We report on the spurious suppression effect in low-microwave power transmitters by high temperature superconducting (HTS) bandpass filters (BPFs) which are promising for devices requiring BPFs with high-frequency selectivity. Some of the major issues on the power BPFs with HTS planar circuits for wireless communication applications are reviewed. As a case study for the HTS filter and its spurious suppression effect, this paper describes an example of the measured power spectrum density (PSD) on the suppression effect by one of our developed power BPFs with YBCO films for the 5GHz band. It was designed with equivalent cascade resonators of 16 poles. We demonstrated the effect by HTS power filter in a power amplifier for the 5GHz band.

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We have developed a high-temperature superconducting (HTS) filter with narrow bandwidth characteristic for receiver of weather radar in order to reduce interference between adjacent radar channels. To realize a filter with which a narrow bandwidth and low insertion loss are compatible, resonators with high unloaded Q (Q_u) value are required. Hairpin microstrip resonators with 1.5 times wavelength were adopted to suppress the radiation loss and achieve a high Q_u value. The developed HTS filter has 8-pole quasi-elliptic function response for sharp skirt characteristic. The measured frequency response of the developed filter shows center frequency of 5370MHz, insertion loss of 2.04dB and maximum return loss of 15dB, which agrees with the designed responses.

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The superconducting band-pass filter has small insertion loss and excellent out-of-band rejection properties. It has been put to practical use in a number of applications. However, in order to expand its range of application, a tuning technique that can restore the filter characteristics is needed. We propose an automatic tuning system using a trimming library and checked the feasibility of the system by tuning a forward-coupled filter with three resonators. The results show that the trimming library method is an effective way of automatically improving the filter characteristics.

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We propose a new band selective stop filter construction to decrease the out of band intermodulation distortion (IMD) noise generated in the transmitting power amplifier. Suppression of IMD noise directly improves the adjacent channel leakage power ratio (ACLR). A high-temperature superconducting (HTS) device with extremely high-Q performance with very small hybrid IC pattern would make it possible to implement the proposed filter construction as a practical device. To confirm the effectiveness of the HTS reaction-type filter (HTS-RTF) in improving ACLR, investigations based on both experiments and numerical analyses are carried out. The structure of a 5-GHz split open-ring resonator is investigated; its targets include high-unload Q-factor, low current densities, and low radiation. A designed 5-GHz HTS-RTF with 4MHz suppression bandwidth and more than 40dB MHz^-1 sharp skirt is fabricated and experimentally investigated. The measured ACLR values are improved by a maximum of 12.8dB and are constant up to the passband signal power of 40dBm. In addition, to examine the power efficiency improvement offered by noise suppression of the HTS-RTF, numerical analyses based on measured results of gallium nitride HEMT power amplifier characteristics are conducted. The analyzed results shows the drain efficiency of the amplifier can be improved to 44.2% of the amplifier with the filter from the 15.7% of the without filter.

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Liquid-phase detection of biological targets utilizing magnetic marker and superconducting quantum interference device (SQUID) magnetometer is shown. In this method, magnetic markers are coupled to the biological targets, and the binding reaction between them is detected by measuring the magnetic signal from the bound markers. Detection can be done in the liquid phase, i.e., we can detect only the bound markers even in the presence of unbound (free) markers. Since the detection principle is based on the different magnetic properties between the free and bound markers, we clarified the Brownian relaxation of the free markers and the Neel relaxation of the bound markers. Usefulness of the present method is demonstrated from the detection of the biological targets, such as biotin-coated polymer beads, IgE and Candida albicans.

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High-T_c superconducting quantum interference device (SQUID) is an ultra-sensitive magnetic sensor. After the discovery of the high-T_c superconducting materials, the performance of the high-T_c SQUID has been improved and stabilized. One strong candidate for application is a detection system of magnetic foreign matters in industrial products. There is a possibility that ultra-small metallic foreign matter has been accidentally mixed with industrial products such as lithium ion batteries. If this happens, the manufacturer of the product suffers a great loss recalling products. The outer dimension of metallic particles less than 100 micron cannot be detected using X-ray imaging, which is commonly used for the inspection. Therefore a highly sensitive system for small foreign matters is required. We developed detection systems based on high-T_c SQUID for industrial products. We could successfully detect small iron particles of less than 50 micron on a belt conveyer. These detection levels were hard to be achieved using conventional X-ray detection or other methods.

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We have proposed and successfully demonstrated a two step method for localizing defects on an LSI chip. The first step is the same as a conventional laser-SQUID (L-SQUID) imaging where a SQUID and a laser beam are fixed during LSI chip scanning. The second step is a new L-SQUID imaging where a laser beam is stayed at the point, located in the first step results, during SQUID scanning. In the second step, a SQUID size (A_eff) and the distance between the SQUID and the LSI chip (ΔZ) are key factors limiting spatial resolution. In order to improve the spatial resolution, we have developed a micro-SQUID and the vacuum chamber housing both the micro-SQUID and the LSI chip. The A_eff of the micro-SQUID is a thousand of that of a conventional SQUID. The minimum value of ΔZ was successfully reduced to 25µm by setting both the micro-SQUID and an LSI chip in the same vacuum chamber. The spatial resolution in the second step was shown to be 53µm. Demonstration of actual complicated defects localization was succeeded, and this result suggests that the two step localization method is useful for LSI failure analysis.

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The Transition Edge Sensor (TES)-Energy Dispersive Spectrometer (EDS) is an X-ray detector with high-energy resolution (12.8eV). The TES can be mounted to a scanning electron microscope (SEM). The TES-EDS is based on a cryogen-free dilution refrigerator. The high-energy resolution enables analysis of the distribution of various elements in samples under low acceleration voltage (typically under 5keV) by using K-lines of light elements and M lines of heavy elements. For example, the energy of the arsenic L line differs from the magnesium K line by 28eV. When used to analyze the spore of the Pteris vittata L plant, the TES-EDS clearly reveals a different distribution of As and Mg in the micro region of the plant. The TES-EDS with SEM yields detailed information about the distribution of multi-elements in a sample.

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An impedance-isolation technique is proposed for on-chip ESD protection design for radio-frequency (RF) integrated circuits (ICs), which has been successfully verified in a 0.25-µm CMOS process with thick top-layer metal. With the resonance of LC-tank at the operating frequency of the RF circuit, the impedance (especially, the parasitic capacitance) of the ESD protection devices can be isolated from the RF input node of low-noise amplifier (LNA). Therefore, the LNA can be co-designed with the proposed impedance-isolation technique to simultaneously achieve excellent RF performance and high ESD robustness. The power gain (S₂₁-parameter) and noise figure of the ESD protection circuits with the proposed impedance-isolation technique have been experimentally measured and compared to those with the conventional double-diodes ESD protection scheme. The proposed impedance-isolation technique had been demonstrated to be suitable for on-chip ESD protection design for RF ICs.

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In memory design, the issue is smaller size and low power. Most power used in the ROM is consumed in line capacitance such as address lines, word lines, bit lines, and decoder. This paper presents ROM design of a novel HG (Half Grouping) compression method so as to reduce the parasitic capacitance of bit lines and the area of the row decoder for power consumption and chip area reduction. ROM design result of 512 point FFT block shows that the proposed method reduces 40.6% area, 42.12% power, and 37.82% transistor number respectively in comparison with the conventional method. The designed ROM with proposed method is implemented in a 0.35µm CMOS process. It consumes 5.8mW at 100MHz with a single 3.3V power supply.

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The proposed built-in Power-Cut scheme intended for a wide range of dynamically data retaining memories including embedded SoC memories enables the system-level power management to handle SoC on which the several high density and low voltage scalable memory macros are embedded. This scheme handles the deep standby mode in which the SoC memories keep the stored data in the ultra low standby current, and quick recovery to the normal operation mode and precise power management are realized, in addition to the conventional full power-off mode in which the SoC memories stay in the negligibly low standby current but allow the stored data to disappear. The unique feature of the statically or dynamically changeable internal voltages of memory in the deep standby mode brings about much further reduction of the standby current. This scheme will contribute to the further lowering power of the mobile applications requiring larger memory capacity embedded SoC memories.

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Slit-Mura defect is a notorious yield flaw of color filters. In this study, an innovative non-contact in-line optical inspection method is developed to detect low contrast slit Mura through quantitative measurements by a spectrometer. Using the features of either thickness or chromaticity profiles across a slit Mura, a thickness difference from 21nm to 41nm of color filters can be differentiated accurately. Thus, the quality of color filters can be accessed in-line during the manufacturing process TFT-LCDs.

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By use of the shadow theory developed recently, this paper deals with the transverse electric (TE) wave diffraction by a perfectly conductive periodic array of rectangular grooves. A set of equations for scattering factors and mode factors are derived and solved numerically. In terms of the scattering factors, diffraction amplitudes and diffraction efficiencies are calculated and shown in figures. It is demonstrated that diffraction efficiencies become discontinuous at an incident wave number where the incident wave is switched from a propagating wave to an evanescent one, whereas scattering factors and diffraction amplitudes are continuous even at such an incident wave number.

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An improved dual-band design method is presented for the 180° coupler. It uses the non-uniform impedance ring structure for the arbitrary power division and a π-shaped branch for the dual-band operation The increased design freedom offered by the proposed structure helps to extend the useful dual-band operation range.

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This letter proposes a mismatch insensitive switched-capacitor multiply-by-four (4X) amplifier using the voltage addition scheme. The proposed circuit provides 2-times faster speed and about half of silicon area when compared with the cascade of conventional 2X amplifiers. Monte-Carlo simulation results show about 15% gain accuracy improvement over the cascaded 2X- amplifiers.

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A CMOS current-mode companding divider is presented. Currents of both dividend and divisor are compressed into log-domain. Then the logarithm current of divisor is subtracted from the logarithm current of dividend. After expanding the subtraction result, the division function could be achieved. The simulation results indicate that the proposed divider has with good performance at only 1.8V supply voltage.

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