Wireless power transfer (WPT) can be classified into magnetic induction, magnetic resonance, and RF radiation types, of which the magnetic resonance WPT system is especially attracting attention due to its high potential for development. The magnetic resonance system using a specific resonance frequency is applicable to small mobile devices and in-body wireless charging modules because it enables the implementation of single-input multiple-output (SIMO), where the transmitter transmits power to multiple receivers, and the miniaturization of receiving coil. The most important consideration of the magnetic resonance WPT is the optimization of the power transfer distance and efficiency, which requires a precise design and the analysis of the transmission coil. Ferrite-embedded LTCC inductors are more advantageous for WPT applications than coil inductors because of their low cost, batch manufacturing and durability. A coil with the substate size of 10.0×12.0×0.7mm3 was manufactured using the ferrite-embedded LTCC technology to miniaturize the receiver coil. The sum of power transferred from transmitter sized of 80×60mm2 to two receivers is approximately 32%, which indicates a high potential for use in small terminals or in-body modules.

A 300-GHz hetero-generous package solution with a combination of a polyimide microstrip-to-waveguide transition on low-temperature co-fired ceramic (LTCC) is presented. To assemble three parts — a metal back-short, polyimide transition, and LTCC substrate integrated waveguide (SIW) — a ridged microstructure beside the microstrip probe was implemented to reduce the air gap on the broadwall of a back-short. A back-to-back transition exhibited an insertion loss of 4.4 dB at 300 GHz and 49-GHz bandwidth with less than a 10-dB return loss. By evaluating loss of the microstrip line and SIW, we estimated the loss for a single transition, which was 0.9 dB at 300 GHz. The probe transition with ridged metal successfully suppressed the unwanted dip in transmission characteristics and eased the difficulty in assembly. The compact transition is easy to integrate in an antenna-in-package with an MMIC chip by combining suitable substrate materials for the transition and package.

A compact DC-DC convertor is proposed and fabricated by LTCC technology. Multilayer packaging structure is utilized for size reduction. Measured results are provided to show good performance and validate proposed structure. With the inductor embedded into ferrite substrate, the convertor exhibits advantages of both miniature size and high reliability compared with conventional ones.

In the millimeter-wave band, the series-fed array antenna is facing a problem of large transmission loss and narrow bandwidth by using a high-permittivity and large-loss-tangent material. In this paper, an air region is inserted in the half of the height in the LTCC waveguide of εr =6.6 and tanδ =0.013 to reduce the transmission loss. The reduction of the equivalent dielectric constant by the air insertion structure enhances both the gain and the bandwidth of the series-fed slot array. The transmission loss of the single-mode rectangular waveguide has been reduced to about 1/6 by using the partially-filled structure in the 60-GHz band. In a one-dimensional slot array, the total loss has also been reduced to about 1/7. And the 3 dB-down gain bandwidth has also been increased from 1.3 GHz to 2.3 GHz.

This paper describes latest RF Automated Test Equipment (RF ATE) technologies that include device under test (DUT) connections, a calibration method, and an RF test module mainly focusing on low cost of test (COT). Most important respect for low COT is how achieve a number of simultaneous measurements and short test time as well as a plain calibration. We realized these respects by a newly proposed calibration method and a drastically downsized RF test module with multiple resources and high throughput. The calibration method is very convenient for RF ATE. Major contribution for downsizing of the RF test module is RF circuit technology in form of RF functional system in package (RF-SIPs), resulting in very attractive test solutions.

Microstrip-line-fed broadband aperture antennas were developed in the millimeter-wave band. We have developed broadband microstrip-to-waveguide transitions to connect a microstrip line and a waveguide. The waveguide transmission line was replaced by a radiating waveguide with an aperture to compose a microstrip-line-fed aperture antenna. Two types of aperture antennas were developed. First, the microstrip substrate is fixed between the two metal plates of a waveguide with an aperture and a back-short waveguide. Second, both the microstrip feeding-line and the back-short waveguide are accommodated in the two-layer LTCC substrate. Broadband performance was achieved due to the potential of the transition. The characteristics of the developed antennas were evaluated by simulations and experiments in the millimeter-wave band.

A new kind of 3D power divider based on a half-mode substrate integrated circular cavity (HSICC) is proposed. This novel power divider can reduce the size of a power divider based on normal substrate integrated circular cavity (SICC) by nearly a half. To verify the validity of the design method, a two-way X-band HSICC power divider using low temperature co-fired ceramic (LTCC) technology is designed, fabricated and measured.

A millimeter-wave termination which is tolerant to the resistance error of the embedded resistive film in a multi-layered LTCC substrate has been developed. The tolerance to the resistance error can be accomplished using two bifurcated strip lines overlapping with the resistive film, whose lengths are different form each other. It has been experimentally demonstrated that the proposed termination configuration is effective to enhance the tolerance to resistance error of the embedded resistive film in the LTCC substrate.

This paper presents a compact and highly integrated triple-band RF front-end module (FEM) for worldwide interoperability for microwave access (WiMAX) applications using multilayer low temperature co-fired ceramic (LTCC) technology. The proposed RF FEM is composed of a TX triplexer, an RX triplexer, and a TX/RX switch. Both TX and RX triplexers are fully embedded in an LTCC substrate and the TX/RX switch is placed on the substrate. The TX triplexer consists of 2- and 5-GHz lowpass filters, a 3-GHz highpass filter, and a matching circuit. On the other hand, the RX triplexer consists of miniaturized 2-, 3-, 5-GHz coupled-resonator bandpass filters and a matching circuit, which are stacked up for space saving. In TX path, the RF FEM provides an insertion loss of 1.8 dB, 2.1 dB and 2.5 dB at 2-, 3-, and 5-GHz band, respectively, with a high second-harmonic suppression characteristic. In RX path, the RF FEM also provides a low insertion loss at three passbands with high attenuation at other passbands. The size of the proposed RF FEM is only 4.0 mm5.0 mm with a substrate thickness of 0.73 mm. The measured results are in good agreement with the simulated results.

A new comprehensive method to suppress the spurious modes in a BPF is proposed taking the multi-strip resonator BPF as an example. It consists of disturbing the resonant frequency, coupling coefficient and external Q of the higher-order modes at the same time. The designed example has shown an extraordinarily good out-of-band response in the computer simulation.

In this paper, a resonator based on composite right/left handed transmission line concept is discussed. This resonator excites --1st order resonance mode. We start with half-wave resonators consisting of two unit cells of a composite right/left handed transmission line. From the simulated field distributions, the center of these half-wave resonators can be short-circuited to obtain a quarter-wave resonator in the --1st mode. Susceptance slope parameters are calculated for the resonator. Then this resonator is applied for a 2-pole filter made by LTCC, which can be designed with standard filter design theory owing to the slope parameter. The dimension of the experimental filter implemented by LTCC is 2.5 mm by 1.35 mm by 0.52 mm. The insertion loss is 1.80 dB at the 2.4 GHz band. Good agreement between measured and computed results is obtained.

In this paper, we utilize low temperature co-fired ceramic technology (LTCC) to realize a modified short-circuited stub bandpass filter suitable for ultra-wideband (UWB) applications. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate (∈ r = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter is fabricated and measurement results show that it has an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49% has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are 480.57 mm3.

A strip line broadside hybrid coupler which is tolerant to manufacturing errors in a multi-layered LTCC substrate has been developed. The tolerance to a displacement error and a thickness variation in the multi-layered LTCC substrate can be achieved by using the tandem arrangement of diagonally shifted coupled lines with adjacent ground walls. It has been demonstrated that the coupling deviation from designed characteristics in our proposed hybrid coupler is very small.

Transitions between a post-wall waveguide and a microstrip line are proposed as the key components for cost-effective millimeter-wave modules. A transition with a coaxial structure is investigated for LTCC laminated layers and 11.3% bandwidth for the reflection smaller than -15 dB is realized in 60 GHz band. The overall connector loss with 1 cm post-wall would be about 0.8 dB. The degradation due to fabrication error is also assessed. The transition in LTCC substrate fulfills electrical and manufacturing demands in millimeter-wave bands.

For V-band applications, this paper presents a fully embedded multi-layer dielectric waveguide filter (DWGF) with very low insertion loss and small size, which does not need any more assemblies such as flip-chip bonding and bond wires. The top and bottom plane are grounded, and therefore, although we make a metal housing, there will be no resonance occurrences. Especially, the proposed structure is very suitable for MMICs interconnection because the in/output pads consist of conductor backed co-planar waveguide (CBCPW). The filter is formed incorporating metallized through holes in low temperature co-fired ceramic (LTCC) substrates with relative dielectric constant of 7.05. The total volume of the filter including transitions is 4.5 mm2.65 mm0.4 mm. A fabricated DWGF with four transitions shows an insertion loss and a return loss of 2.95 dB and less than 15 dB at the center frequency of 62.17 GHz, respectively. According to the authors' knowledge, the proposed filter shows the lowest insertion loss among the embedded multi-layer millimeter-wave filters ever reported for 60 GHz applications.

This paper presents a design procedure of multilayer single-input/single-output dual-band filters of small size fabricated in high-permittivity LTCC (Low Temperature Co-fired Ceramic) substrates. The present dual-band filter, with pass bands of 950 MHz and 1.9 GHz, consists of two single-band filters each one of which has a matching circuit for controlling the input impedance in the pass band of the counterpart. Discussed first in this paper is a dual-band filter that has the matching circuit connected to the single-band filters externally. Then, a dual-band filter with the matching circuit embedded in its body is investigated together with metallization patterns of the matching elements. Presented finally is a very small single-input/single-output dual-band filter suitable for dual-band wireless communication systems.

This paper presents an even harmonic quadrature mixer (EH-QMIX) with a simple filter configuration and an integrated LTCC module including LNAs, band rejection filters (BRFs), and the proposed EH-QMIX for W-CDMA direct conversion receiver (DCR). Since the DCR has no spurious responses, a BRF instead of a high-Q band pass filter can be applicable for eliminating undesired signals and it can be built in the LTCC substrates easily. As LO frequency is half of RF frequency in the EH-QMIX, diplexer can be composed of simple filters and it can be also integrated in the substrates. As a result, the whole RF circuits of the EH-DCR using a proposed EH-QMIX are integrated in the LTCC module and miniaturization of the receiver is achieved. Moreover, in order to suppress the degradation of the amplitude and the phase imbalances in the quadrature mixer caused by interferences of signals, RF characteristics of the circuits in the mixer such as reflection coefficients, isolations are discussed. A developed LTCC module shows good performances for W-CDMA direct conversion receiver.

A conventional waveguide filter is usually composed of a waveguide which is set with irises and posts inside. When dielectric material is not loaded inside the filter, the filter is too large to mount it on a planar circuit even if the frequency band is as high as the millimeter-wave band. In this paper, we propose a dielectric waveguide filter using LTCC (Low-Temperature Co-fired Ceramics) which can be mounted on a planar circuit. The dielectric waveguide filter using LTCC is composed of a dielectric-loaded waveguide including posts (via holes) and TEM-TE10 converters. The design method of the filter is shown and comparison of the simulated and the experimental results in the 6 GHz band is demonstrated. The simulated results agreed well with the experimental ones. To improve the attenuation characteristics, particularly at the above pass-band frequencies, an attenuation pole is added using a cross patch set inside the LTCC filter in the 25 GHz band. The effect of the cross patch is confirmed using the same simulation method as used for the 6 GHz band. As a result, it is confirmed that the cross patch is very useful for improving the attenuation characteristics at the above pass-band frequencies.

Fully embedded spiral inductors in a low loss dielectric multi-layer were designed and fabricated using a low temperature co-fired ceramics (LTCC) technology for RF SIP (system in package) integrations. The line width/space and the number of spiral layers were optimized within five layers of LTCC dielectric for high Q-factor, high self-resonant frequency (SRF), process easiness, and compact size. The embedded multi-layer spiral inductors reveal better performance in terms of Q-factor, SRF and the effective inductance Leff than planar spiral inductors of the same dimension and number of turns. The optimized multi-layer spiral inductor shows maximum Q of 56, Leff of 6.6 nH at Qmax and SRF of 3.6 GHz while planar spiral inductors have maximum Q of 49, Leff of 5.8 nH at Qmax and SRF of 3.0 GHz.

We have devised and implemented a new low-loss microstrip transmission structure on LTCC substrate by including void cavities in the dielectric layer between conductor strip and ground plane. Measurements of λ/4 T-resonators with the novel microstrip structure reveal total loss of 0.0126dB/mm and Q-factor of 267 at 15.85GHz. The dielectric loss is analyzed as small as 0.0005dB/mm at the frequency, and that is equivalent to an improvement of a factor of 18 compared to the conventional LTCC microstrip structure. The proposed microstrip structure with the embedded void cavities is suited for low loss LTCC based RF-MCM applications.