Showing papers in "IEICE Electronics Express in 2012"
TL;DR: This paper proposes a measurement method of photodetector frequency response based on a heterodyne principle that can provide a relatively short traceability chain to optical and electric power standards.
Abstract: We propose a measurement method of photodetector frequency response. This technique is based on a heterodyne principle, where a high-extinction ratio Mach-Zehnder modulator is used to generate a two-tone lightwave as a stimulus signal up to millimeter-wave frequency bands. Our proposing method can provide a relatively short traceability chain to optical and electric power standards.
36 citations
TL;DR: The experimental results obtained under different operating conditions validate the fast switching, unipolar device characteristics, and high temperature operation capability of the developed diamond SBD.
Abstract: Diamond is considered to be the most promising wide band gap semiconductor material for the fabrication of power switching devices with respect to the figure of merit. The authors have developed a high voltage and high current diamond Schottky barrier diode (SBD). This paper evaluates the static and dynamic electrical performance of the developed diamond SBD as a power switching device. The experimental results obtained under different operating conditions validate the fast switching, unipolar device characteristics, and high temperature operation capability of the developed diamond SBD.
35 citations
TL;DR: ReRAM is one of the most promising emergingnonvolatile memories, in which both electronic and electrochemical effects play important roles in the nonvolatile functionalities.
Abstract: We review recent progresses in Resistive Random Access Memory (ReRAM) technologies together with difficult challenges and prospects. ReRAM is one of the most promising emerging nonvolatile memories, in which both electronic and electrochemical effects play important roles in the nonvolatile functionalities. First, a brief historical overview of the research is provided. The technological overview is reported with the epoch-making achievements. Second, the current understanding in terms of the operation mechanism is shown followed by the technical assessment, especially the advantages of ReRAM. Finally, we summarize the challenges facing the ReRAM technology and the prospects.
30 citations
TL;DR: Results show that the SPD technique significantly enhances the spectral efficiency of SAC-OCDMA systems compared to AND as well as modified-AND subtraction detections.
Abstract: This letter presents a single photodiode detection (SPD) as an effective technique for eradicating both multiple-access interference (MAI) and phase-induced intensity noise (PIIN) in spectral amplitude coding optical code-division multiple-access (SAC-OCDMA) systems. Mathematical analysis and simulation experiments are used to investigate the spectral efficiency (SE) of SAC-OCDMA systems utilizing different detection techniques. Results show that the SPD technique significantly enhances the SE compared to AND as well as modified-AND subtraction detections.
26 citations
TL;DR: The measurement results with ideals switches demonstrate the performances of proposed reconfigurable antennas, which can be suitable for future multi-mode wireless communications systems.
Abstract: A kind of reconfigurable wide slot UWB antenna integrated with stepped impedance resonators (SIRs) and ideal switches is presented. The proposed antenna 1 has dual notch band functions which are obtained by using two stepped impedance stub loaded SIRs. The three reconfigurable models are investigated and discussed. The measurement results with ideals switches demonstrate the performances of proposed reconfigurable antennas. The designed reconfigurable antennas can be suitable for future multi-mode wireless communications systems.
21 citations
TL;DR: Emerging new semiconductor non-volatile memories are reviewed and each type of memory is briefly introduced and the possibility of replacing Flash is discussed.
Abstract: In this article, emerging new semiconductor non-volatile memories are reviewed. We are reaching the integration limit of Flash memories and new types of memories replacing Flash have been actively proposed. Each type of memory is briefly introduced and the possibility of replacing Flash is discussed. FeRAMs, MRAMs, and PCRAMs are already in production and the physics behind the operations and reliabilities are well understood. ReRAMs are now approaching to practical use. However, the operation mechanisms of the other memories have not been understood perfectly. Therefore, it is not fruitful to compare the superiority of each technology at this moment because some innovative idea might enhance a specific technology that happened from time to time.
21 citations
TL;DR: Simulations showed that the optimum proposed pulse shaping filters provide better performance in PAPR reduction compared to those of the RC filter and other existing filters evaluated in various systems.
Abstract: Peak-to-average power ratio (PAPR) plays an important role in the design of wireless communication systems because a high PAPR decreases the efficiency of the power amplifier. A new family of Nyquist pulses was derived by applying a linear combination between two Nyquist pulses. The proposed Nyquist pulses are utilized for pulse shaping to reduce PAPR. The investigated pulses are characterized by a new design parameter (p), giving an additional degree of freedom to minimize PAPR for a given roll-off factor α. While keeping the same bandwidth, the frequency responses of the proposed filters are unique with different values of the parameter p. Simulations showed that the optimum proposed pulse shaping filters provide better performance in PAPR reduction compared to those of the RC filter and other existing filters evaluated in various systems.
20 citations
TL;DR: A model representing the characteristics of G4FET device in order to perform circuit simulations is proposed based upon the neuro-fuzzy technique whose main strength is that they are universal approximators with the ability to solicit interpretable IF-THEN rules.
Abstract: G4-FET has attracted attention as an emerging device for the future generations of semiconductor industry. This paper is intended to propose a model representing the characteristics of G4FET device in order to perform circuit simulations. The modeling approach is established upon the neuro-fuzzy technique whose main strength is that they are universal approximators with the ability to solicit interpretable IF-THEN rules. The accuracy of the proposed model is verified by HSPICE circuit simulations.
19 citations
TL;DR: An aperture-coupled multi-layer broadband microstrip array antenna with coupling ring slots and modified ring patches with encouraging properties, such as wide impedance bandwidth of 77% for |S11| < -10dB and nearly stable gain is presented.
Abstract: An aperture-coupled multi-layer broadband microstrip array antenna with coupling ring slots and modified ring patches is presented. The structure of the array consists of a 3-dB 180°-phase shifter, two 1-port's and two 2-port's aperture-coupled microstrip antennas. All parts of the array antenna are designed for broadband operation. The array antenna works based on the back coupling to the microstrip line of 2-port aperture-coupled antenna. Simulation results of the array display encouraging properties, such as wide impedance bandwidth of 77% for |S11| < -10dB and nearly stable gain. The maximum gain of the array antenna is almost 12.65dBi at 5GHz. The radiation efficiency, radiation pattern, side-lobe level and cross-polarization are also adequate within the impedance bandwidth between of 3.34 and 7.53GHz.
19 citations
TL;DR: A novel Microstrip Low-Pass Filter using a simple symmetrical U-shaped resonator that has a wide stopband with high attenuation in the stopband and acceptable sharp frequency response is presented.
Abstract: This paper peresents a novel Microstrip Low-Pass Filter (LPF) using a simple symmetrical U-shaped resonator. In this work, a 5.45GHz LPF is developed. The experimental results show that in comparison with other LPFs, it has a wide stopband with high attenuation in the stopband and acceptable sharp frequency response. The insertion-loss is less than 0.1dB and the rejection band over -20dB covers 6.05GHz to 37.35GHz. The measured and simulated results are in good agreement.
19 citations
TL;DR: After determining topology a proposed CAD (Computer Aided Design) with a proposed multi objective genetic algorithm will be used to optimize the high speed hybrid Full Adder with low power consumption.
Abstract: In this paper a new high speed hybrid Full Adder with low power consumption is presented. Furthermore, after determining topology a proposed CAD (Computer Aided Design) with a proposed multi objective genetic algorithm will be used to optimize the high speed hybrid Full Adder. The size of generative Full Adder transistors is introduced to algorithm as the inputs and the average power consumption and max delay are introduced as the outputs. After performing the algorithm, several results will be obtained as they have no priority to each other, so designer can select whichever according to his need. Simulation results show that, proposed structure uses less average power. Algorithm program is written in MATLAB and the circuit simulated by Hspice with 0.18 technology.
TL;DR: A radiation hardened resistive SRAM structure (rSRAM) is proposed for the SRAM-based FPGAs in this paper and can tolerate simultaneous disruptions affecting all sensitive nodes with an LET (Liner Energy Transfer) of 100Mev-cm2/mg.
Abstract: A radiation hardened resistive SRAM structure (rSRAM) is proposed for the SRAM-based FPGAs in this paper. The rSRAM extends the conventional 6T SRAM structure by connecting memristors between the information nodes and drains of the transistors which compose cross-coupled invertors. With memristors connected to drains of OFF transistors configured to high resistance state while others configured to low resistance state forming stable voltage dividing path, the rSRAM structure is immune to both multiple-node upsets and multiplebit upsets (MBUs). The simulation result demonstrates that rSRAM cell can tolerate simultaneous disruptions affecting all sensitive nodes with an LET (Liner Energy Transfer) of 100Mev-cm2/mg.
TL;DR: A multiple-supply-voltages aware high-level synthesis algorithm for HDR architectures which realizes high-speed and high-efficient circuits and obtains a solution which cannot be obtained by the original algorithm even if a very tight clock constraint is given.
Abstract: In this paper, we propose multiple-supply-voltages aware high-level synthesis algorithm for HDR architectures which realizes high-speed and high-efficient circuits. We propose three new techniques: virtual area estimation, virtual area adaptation, and floorplanning-directed huddling, and integrate them into our HDR architecture synthesis algorithm. Virtual area estimation/adaptation effectively estimates a huddle area by gradually reducing it during iterations, which improves the convergence of our algorithm. Floorplanningdirected huddling determines huddle composition very effectively by performing floorplanning and functional unit assignment inside huddles simultaneously. Experimental results show that our algorithm achieves about 29% run-time-saving compared with the conventional algorithms, and obtains a solution which cannot be obtained by our original algorithm even if a very tight clock constraint is given.
TL;DR: A hybrid neural model is proposed for the SOC estimation of ZEBRA (Zero Emission Battery Research Activities) battery considering the aging effect through the state of health (SOH) and the discharge efficiency (DE) parameters.
Abstract: The state of charge (SOC) estimation for electric vehicles (EVs) is important and helps to optimize the utilization of the battery energy storage in EVs. In this way, aging is also a key parameter impacting the performance of batteries. In this paper, a hybrid neural model is proposed for the SOC estimation of ZEBRA (Zero Emission Battery Research Activities) battery considering the aging effect through the state of health (SOH) and the discharge efficiency (DE) parameters. The number of hidden nodes in neural modules is also optimized using particle swarm optimization (PSO) algorithm. The SOC estimation error of the proposed system is 1.7% when compared with the real SOC obtained from a discharge test.
TL;DR: The use of particle swarm optimization (PSO) algorithm as a prominent technique is proposed to optimize the weighting coefficients vector to improve detection performance of the soft-decision fusion- (SDF-) based cooperative spectrum sensing.
Abstract: In soft-decision fusion- (SDF-) based cooperative spectrum sensing, weighting the coefficients vector is the main factor affecting the detection performance of cognitive radio networks. In this paper, the use of particle swarm optimization (PSO) algorithm as a prominent technique is proposed to optimize the weighting coefficients vector. The proposed PSO-based scheme opts for the best weighting coefficients vector, leading to improved detection performance of the system. The performance of the proposed method is analyzed and compared with genetic algorithm- (GA-) based technique as well as other conventional SDF schemes through computer simulations. Simulation results validate the robustness of the proposed method over all other SDF techniques.
TL;DR: A cognitive radio antenna integrated with narrow /ultrawide band (UWB) antenna is described in this paper, suitable for cognitive radio applications where the UWB antenna is required for spectrum sensing and the narrow band antenna is used for reconfigurable operation.
Abstract: A cognitive radio antenna integrated with narrow /ultrawide band (UWB) antenna is described in this paper. The proposed antenna consists of two port-fed wide-slot antennas sharing the same substrate. The proposed ultra-wideband (UWB) antenna which covers the entire UWB band from 3.1 GHz to 10.6 GHz is used for channel sensing. The integrated, narrowband wide-slot antenna, operating in the range of 8.2 GHz to 11.0 GHz is designed to communicate with other wireless devices. The reconfigurable function is realized by utilizing ideal switches. The isolation between the two ports is better than −10 dB. The design is suitable for cognitive radio applications where the UWB antenna is required for spectrum sensing and the narrow band antenna is used for reconfigurable operation, which can be tuned over a wide bandwidth by changing the dimensions of the triangular radiation patch using ideal ON/OFF switches.
TL;DR: The proposed state re-ordering technique to increase the efficiency of Vt window utilization in TLC NAND Flash memories provides 12.5~18.4% smaller BER compared to conventional Gray-code mapping.
Abstract: In scaled technologies, large cell-to-cell interference and FN tunneling disturbance degrade threshold voltage (Vt) window which we can place program states. Moreover, in Triple Layer Cell (TLC) NAND Flash we should place seven program states (P1 ~ P7) in the narrow Vt window, incurring large biterror rate (BER). In this paper, we propose a state re-ordering technique to increase the efficiency of Vt window utilization in TLC NAND Flash memories. Our simulation results show that under equivalent Vt window sizes, the proposed technique provides 12.5~18.4% smaller BER compared to conventional Gray-code mapping.
TL;DR: The experimental investigation to increase the sensitivity of an optical fiber refractive index sensor with a multimode interference (MMI) structure is presented and it is confirmed that the interference wavelength can be set in the long-wavelength region by adjusting the sensing-part length.
Abstract: This letter presents the experimental investigation to increase the sensitivity of an optical fiber refractive index sensor with a multimode interference (MMI) structure. It is confirmed that the interference wavelength can be set in the long-wavelength region by adjusting the sensing-part length. Moreover, it is shown that the fineness of the cores in the input and output fibers is essential to obtain a sharp interference signal. We demonstrate the high sensitivity of an MMI-structured optical fiber sensor by applying it to refractive index measurements of ethanol/water solutions. This refractive index sensor reveals a resolution as fine as 1.8 × 10-5, which is the highest value so far reported in this type and has one order higher sensitivity than a commercially available Abbe refractometer (∼ 10-4).
TL;DR: The result shows that the THz intensity has a good linear relation to the emissivity, which means THz emISSivity of an unknown material can be estimated at a room-temperature with the THZ passive imaging system.
Abstract: We have demonstrated terahertz (THz) passive imaging of room-temperature objects using a 4K-cryocooled THz photoconductive detector with background limited infrared performance (BLIP) at around 1.5-2.5THz. Images of a safety razor blade and a coin concealed in a plastic package or an envelope are successfully obtained with spatial resolutions of wavelength order using the THz passive imaging system. We have compared the measured THz intensity of several materials with emissivities calculated using the reported optical constants. The result shows that the THz intensity has a good linear relation to the emissivity, which means THz emissivity of an unknown material can be estimated at a room-temperature with the THz passive imaging system.
TL;DR: Coherent optical two-tone generation using an optical frequency comb generator based on an amplified optical fiber loop is successfully demonstrated and is suitable for high-speed radio communication based on advanced modulation techniques.
Abstract: Coherent optical two-tone generation using an optical frequency comb generator based on an amplified optical fiber loop is successfully demonstrated. The observed phase noises in the 100-GHz band are less than −80 dBc/Hz at 1 MHz. This method is suitable for high-speed radio communication based on advanced modulation techniques.
TL;DR: An improved design of a radiation-hardened static random access memory (SRAM) that is extremely tolerant to logic upset as it does not flip even for a transient pulse with 100 times the critical charge of the ROCK cell.
Abstract: This paper presents an improved design of a radiation-hardened static random access memory (SRAM). The simulation results based on the 0.18µm standard digital CMOS technology show that its static current drops dramatically compared with the WHIT cell, and the write speed is equivalent to that of other cells. The memory cell is extremely tolerant to logic upset as it does not flip even for a transient pulse with 100 times the critical charge of the ROCK cell. According to these features, this novel cell suits high reliability applications, such as aerospace and military.
TL;DR: The reason why the antenna radiates multi-polarization waves and how the antenna is designed in order to utilizing frequencies are explained.
Abstract: A novel spiral antenna that simultaneously radiates circularly and linearly polarized waves is presented. The antenna achieved radiating omnidirectional circularly polarized waves by shaping a spiral antenna as its looks like a cross. Moreover, putting a parasitic element close to it, it succeeded in being utilized as a linear polarization antenna at the same time. This paper explains the reason why the antenna radiates multi-polarization waves and how the antenna is designed in order to utilizing frequencies. Experimental results of return losses, radiation patterns and axial ratios of a prototype antenna are shown for verifying its performance. The antenna can be expected to be used for multifunctional mobile communication devices, because it is a single feed and single layer printable antenna.
TL;DR: This paper realizes a displacement measurement along an approach avoiding supplemented sensors and achieves the switching operation between two coexisting periodic states by a displacement feedback control.
Abstract: Micro-electromechanical resonators substantially exhibit bistable and hysteretic response when nonlinear characteristics appear. Badzey et al. reported that the nonlinear micro-electromechanical resonators can be used as a mechanical 1 bit memory. Based on their results, the authors propose reading and writing operations of the memory device. The reading and writing operations imply a displacement measurement and a switching of two stable periodic vibrations, respectively. In this paper, we realize a displacement measurement along an approach avoiding supplemented sensors. In addition, we achieve the switching operation between two coexisting periodic states by a displacement feedback control.
TL;DR: This paper presents a method to fast verify the authorship through extracting the content of the watermarked lookup tables from a binary bit-file and shows that the verification of authorship has high efficiency.
Abstract: Digital watermarking is an innovative technique for intellectual property protection (IPP) of Field Programmable Gate Array (FPGA) designs. However, many of these techniques usually need manually extract marks from binary bit-files by the FPGA tool or exhaustive search to find out marks in the design, which results in inefficiency of the watermark verification. This paper presents a method to fast verify the authorship through extracting the content of the watermarked lookup tables from a binary bit-file. We demonstrate the proposed method on several Xilinx Virtex-II devices, and experimental results on the watermarked designs from the IWLS 2005 benchmarks show that the verification of authorship has high efficiency.
TL;DR: Fundamental oscillations up to 1.08THz with the output power of 5.5 microwatts was achieved in GaInAs/AlAs resonant tunneling diodes (RTDs) at room temperature with the graded emitter, thin barriers, and high-indium-composition transit layers introduced to reduce the tunneling and transit delays.
Abstract: Fundamental oscillations up to 1.08THz with the output power of 5.5 microwatts was achieved in GaInAs/AlAs resonant tunneling diodes (RTDs) at room temperature. The graded emitter, thin barriers, and high-indium-composition transit layers were introduced to reduce the tunneling and transit delays. The first two of these structures are the same as those in RTDs oscillating at 1.04THz reported recently, and the last structure provided for further reduction of the transit time and increase in frequency due to suppression of the Γ-L transition and increment of the launching velocity.
TL;DR: A low-complexity high-performance wearleveling algorithm which named sequential garbage collection (SGC) for flash memory system design is presented and results show that the maximum block erase count and standard deviation of the block erased count compared to the greedy algorithm are decreased.
Abstract: In this paper, a low-complexity high-performance wearleveling algorithm which named sequential garbage collection (SGC) for flash memory system design is presented. The proposed SGC outperforms existing designs in terms of wear evenness and low design complexity. The lifetime of the flash memory can be greatly lengthened by the proposed SGC. The proposed SGC doesn’t require any tuning threshold parameter, and thus it can be applied to various systems without prior knowledge of the system environment for threshold tuning. Simulation results show that the maximum block erase count and standard deviation of the block erase count compared to the greedy algorithm are decreased by up to 75% and 94%, respectively.
TL;DR: A tunable metamaterial absorbers comprised of a new combination shaped metal elements printed on a dielectric substrate loaded with PIN diodes were demonstrated and the reflectivity characteristics of the structure can be varied over the entire 2–18GHz range.
Abstract: A tunable metamaterial absorbers (MA) comprised of a new combination shaped metal elements printed on a dielectric substrate loaded with PIN diodes were demonstrated. Through biasing at different voltages to control the diodes, the reflectivity characteristics of the structure can be varied over the entire 2–18GHz range. A qualitative analysis by a simple visualization method is carried out on the parameters of the tunable MA. Both numerical calculations and microwave measurements have verified the performance.