Showing papers in "IEICE Transactions on Electronics in 2012"
40 citations
TL;DR: A novel microstrip hairpin-line bandpass filter which employs a modified Minkowski fractal shape is proposed and fabricated and measured results are in good agreement with measured results.
Abstract: In this paper, a novel microstrip hairpin-line bandpass filter which employs a modified Minkowski fractal shape is proposed. Although conventional hairpin-line filters are popular for RF front ends, they suffer from undesired spurious responses located at the second harmonic, which causes asymmetry in the upper skirt band. By proper design, the second harmonic of fractal filters can be significantly suppressed through the use of fractal shape. To validate this novel geometry, the proposed filters are fabricated and measured. Simulated results are in good agreement with measured results.
35 citations
TL;DR: The present status of superconducting terahertz emitter using the intrinsic Josephson junctions in high-Tc superconductor Bi2Sr2CaCu2O8+δ is reviewed and fabrication techniques by an Argon ion milling with photolithography or metal masks and by a focused ion beam are described.
Abstract: The present status of superconducting terahertz emitter using the intrinsic Josephson junctions in high-Tc superconductor Bi2Sr2CaCu2O8+δ is reviewed. Fabrication methods of the emitting device, electrical and optical characteristics of them, synchronizing operation of two emitters and an example of applications to the terahertz imaging will be discussed. After the description of fabrication techniques by an Argon ion milling with photolithography or metal masks and by a focused ion beam, optical properties of radiation spectra, the line width, polarization and the spatial distribution of emission are presented with some discussion on the operation mechanism. For electrical properties, reversible and irreversible operations at high and low electrical currents, respectively, and electrical modulation of the radiation intensity for terahertz imaging are presented.
25 citations
TL;DR: An accurate and non-parametric imaging algorithm for targets buried in a homogeneous dielectric medium by advancing the RPM (Range Points Migration) algorithm to internal imaging issues is proposed, which has been demonstrated to provide an accurate image even for complex-shaped objects in free-space measurement.
Abstract: Ultra-wide band (UWB) pulse radar with high range resolution and dielectric permeability is promising as an internal imaging technique for non-destructive testing or breast cancer detection. Various imaging algorithms for buried objects within a dielectric medium have been proposed, such as aperture synthesis, the time reversal approach and the space-time beamforming algorithm. However, these algorithms mostly require a priori knowledge of the dielectric medium boundary in image focusing, and often suffer from inadequate accuracy to identify the detailed structure of buried targets, such as an edge or specular surface owing to employing the waveform focusing scheme. To overcome these difficulties, this paper proposes an accurate and non-parametric (i.e. using an arbitrary shape without target modeling) imaging algorithm for targets buried in a homogeneous dielectric medium by advancing the RPM (Range Points Migration) algorithm to internal imaging issues, which has been demonstrated to provide an accurate image even for complex-shaped objects in free-space measurement. Numerical simulations, including those for two-dimensional (2-D) and three-dimensional (3-D) cases, verify that the proposed algorithm enhances the imaging accuracy by less than 1/10 of the wavelength and significantly reduces the computational cost by specifying boundary extraction compared with the conventional SAR-based algorithm. key words: UWB radars, non-destructive testing, RPM, accurate internal imaging
24 citations
TL;DR: 524,288 NbN-based Josephson junctions were integrated to produce a programmable Josephson voltage standard (PJVS), designed to generate the maximum output voltage of 17V because it was difficult to avoid a reduction of the output voltage due to defects.
Abstract: 524,288 NbN-based Josephson junctions were integrated to produce a programmable Josephson voltage standard (PJVS) on a die of 15mm × 15mm, and the PJVS circuit was cooled to 10K using a cryocooler and operated with a current margin of about 1.0mA. Although an output voltage of 10V was required for a voltage standard, the circuit was designed to generate the maximum output voltage of 17V because it was difficult to avoid a reduction of the output voltage due to defects. Although a perfect chip without any defect was rarely fabricated, the high voltage chip that generated at least 10V was fabricated with the fabrication yield of larger than 30%. The fabrication yield was also improved by optimizing the film growth conditions to reduce the film stress and the number of particles. Applications for a secondary voltage standard and an ac Josephson voltage standard are also described.
23 citations
20 citations
TL;DR: Photonic crystal nanolaser sensor is demonstrated, which detects the adsorption of biomolecules from the lasing wavelength shift and achieves a super-sensitivity in protein sensing whose detection limit is three orders of magnitude lower than that of standard surface-plasmon-resonance sensors.
Abstract: High-performance and low-cost sensors are critical devices for high-throughput analyses of bio-samples in medical diagnoses and life sciences. In this paper, we demonstrate photonic crystal nanolaser sensor, which detects the adsorption of biomolecules from the lasing wavelength shift. It is a promising device, which balances a high sensitivity, high resolution, small size, easy integration, simple setup and low cost. In particular with a nanoslot structure, it achieves a super-sensitivity in protein sensing whose detection limit is three orders of magnitude lower than that of standard surface-plasmon-resonance sensors. Our investigations indicate that the nanoslot acts as a protein condenser powered by the optical gradient force, which arises from the strong localization of laser mode in the nanoslot.
17 citations
15 citations
TL;DR: A novel high speed 4-2 compressor using static and pass-transistor logic, has been designed in a 0.35µm CMOS technology in order to reduce gate level delay and increase the speed.
Abstract: A novel high speed 4-2 compressor using static and pass-transistor logic, has been designed in a 0.35µm CMOS technology. In order to reduce gate level delay and increase the speed, some changes are performed in truth table of conventional 4-2 compressor which leaded to the simplification of logic function for all parameters. Therefore, power dissipation is decreased. In addition, because of similar paths from all inputs to the outputs, the delays are the same. So there will be no need for extra buffers in low latency paths to equalize the delays.
15 citations
TL;DR: DC and RF performance of A1GaNchannel HEMTs fabricated on an A1N substrate is presented and the maximum drain current and the current gain cutoff frequency measured at temperatures from RT to 300°C are compared between devices with an AIGaN channel and a GaN channel.
Abstract: properties of AIGaN-channel HEMT fabricated on a free-standing A1N substrate, estimated at temperatures between 25 and 300°C. The AIGaNchannel HEMT exhibited significantly reduced temperature dependence in DC and RF device characteristics, as compared to those for the conventional A1GaN/GaN HEMT, resulting in larger values in both saturated drain current and current gain cutoff frequency at 300°C. Delay time analyses suggested that the temperature dependence of the AIGaN-channel HEMT was primarily dominated by the effective electron velocity in the A1GaN channel. These results indicate that an A1GaN-channel HEMT fabricated on an AIN substrate is promising for high-performance device applications at high temperatures. key words: AlGaN channel, high temperature, HEMT was still larger for the conventional A1GaN/GaN HEMT than that for the A1GaN-channel device, and no data have been reported on the high-temperature RF performance for the AlGaN-channel HEMT. In this paper, DC and RF performance of A1GaNchannel HEMTs fabricated on an A1N substrate is presented. The maximum drain current and the current gain cutoff frequency measured at temperatures from RT to 300°C are compared between devices with an AIGaN channel and a GaN channel. The mechanism responsible for the superior performance for the developed A1GaN-channel HEMT at high temperatures is discussed.
15 citations
TL;DR: High frequency ray-mode coupling analysis has been utilized, and the total diffracted or radiated field in each region is considered as a summation of successive modal radiation contribution due to the original modal excitation by the incident plane wave.
Abstract: Diffraction field by a wide and thick slit on a conducting screen has been analyzed. High frequency ray-mode coupling analysis has been utilized, and the total diffracted or radiated field in each region is considered as a summation of successive modal radiation contribution due to the original modal excitation by the incident plane wave. Our derived results are compared with those obtained by other solutions, and good agreement has been observed, and the validity of our formulation is confirmed.
TL;DR: 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 and in a onedimensional slot array.
Abstract: 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 er =66 and tanδ =0013 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 onedimensional 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 13 GHz to 23 GHz key words: waveguide, LTCC, loss, slot array, long-line effect millimeterwave
TL;DR: In this article, the Kobayashi potential in electromagnetic theory is reviewed and two problems, diffraction of plane wave by disk and rectangular plate of perfect conductor, are considered, and the present method can be used as reference solutions of the related problems.
Abstract: The Kobayashi potential in electromagnetic theory is reviewed. As an illustration we consider two problems, diffraction of plane wave by disk and rectangular plate of perfect conductor. Some numerical results are compared with approximated and experimental results when they are available to verify the validity of the present method. We think the present method can be used as reference solutions of the related problems.
TL;DR: A Drude-critical points (D-CP) model for considering metal dispersion is newly incorporated into the frequency-dependent FDTD method using the simple trapezoidal recursive convolution (TRC) technique.
Abstract: A Drude-critical points (D-CP) model for considering metal dispersion is newly incorporated into the frequency-dependent FDTD method using the simple trapezoidal recursive convolution (TRC) technique. Numerical accuracy is investigated through the analysis of pulse propagation in a metal (aluminum) cladding waveguide. The TRC technique with a single convolution integral is found to provide higher accuracy, when compared with the recursive convolution counterpart. The methodology is also extended to the unconditionally stable FDTD based on the locally one-dimensional scheme for efficient frequency-dependent calculations.
TL;DR: The fabrication process and the properties of superconducting quantum interference devices (SQUIDs) with a multilayer structure and ramp-edge-type JJs are described, and the formation mechanism of the junction barrier is discussed.
Abstract: Recent developments of electronic devices containing Josephson junctions (JJ) with high-Tc superconductors (HTS) are reported. In particular, the fabrication process and the properties of superconducting quantum interference devices (SQUIDs) with a multilayer structure and ramp-edge-type JJs are described. The JJs were fabricated by re-crystallization of an artificially deposited Cu-poor precursory layer. The formation mechanism of the junction barrier is discussed. We have fabricated various types of gradiometers and magnetometers. They have been actually utilized for several application systems, such as a non-destructive evaluation (NDE) system for deep-lying defects in a metallic plate and a reel-to-reel testing system for striated HTS-coated conductors.
TL;DR: A non-contact PIM measurement method is introduced into the standing wave transmission line method and it is shown that PIM has a relation with its source size and position, and is less produced in small sample compared with operating wavelength.
Abstract: A non-contact PIM measurement method is introduced into the standing wave transmission line method. DUT is tested inside the inner conductor of an opened-coaxial line which is excited in standing wave field. The electromagnetic excitation of DUT realizes non-contact measurement and eliminates electrical contacts such as soldering connection. Employment of wire with the resonant length enables low-power testing. It is also shown that PIM has a relation with its source size and position, and is less produced in small sample compared with operating wavelength.
TL;DR: This paper demonstrates a pulse width controlled PLL without using an LPF, which realizes LPF-less as well as quantization noise free operation.
Abstract: SUMMARY This paper demonstrates a pulse width controlled PLL without using an LPF. A pulse width controlled oscillator accepts the PFD output where its pulse width controls the oscillation frequency. In the pulse width controlled oscillator, the input pulse width is converted into soft thermometer code through a time to soft thermometer code converter and the code controls the ring oscillator frequency. By using this scheme, our PLL realizes LPF-less as well as quantization noise free operation. The prototype chip achieves 60 μm × 20 μm layout area using 65 nm CMOS technology along with 1.73 ps rms jitter while consuming 2.81 mW under a 1.2 V supply with 3.125 GHz output frequency.
TL;DR: A novel design scheme appropriately transforms the impedance of a high power transistor to configure a low loss MR-MN, and numerical analyses show quantitative improvement in the loss using the proposed scheme.
Abstract: This paper presents a novel design scheme for a bandswitchable multi-band power amplifier (BS-MPA). A key point of the design scheme is configuring multi-section reconfigurable matching networks (MR-MNs) optimally in terms of low loss matching in multiple frequency bands from 0.7 to 2.5 GHz. The MR-MN consists of several matching sections, each of which has a matching block connected to a transmission line via a switch. Power dissipation at an actual on-state switch results in the insertion loss of the MR-MN and depends on how the impedance is transformed by the MR-MN. The proposed design scheme appropriately transforms the impedance of a high power transistor to configure a low loss MR-MN. Numerical analyses show quantitative improvement in the loss using the proposed scheme. A 9-band 3-stage BS-MPA is newly designed following the proposed scheme and fabricated on a multi-layer low temperature co-fired ceramic substrate for compactness. The BS-MPA achieves a gain of over 30 dB, an output power of greater than 33 dBm and a power added efficiency of over 40% at the supply voltage of 4 V in each operating band. key words: power amplifier, reconfigurable, matching network, multiband, switch
TL;DR: In this paper, an ADPLL which uses a time-to-digital convertor with <0.13rad resolution achieves LO generation at 3GHz with −104dBc/Hz in-band phase noise.
Abstract: An ADPLL which uses a time-to-digital convertor with <0.13rad resolution achieves LO generation at 3GHz with −104dBc/Hz in-band phase noise. The fine and stable resolution is derived by known phase interpolation circuits. It is fabricated in a 65nm CMOS process and the active area is 0.18mm2. keywords: ADPLL, TDC, phase interpolator.
TL;DR: The results indicate that the InN based quantum dot laser is a promising one for the optical communication system.
Abstract: This paper reports on a theoretical study and modeling of a 1.55µm quantum dot heterostructure laser using InN as a promising candidate for the first time. Details of design and theoretical analysis of probability distribution of the optical transition energy, threshold current density, modal gain, and differential quantum efficiency are presented considering a single layer of quantum dots. Dependence of threshold current density on the RMS value of quantum dot size fluctuations and the cavity length is studied. A low threshold current density of ∼51Acm-2 is achieved at room temperature for a cavity length of 640µm. An external differential efficiency of ∼65% and a modal gain of ∼12.5cm-1 are obtained for the proposed structure. The results indicate that the InN based quantum dot laser is a promising one for the optical communication system.
TL;DR: A novel dual band harmonic-rejection load network, which controls the terminating impedances of the second and third harmonics, and contributes greatly to efficiency improvement of PA, and a matching network which guarantees the high efficiency and gain of PA for the desired dual bands is designed.
Abstract: A class-F high efficiency GaN power amplifier (PA) for dual band operation at 2.14 GHz and 2.35 GHz is proposed. A novel dual band harmonic-rejection load network, which controls the terminating impedances of the second and third harmonics, and contributes greatly to efficiency improvement of PA, is described. In addition, a matching network which guarantees the high efficiency and gain of PA for the desired dual bands is designed. The proposed load network has the harmonic rejection of more than 24 dB which is sufficient for rejecting harmonics, and an insertion loss of less than 0.11 dB. The dual band matching network for the maximum output power results in the measured highest output power for each operating frequency. The fabricated class-F GaN PA has 43 dBm65.4% and 43 dBm-63.9% of output power efficiency at the desired dual frequencies. key words: power amplifier, class-F, dual band
TL;DR: It is concluded that the method of image Green's function works practically even at a critical angle of incidence, and a new image integral equation for the basic surface current, which is solved numerically.
Abstract: This paper deals with the diffraction of a transverse magnetic (TM) plane wave by a perfectly conductive periodic surface by an integral method. However, it is known that a conventional integral method does not work for a critical angle of incidence, because of divergence of a periodic Green's function (integral kernel). To overcome such a divergence difficulty, we introduce an image Green's function which is physically defined as a field radiated from an infinite phased array of dipoles. By use of the image Green's function, it is newly shown that the diffracted field is represented as a sum of radiation from the periodic surface and its image surface. Then, this paper obtains a new image integral equation for the basic surface current, which is solved numerically. A numerical result is illustrated for a very rough sinusoidal surface. Then, it is concluded that the method of image Green's function works practically even at a critical angle of incidence.
TL;DR: The μ-PCD method was found to be a very useful tool not only to evaluate the bulk and the surface states, but also to predict the performance of a-IGZO transistors subjected to various plasma processes in the production.
Abstract: SUMMARY Microwave photoconductivity decay (μ-PCD) method was applied to evaluate the effects of chemical composition and Ar + plasma induced damage on the bulk and the surface states in amorphous In-Ga-ZnO (a-IGZO) films. It was found that the peak reflectivity signal in the photoconductivity response increased with decreasing the Ga content, and had a strong correlation with the a-IGZO transistor performances. In addition, the peak reflectivity signals obtained after various Ar + plasma treatment duration were well correlated with the transistor characteristics. With Ar + plasma treatment, the peak reflectivity signal decreased in accordance with degradation of transistor characteristics. The μ-PCD method was found to be a very useful tool not only to evaluate the bulk and the surface states, but also to predict the performance of a-IGZO transistors subjected to various plasma processes in the production.
TL;DR: Athermal wavelength filters are proposed and realized using Si slot waveguides embedded with benzocyclobutene (BCB) to realize a Si-based optical integrated circuit based on PICs produced by large-scale integration on Si platforms.
Abstract: Photonic integrated circuits (PICs) produced by large-scale integration (LSI) on Si platforms have been intensively researched. Since thermal diffusion from the LSI logic layer is a serious obstacle to realizing a Si-based optical integrated circuit, we have proposed and realized athermal wavelength filters using Si slot waveguides embedded with benzocyclobutene (BCB). First, the athermal conditions were theoretically investigated by controlling the waveguide and gap width of the slot waveguides. In order to introduce the calculated waveguide structures to wavelength filters, the propagation losses and bending losses of the Si slot waveguides were evaluated. The propagation losses were measured to be 5.6 and 5.3dB/cm for slot waveguide widths of 500 and 700nm, respectively. Finally, athermal wavelength filters, a ring resonator, and a Mach-Zhender interferometer (MZI) with a slot waveguide width of 700nm were designed and fabricated. Further, a temperature coefficient of -0.9pm/K for the operating wavelength was achieved with the athermal MZI.