMSIW cavities, the filter has a dual passband with high selectivity and compact size. The experimental filter exhibits two passbands, one is centred at 5.4 GHz with an insertion loss of <1.7 dB, and a 3 dB bandwidth of 13%. The other is centred at 8.3 GHz with an insertion loss of <1.5 dB, and with a bandwidth of 12.9%. The volume of the filter is only 6.5 × 6.5 × 1.2 mm3.

The Effect of Self-Heating on the Performance of a Tunable Filter With Embedded Windings in a Ferrite LTCC Package

Traditionally, ferrite-based tunable filters are biased by large and bulky electromagnets, which require high currents to overcome the dissipated fields at the air interface between the electromagnet and the ferrite substrate. This problem has been solved by implementing the windings inside the package using ferrite low-temperature co-fired ceramic (LTCC). However, these embedded windings, which are densely packed, generate heat that affects the characteristics of the ferrite material. In this paper, we investigated the heat effects due to embedded windings in ferrite LTCC filters. We also incorporated the heating effects into an electromagnetic simulation model and achieved a good agreement between the simulations and the measurements. We found that increasing the temperature of the filter module from 0 °C to 190 °C by external heating causes the center frequency of the filter to shift by about 1 GHz. Alternatively, when a dc current is passed through the bias windings, heat is generated in the windings to a temperature of 250 °C measured at 260 mA of current. This heat causes the tunability of the filter to increase by more than 2%.

LTCC ultra wide band filter

This article presents the analysis of ultra wide band (UWB) filter designed using a symmetrical three parallel coupled line resonator in low temperature co-fired ceramic (LTCC) medium. The ground plane with an aperture incorporated in it improves the coupling. Based on circuit models, the designed UWB filter has been analyzed, and the results have been confirmed by experiments. The filter has been realized with Dupont LTCC tape DuPont 951 (that has dielectric constant of 7.8). Maximum insertion loss of the experimental filter is 1.5 dB. The group variation over the pass band of the filter is within 0.2 ns. Dimensions of the experimental LTCC filter are 20 × 10 × 0.72 mm. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2580–2583, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26311

Compact wide‐band millimeter‐wave LTCC filter using trapezoidal resonator with fractal‐shaped defection

AbstractThis article presents multilayer low temperature cofired ceramic (LTCC) millimeter wave filters using trapezoidal resonator with fractal‐shaped defection.Operation principle of the resonators is given in detail. The resonators exhibit good electrical performances, compact dimensions and high integration in multilayer dielectric. The LTCC filters implemented in a stripline configuration have a volume of 4.5 × 2.5 × 0.6 mm3. The performance of the filter is simulated by full‐wave electromagnetic simulator‐Ansoft HFSS. The proposed filter is fabricated on six layers of a 100‐μm LTCC substrate. A fabricated prototype bandpass filter achieves a center frequency of 34.7 GHz, a bandwidth of 26.3%, and an insertion loss of 3 dB that includes input and output transitions, the experimental and simulation results closely correspond to each other. The superior features of the proposed filter make it suitable for use in millimeter wave communication systems and other applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:890–892, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25865

Design of compact wideband LTCC filter using pentagonal-shaped SIR

A compact wideband bandpass filter with a pentagonal-shaped open-loop folded step-impedance-resonator (SIR) using low temperature co-fired ceramic (LTCC) technology has been designed and fabricated. The filter is composed of three pentagonal-shaped open-loop SIRs embedded in multilayer thin ceramic to produce a compact size. The proposed topology is demonstrated with a design operating at 4.3 GHz with 44.2% bandwidth. More than 20 dB of spurious suppression from 6 to 11 GHz is demonstrated in the experimental results.

Design Enhancement of Miniature Lumped-Element LTCC Bandpass Filters

We present a novel methodology for the design of miniature lumped element components embedded in a low-temperature co-fired ceramic (LTCC) package. The entire process, from initial schematic design, through individual element design, to complete device optimization is discussed. The design and fabrication of novel miniature lumped element LTCC filters is used to validate the proposed methodology. Commercial software tools are used to accurately model and simulate all aspects of the devices to ensure design success. In addition, the filters occupy only 0.03 lambda times 0.05 lambda times 0.004 lambda of a conventional low-permittivity LTCC substrate, which is among the smallest sizes reported. An advantage of these filters is that they use a true third-order topology with three multilayer L-C resonators, leading to superior stopband performance. For the first time, measured results are shown for two new bandpass filters targeted for global positioning system applications. Measured results are in good agreement with the simulations and show an insertion loss of 2.8 dB and a return loss of 21.3 dB at the center frequency of 1.64 GHz.

A Fully Embedded LTCC Multilayer BPF for 3-D Integration of 40-GHz Radio

This paper demonstrates a low loss fully embedded multilayer bandpass filter (BPF) using low-temperature cofired ceramic (LTCC) technology for 3-D integration of 40-GHz multimedia wireless system (MWS) radio. The LTCC filter implemented in a stripline configuration occupies an area of only 5.5 times 2.3 times 0.6 mm including shielding structure and coplanar waveguide (CPW) transitions. The measured insertion loss was as small as 1.9 dB at a center frequency of 41.8 GHz, and the return loss was 12.2 dB including the loss associated with two CPW-to-stripline transitions. This six-layer BPF showed 3-dB bandwidth of 10.5% from 39.6 to 44.0 GHz at a center frequency of 41.8 GHz and suppressed the local oscillator (LO) signal to 20.2 dB at a local oscillator frequency of 38.8 GHz, making it suitable for the 40 GHz MWS applications.

Quasi-dual-mode microstrip spiral filters using first and second harmonic resonances

The range of bandwidths that can be implemented using spiral microstrip resonators has been extended using a structure with two patterned metal layers plus a ground plane, which also enhances compactness. Each microstrip section can be regarded as a dual-mode half-wave resonator employing the fundamental and second harmonic or as two coupled quarter-wave resonators. A fourth-order and an eighth-order filter are presented, both with 50% fractional bandwidth and 600-MHz center frequency, using basic printed-circuit-board fabrication. The eighth-order filter has an active area of approximately 45 mm/spl times/18 mm, and a linewidth of 0.5 mm. The topology, suitably scaled for higher frequency, may be suited for low-temperature co-fired ceramic filters.

A high stopband-rejection LTCC filter with multiple transmission zeros

A low-temperature-cofired ceramic (LTCC) bandpass filter with high stopband rejection is presented for multistandard coexisted wireless communication applications, such as the integrated wireless local area network (WLAN)/wavelength code-division multiple access handset, the dual-band triple-mode WLANs, and the global system for mobile communications/global positioning system receivers. By improving the filter cell structure, 2n transmission zeros can be generated to achieve wide-band suppression from cascading n filter cells. The presented method provides the design flexibility of locating these transmission zeros distributed in the lower and upper stopbands. An LTCC bandpass filter with four transmission zeros has been implemented for experimental demonstration. The measured insertion loss is less than 1.5 dB at 2500 MHz, and four transmission zeros are obtained at 1.64, 1.88, 4.36, and 5.32 GHz, respectively. These result in 48-59 dB for lower stopband suppression and 38-55 dB for higher stopband reduction. This paper demonstrates that the proposed filter is extremely suitable for the multiband RF transceivers where the cross-band interference must be adequately reduced.

Simplified analysis technique for the initial design of LTCC filters with all-capacitive coupling

The paper proposes a new low-temperature co-fired ceramic (LTCC) filter configuration, which improves the stopband behavior of previous designs by using all-capacitive couplings. Moreover, a simplified analysis technique is presented to aid filter engineers in the initial design of capacitively coupled LTCC resonators. Relationships from well-known conformal mapping expressions are used to model individual parts of the filter, which are combined by standard two-port parameters. This technique is shown to agree well with measurements of previously published filters. The proposed filter configuration is then verified by results obtained with different commercially available field solvers.

Design of a 2-Pole LTCC Filter for Wireless Communications

This letter outlines the designing and manufacture of a miniaturized bandpass filter realized by low-temperature cofired ceramic (LTCC) technology for wireless products. The bandpass filter with a central frequency of 1950 MHz and a 5% passband is designed as a three-dimensional (3-D) structure based on lumped components. The design technique based on cascading overall circuit into blocks and computer-aided design of electrical circuit is presented. Experimental measurements were compared with modeling. The insertion losses in the passband (100 MHz) were less than 2 dB and the attenuation more than 20 dB in the stopband. The area occupied by the filter is 6.6/spl times/6.6/spl times/0.836 mm/sup 3/ in plane.