This paper describes very compact MIC magic-Ts and their integration with planar array antennas to realize the advanced antenna modules. The orthogonal transmission modes are effectively used to arrange the preferable port layout of magic-Ts. This flexible port layout of magic-Ts is a practical feature for integration with planar array antennas. The integration of magic-Ts and planar array antennas can easily create advanced functions. A couple of array antennas based on the integration advantages are introduced to materialize this technical concept. This integration approach is of big worth to originate various kinds of advanced antennas and the wireless modules in the ubiquitous society.

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The mode-matching applications to scattering from circular and annular apertures in a thick perfectly conducting plane are reviewed. The Hankel and Weber transforms are utilized to solve the boundary-value problems of circular and annular apertures. Simple electrostatic problems are presented to illustrate the mode-matching method in terms of the Hankel and Weber transforms. Various types of Weber transform are discussed with boundary-value problems. Electromagnetic radiation and scattering from circular and annular aperture geometries are summarized. The utility of the mode-matching method in circular and annular aperture scattering is emphasized.

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WiMAX wireless communication has been rapidly developed for broadband mobile communication. Mobile WiMAX communication system uses microwave carrier of 2.5GHz frequency band and modulation is OFDM mainly. By using OFDM technique, WiMAX provide high speed and reliable communication against multi pass interferences due to the presence of obstacles in communication channels. To design excellent high performance mobile communication systems, accurate evaluation of communication system is indispensable. By using parallel FDTD, we studied fundamental characteristics of microwave propagation and scattering in urban area. We also studied wave propagation and scattering by forest and trees using FDTD method. The effects of multiple scattering and attenuation of microwave by forest are severe factors of high speed wireless communications. In this paper, signal propagation and receiving characteristics of OFDM modulated wave are studied by parallel FDTD method. Propagation, reflection, scattering, interference and delay of digital code signals in received code signals are evaluated to show the environmental characteristics. Parallel FDTD methods are applied for signal and noise analysis about several different complex models and inhomogeneous materials such as forests in long distance communication channels.

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In this paper, the design and fabrication of a miniaturized class-F 2.5GHz 8W power amplifier using a commercially available GaN HEMT bare chip from TriQuint and a Selectively Anodized Aluminum Oxide (SAAO) substrate are presented. The SAAO process was recently proposed and patented by Wavenics Inc., Daejeon, Korea, which provides the fabrication of small size circuit comparable to conventional MMIC and at drastically low cost due to the use of aluminum as a wafer. The advantage of low cost is especially promising for RF components fabrication in commercial applications like mobile communications. The fabricated power amplifier has a compact size of 4.4 × 4.4mm² and shows power added efficiency (PAE) of about 35% and harmonic suppression of above 30dBc for second and third harmonics at an output power of 39dBm.

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This paper proposes a low-phase-noise ring-VCO-based frequency multiplier with a new subharmonic direct injection locking technique that only uses a time-delay cell and four MOS transistors. Since the proposed technique behaves as an exclusive OR and can double the reference signal frequency, it increases phase correction points and achieves low phase noise characteristic across the wide output frequency range. The frequency multiplier was fabricated by using 65nm Si CMOS process. Measured 1-MHz-offset phase noise at 6.34GHz with reference signals of 528MHz was -119dBc/Hz.

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A 60GHz direct conversion transceiver which employs amplitude/phase imbalance cancellation technique is newly proposed. By using the proposed technique, the receive path of the transceiver achieves less than 0.2dB of amplitude error and less than 3^° of phase error at 60GHz bands over a 10GHz bandwidth, which relaxes the design accuracy required for baluns used in the transceiver. It also employs a simple and fast calibration algorithm to adjust the locking range of the divide-by-3 injection locked divider in the phase locked loop. Fabricated in 90nm CMOS technology, the transceiver achieves a low power consumption of 230mW in transmit mode and 173mW in receive mode. The output spectrum of 1.76Gsps π/2-BPSK/QPSK modulation shows the excellent distortion and spurious suppression that meet the IEEE802.11ad draft standard.

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Microwave interconnects have been proposed recently to break-down long wires in large integrated circuits. In this paper, using of coplanar waveguide RF interconnects in FPGAs is explored to improve performance and reduce routing congestion. We propose a new FPGA architecture consisting of both metal wires and RF receivers/transmitters corresponding with an algorithm to route the proposed FPGA. Experimental results show that used routing tracks and routing congestion are reduced by 23.8% and 7.06%, respectively and performance of the attempted benchmarks is improved by about 33% using this technique. These benefits are earned in reasonable cost of area and power consumption which is negligible for large and complex circuits.

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Single front-end architecture with parasitic antenna element (PAE) in compact array system has been proposed for enhancing spectral efficiency and miniaturizing the receiver. Although most of studies paid attention to design optimal receiver with antenna mutual coupling on fading correlation, relatively little attention has been paid to noise. In this paper, we propose a low noise model for single front-end MIMO receiver system with PAE which includes arbitrary signal and noise coupling. The proposed model articulates physical noise sources and relates their spatial correlation with array receive antennas, parasitic element, front-end and matching circuit. A matching circuit is designed to achieve minimum noise figure. After that, the optimal PAE value is derived to maximize channel capacity. We present numerical analysis to verify the proposed system on certain conditions.

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In order to improve the detection performance in passive millimeter-wave (PMMW) imaging, a new method forwarding a null in the direction of human body and objects is proposed. The forward-nulling PMMW imaging using a dielectric tube occupied by cooling water placed near the focus line of a parabolic cylinder are performed. It is shown experimentally that the contrast between human body and conducting objects such as a conducting plate and a conducting sphere is improved by the presence of the cooling dielectric tube and parabolic cylinder.

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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 ε_r =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 3dB-down gain bandwidth has also been increased from 1.3GHz to 2.3GHz.

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In this paper, effects of the parasite elements on an antenna impedance of a UHF RFID tag put on a high impedance surface (HIS) are experimentally studied in detail. It is shown that small parasite elements on a mushroom HIS structure can help to recover a mismatch of the impedance and this impedance recovery is brought by an in-phase frequency shift of the HIS due to a mutual coupling between the HIS and the parasite elements. The technique is applied to a commercial 953MHz band RFID tag inlet antenna on a 5×3-cell HIS with the total dimension of 125×75×1.5mm³ and it is demonstrated that the impedance mismatch is successfully recovered and the tag operates with a reading range of 3m even on a 200×300×2mm³ aluminum plate.

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The left-handed (LH) operation of a three-dimensional (3-D) LH material composed of wired metallic spheres is experimentally confirmed. A 15×15×3-cell periodic structure designed to have an isotropic LH characteristics is fabricated by a 3-D printer with post plating technology, and near-field measurements of refracted waves by the negative refractive index slab lens are carried out. The dispersion characteristics measured from the near-field distributions on the surface of the LH material clearly show that the structure supports the backward waves at 12GHz band. It is also shown experimentally that the resolution of the slab lens exceeds the diffraction limit by near field measurements with a single source and adjacent two sources. In addition, near-field measurements from the LH material near the Γ-point frequency at 12.90GHz are carried out. A highly directive plane wave with a single point source is observed and the near-zero-index operation has been confirmed.

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A left-handed material with simple structure is proposed. The material is composed of periodic metal strips exhibiting both electric property and magnetic property. The dispersion relations and the transmission characteristics are confirmed experimentally. The main field pattern of guided mode in the material is similar to that of the plane wave, and a transmission characteristic with low reflection is obtained for an impedance matching region.

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A can swells due to gas produced from an inner food caused by poor hermetic sealing of the can. This paper presents a measurement for the bottom shape to detect a swelled can by using the millimeter-wave imaging. For get higher spatial resolution and an adjustable focal distance, two collimated beam lenses were applied to the measurement system. First, a configuration of the system was studied with the electrical field intensity and focal distance by using full wave electromagnetic simulation. Next, the bottom shapes of cans with different pressure were evaluated quantitatively using the system. A shape change of 0.5mm was detected with pressure difference of 50kPa, and it is reasonable considering actual dimension of the can shape. A potential of the proposed detection method was presented.

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In this paper, a capacitive-cross-coupling common-gate (CCC-CG) LNA using capacitive feedback is proposed to improve the noise figure (NF). In the conventional CCC-CG LNA, the transconductance g_m is determined by the input-matching condition while a lager g_m is required to improve NF. g_m of the proposed LNA can be increased and NF can be improved by using the added capacitive feedback. The analytical calculation shows that the proposed LNA can perform better than the conventional CCC-CG LNA. In the measurement results using a 0.18-µm CMOS technology, the gain is 10.4-13.4dB, NF is 2.7-2.9dB at 0.8-1.8GHz, and IIP₃ is -7dBm at 0.8GHz. The power consumption is 6.5mW with a 1.8-V supply.

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This paper presents a new 8T (8-transistor) SRAM cell layout mitigating multiple-bit upset (MBU) in a divided wordline structure. Because bitlines along unselected columns are not activated, the divided wordline structure eliminates a half-select problem and achieves low-power operation, which is often preferred for low-power/low-voltage applications. However, the conventional 8T SRAM with the divided wordline structure engenders MBUs because all bits in the same word are physically adjoining. Consequently, it is difficult to apply an error correction coding (ECC) technique to it. In this paper, we propose a new 8T cell layout pattern that separates internal latches in SRAM cells using both an n-well and a p-substrate. We saw that a SEU cross section of nMOS is 3.5-4.5 times higher than that of pMOS (SEU: single event upset; a cross section signifies a sensitive area to soft error effects). By using a soft-error simulator, iRoC TFIT, we confirmed that the proposed 8T cell has better neutron-induced MBU tolerance. The simulator includes soft-error measurement data in a commercial 65-nm process. The MBU in the proposed 8T SRAM is improved by 90.70% and the MBU soft error rate (SER) is decreased to 3.46 FIT at 0.9V when ECC is implemented (FIT: failure in time). Additionally, we conducted Synopsys 3-D TCAD simulation, which indicates that the linear energy transfer (LET) threshold in SEU is also improved by 66% in the proposed 8T SRAM by a common-mode effect.

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Reverse-recovery modeling for p-i-n diodes in the high current-density conditions are discussed. With the dynamic carrier-distribution-based modeling approach, the reverse recovery behaviors are explained in the high current-density conditions, where the nonquasi-static (NQS) behavior of carriers in the drift region is considered. In addition, a specific feature under the high current-density condition is discussed. The proposed model is implemented into a commercial circuit simulator in the Verilog-A language and its reverse recovery modeling ability is verified with a two-dimensional (2D) device simulator, in comparison to the conventional lumped-charge modeling technique.

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Polarization-maintaining photonic crystal fiber couplers (PM-PCFCs) were fabricated using a CO₂ laser irradiation technique. We could control the states of air holes in the tapered region of couplers by adjusting the laser power density in the fusion and the elongation processes. It was demonstrated that the air hole remaining PM-PCFC exhibited polarization-splitting characteristics and that the air hole collapsed PM-PCFC had polarization insensitive coupling characteristics.

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An on-chip soft-start circuit based on a switched-capacitor for DC-DC switching regulator is presented. A ramp-voltage, which is generated by a switched-capacitor, is used to make pulse width slowly increase from zero, in order to eliminate the inrush current and the overshoot voltage during start-up. The post simulation results show that the regulator soft starts well with the proposed soft-start circuit.

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