IEICE Transactions on Electronics
Online ISSN : 1745-1353
Print ISSN : 0916-8524
Showing 1-50 articles out of 54 articles from Advance online publication
• Liang CHEN, Dongyi CHEN
Type: PAPER
Article ID: 2020DIP0003
Published: 2020
[Advance publication] Released: August 04, 2020
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Input devices based on direct touch have replaced traditional ones and become the mainstream interactive technology for handheld devices. Although direct touch interaction proves to be easy to use, its problems, e.g. the occlusion problem and the fat finger problem, lower user experience. Camera-based mobile interaction is one of the solutions to overcome the problems. There are two typical interaction styles to generate camera-based pointing interaction for handheld devices: move the device or move an object before the camera. In the first interaction style, there are two approaches to move a cursor's position across the handheld display: move it towards the same direction or the opposite direction which the device moves to. In this paper, the results of a comparison research, which compared the pointing performances of three camera-based pointing techniques, are presented. All pointing techniques utilized input from the rear-facing camera. The results indicate that the interaction style of moving a finger before the camera outperforms the other one in efficiency, accuracy, and throughput. The results also indicate that within the interaction style of moving the device, the cursor positioning style of moving the cursor to the opposite direction is slightly better than the other one in efficiency and throughput. Based on the findings, we suggest giving priority to the interaction style of moving a finger when deploying camera-based pointing techniques on handheld devices. Given that the interaction style of moving the device supports one-handed manipulation, it also worth deploying when one-handed interaction is needed. According to the results, the cursor positioning style of moving the cursor towards the opposite direction which the device moves to may be a better choice.

• K. Watanabe, Y. Kobayashi, Y. Koike
Type: INVITED PAPER
Article ID: 2020DII0004
Published: 2020
[Advance publication] Released: July 22, 2020
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Temperature-independent zero-zero-birefringence polymer (TIZZBP), which exhibits very small birefringence over the wide temperature range, is required to realize real-color images for displays, particularly vehicle-mounted displays. Previously, a TIZZBP was synthesized, but they did not put into practical use because of their too complex composition and low mechanical strength. In this paper, we propose a practical TIZZBP that has high heat resistance, high transparency and sufficient mechanical strength, using a simple binary copolymerization system. Our proposed novel polymer exhibits very low photoelastic birefringence and very low orientational birefringence. Both types of birefringence of this TIZZBP satisfy the negligible levels for displays, which are defined as follows: the absolute values of photoelastic coefficient and intrinsic birefringence are less than 1 × 10-12 Pa-1 and 1 × 10-3, respectively. In addition, temperature dependency of orientational birefringence was very low. Orientational birefringence satisfies the negligible level all over the temperature range from around -40°C to 85°C. This temperature range is important because it is the operational temperature range for vehicle-mounted display. Furthermore, our proposed novel TIZZBP showed high heat resistance, high transparency and sufficient mechanical strength. The glass transition temperature was 194°C. The total light transmittance and the haze value is more than 91% and less than 1%, respectively. The tensile strength of non-oriented films was 35 ∼ 50 MPa. These results suggest our proposed novel TIZZBP has high practicality in addition to very low birefringence. Therefore, this TIZZBP film will be very useful for various displays including vehicle-mounted displays and flexible displays.

• Hiroshi Haga, Takuya Asai, Shin Takeuchi, Harue Sasaki, Hirotsugu Yama ...
Type: INVITED PAPER
Article ID: 2020DII0005
Published: 2020
[Advance publication] Released: July 22, 2020
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We developed an 8.4-inch electrostatic-tactile touch display using a segmented-electrode array (30 × 20) as both tactile pixels and touch sensors. Each pixel can be excited independently so that the electrostatic-tactile touch display allows presenting real localized tactile textures in any shape. A driving scheme in which the tactile strength is independent of the grounding state of the human body by employing two-phased actuation was also proposed and demonstrated. Furthermore, tactile crosstalk was investigated to find it was due to the voltage fluctuation in the human body and it was diminished by applying the aforementioned driving scheme.

• Daisuke INOUE, Tomomi MIYAKE, Mitsuhiro SUGIMOTO
Type: INVITED PAPER
Article ID: 2020DII0002
Published: 2020
[Advance publication] Released: July 21, 2020
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Although transmittance changes like a quadratic function due to the DC offset voltage in FFS mode LCD, its bottom position and flicker minimum DC offset voltage varies depending on the gray level due to the flexoelectric effect. We demonstrated how the influence of the flexoelectric effect changes depending on the electrode width or black matrix position.

• Daisaku Mukaiyama, Masayoshi Yamamoto
Type: PAPER
Article ID: 2020ECP5009
Published: 2020
[Advance publication] Released: July 14, 2020
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Aluminum Electrolytic Capacitors are widely used as the smoothing capacitors in power converter circuits. Recently, there are a lot of studies to detect the residual life of the smoothing Aluminum Electrolytic Capacitors from the information of the operational circuit, such as the ripple voltage and the ripple current of the smoothing capacitor. To develop this kind of technology, more precise impedance models of Aluminum Electrolytic Capacitors become desired. In the case of the low-temperature operation of the power converters, e.g., photovoltaic inverters, the impedance of the smoothing Aluminum Electrolytic Capacitor is the key to avoid the switching element failure due to the switching surge. In this paper, we introduce the impedance calculation model of Aluminum Electrolytic Capacitors, which provides accurate impedance values in wide temperature and frequency ranges.

• Koichi NARAHARA, Koichi MAEZAWA
Type: BRIEF PAPER
Article ID: 2020ECS6012
Published: 2020
[Advance publication] Released: July 14, 2020
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The transition dynamics of a multistable tunnel-diode oscillator is characterized for modulating amplitude of outputted oscillatory signal. The base oscillator possesses fixed-point and limit-cycle stable points for a unique bias voltage. Switching these two stable points by external signal can render an efficient method for modulation of output amplitude. The time required for state transition is expected to be dominated by the aftereffect of the limiting point. However, it is found that its influence decreases exponentially with respect to the amplitude of external signal. Herein, we first describe numerically the pulse generation scheme with the transition dynamics of the oscillator and then validate it with several time-domain measurements using a test circuit.

• Hajime Tanaka, Tsutomu Ishikawa, Takashi Kitamura, Masataka Watanabe, ...
Type: PAPER
Article ID: 2019OCP0005
Published: 2020
[Advance publication] Released: July 10, 2020
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We fabricated an InP-based dual-polarization In-phase and Quadrature (DP-IQ) modulator consisting of a Mach-Zehnder (MZ) modulator array integrated with RF termination resistors and backside via holes for high-bandwidth coherent driver modulators and revealed its high reliability. These integrations allowed the chip size (Chip size: 4.4 mm × 3 mm) to be reduced by 59% compared with the previous chip without these integrations, that is, the previous chip needed 8 chip-resistors for terminating RF signals and 12 RF electrode pads for the electrical connection with these resistors in a Signal-Ground-Signal configuration. This MZ modulator exhibited a 3-dB bandwidth of around 40 GHz as its electrical/optical response, which is sufficient for over 400 Gbit/s coherent transmission systems using 16-ary quadrature amplitude modulation (QAM) and 64QAM signals. Also, we investigated a rapid degradation which affects the reliability of InP-based DP-IQ modulators. This rapid degradation we called optical damage is caused by strong incident light power and a high reverse bias voltage condition at the entrance of an electrode in each arm of the MZ modulators. This rapid degradation makes it difficult to estimate the lifetime of the chip using an accelerated aging test, because the value of the breakdown voltage which induces optical damage varies considerably depending on conditions, such as light power, operation wavelength, and chip temperature. Therefore, we opted for the step stress test method to investigate the lifetime of the chip. As a result, we confirmed that optical damage occurred when photo-current density at the entrance of an electrode exceeded threshold current density and demonstrated that InP-based modulators did not degrade unless operation conditions reached threshold current density. This threshold current density was independent of incident light power, operation wavelength and chip temperature.

• Kiwon Lee, Yongsik Jeong
Type: BRIEF PAPER
Article ID: 2020ECS6003
Published: 2020
[Advance publication] Released: July 09, 2020
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In this paper, a compact microwave push-push oscillator based on a resonant tunneling diode (RTD) has been fabricated and demonstrated. A symmetrical spiral inductor structure has been used in order to reduce a chip area. The designed symmetric inductor is integrated into the InP-based RTD monolithic microwave integrated circuit (MMIC) technology. The circuit occupies a compact active area of 0.088 mm2 by employing symmetric inductor. The fabricated RTD oscillator shows an extremely low DC power consumption of 87 μW at an applied voltage of 0.47 V with good figure-of-merit (FOM) of -191 dBc/Hz at an oscillation frequency of 27 GHz. This is the first implementation as the RTD push-push oscillator with the symmetrical spiral inductor.

• Yuta KANEKO, Junya SEKIKAWA
Type: PAPER
Article ID: 2020EMP0001
Published: 2020
[Advance publication] Released: July 03, 2020
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Silver electrical contacts were separated at constant opening speed in a 200V-500VDC/10A resistive circuit. Break arcs were extinguished by magnetic blowing-out with transverse magnetic field of a permanent magnet. The permanent magnet was appropriately located to simplify the lengthened shape of the break arcs. Magnetic flux density of the transverse magnetic field was varied from 20 to 140mT. Images of the break arcs were observed from the horizontal and vertical directions using two high speed cameras simultaneously. Arc length just before extinction was analyzed from the observed images. It was shown that shapes of the break arcs were simple enough to trace the most part of paths of the break arcs for all experimental conditions owing to simplification of the shapes of the break arcs by appropriate arrangement of the magnet. The arc length increased with increasing supply voltage and decreased with increasing magnetic flux density. These results will be discussed in the view points of arc lengthening time and arc lengthening velocity.

• Yoshiki KAYANO, Kazuaki MIYANAGA, Hiroshi INOUE
Type: BRIEF PAPER
Article ID: 2020EMS0002
Published: 2020
[Advance publication] Released: July 03, 2020
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In the design of electrical contacts, it is required to pursue a solution which satisfies simultaneously multi-objective (electrical, mechanical, and thermal) performances including conflicting requirements. Preference Set-Based Design (PSD) has been proposed as practical procedure of the fuzzy set-based design method. This brief paper newly attempts to propose a concurrent design method by PSD to electrical contact, specifically a design of a shape of cantilever in relay contacts. In order to reduce the calculation (and/or experimental) cost, this paper newly attempt to apply Design of Experiments (DoE) for meta-modeling to PSD. The number of the calculation for the meta-modeling can be reduced to $\frac{1}{729}$ by using DoE. The design parameters (width and length) of a cantilever for drive an electrical contact, which satisfy required performance (target deflection), are obtained in ranges successfully by PSD. The validity of the design parameters is demonstrated by numerical modeling.

• Masahiro TANAKA
Type: PAPER
Article ID: 2020ECP5004
Published: 2020
[Advance publication] Released: June 22, 2020
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New boundary integral equations are proposed for two-port slab waveguides which satisfy single mode condition. The boundary integral equations are combined with the orthogonality of guided mode and non-guided field. They are solved by the standard boundary element method with no use of mode expansion technique. Reflection and transmission coefficients of guided mode are directly determined by the boundary element method. To validate the proposed method, step waveguides for TE wave incidence and triangular rib waveguides for TM wave incidence are investigated by numerical calculations.

• Ken'ichi Hosoya, Ryosuke Emura
Type: PAPER
Article ID: 2020ECP5016
Published: 2020
[Advance publication] Released: June 22, 2020
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An ƒ0/2ƒ0 (frequency ratio of two) microstrip diplexer with simple circuit configuration as well as low and wideband insertion-loss characteristics is proposed. It is a parallel combination of a coupled line for ƒ0 port and a wave-trap circuit composed of a transmission line and an open stub for 2ƒ0 port. All the lines and stub have a quarter-wave length for ƒ0. Matching circuits are not needed. Circuit and electro-magnetic simulation results prove that the proposed ƒ0/2ƒ0 diplexer exhibits well-balanced properties of insertion loss (IL), IL bandwidth, and isolation, as compared to conventional simple ƒ0/2ƒ0 diplexers composed of two wave-trap circuits or two coupled lines. The proposed diplexer is fabricated on a resin substrate in a microstrip configuration at frequencies of ƒ0/2ƒ0 = 2.5/5 GHz. Measured results are in good agreement with simulations and support the above conclusion. The proposed diplexer exhibits ILs of 0.46/0.56 dB with 47/47 % relative bandwidth (for ƒ0/2ƒ0), which are lower and wider than ƒ0/2ƒ0 diplexers in literatures at the same frequency bands.

• Yosuke Hinakura, Hiroyuki Arai, Toshihiko Baba
Type: PAPER
Article ID: 2019OCP0004
Published: 2020
[Advance publication] Released: June 15, 2020
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A compact silicon photonic crystal waveguide (PCW) slow-light modulator is presented. The proposed modulator is capable of achieving a 64 Gbps bit-rate in a wide operating spectrum. The slow- light enhances the modulation efficiency in proportion to its group index ng. Two types of 200-μm-long PCW modulators are presented. These are low- and high-dispersion devices, which are implemented using a complementary metal-oxide-insulator process. The lattice-shifted PCW achieved low-dispersion slow-light and exhibited ng ≈ 20 with an operating spectrum Δλ ≈ 20 nm, in which the fluctuation of the extinction ratio is ±0.5 dB. The PCW device without the lattice shift exhibited high-dispersion, for which a large or small value of ng can be set on demand by changing the wavelength. It was found that for a large ng, the frequency response was degraded due to the electro-optic phase mismatch between the RF signals and slow-light even for such small-size modulators. Meander-line electrodes, which bypass and delay the RF signals to compensate for the phase mismatch, are proposed. A high cutoff frequency of 55 GHz was theoretically predicted, whereas the experimentally measured value was 38 GHz. A high-quality open eye pattern for a drive voltage of 1 V at 32 Gbps was observed. The clear eye pattern was maintained for 50-64 Gbps, although the drive voltage increased to 3.5-5.3 V. A preliminary operation of a 2-bits pulse amplitude modulation up to 100 Gbps was also attempted.

• Koichiro SAWA, Yoshitada WATANABE, Takahiro UENO, Hirotasu MASUBUCHI
Type: PAPER
Article ID: 2020EMP0002
Published: 2020
[Advance publication] Released: June 08, 2020
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The authors have been investigating the deterioration process of Au-plated slip-ring and Ag-Pd brush system with lubricant to realize stable and long lifetime. Through the past tests, it can be made clear that lubricant is very important for long lifetime, and a simple model of the deterioration process was proposed. However, it is still an issue how the lubricant is deteriorated and also what the relation between lubricant deterioration and contact voltage behavior is.

In this paper, the contact voltage waveforms were regularly recorded during the test, and analyzed to obtain the time change of peak voltage and standard deviation during one rotation. Based on these results, it is discussed what happens at the interface between ring and brush with the lubricant. And the following results are made clear. The fluctuation of voltage waveforms, especially peaks of pulse-like fluctuation more easily occurs for minus rings than for plus rings. Further, peak values of the pulse-like fluctuation rapidly decreases and disappear at lower rotation speed as mentioned in the previous works. In addition, each peaks of the pulse-like fluctuation is identified at each position of the ring periphery.

From these results, it can be assumed that lubricant film exists between brush and ring surface and electric conduction is realized by tunnel effect. In other words, it can be made clear that the fluctuation would be caused by the lubricant layer, not only by the ring surface. Finally, an electric conduction model is proposed and the above results can be explained by this model.

• Daichi FURUBAYASHI, Yuta KASHIWAGI, Takanori SATO, Tadashi KAWAI, Akir ...
Type: PAPER
Article ID: 2019OCP0002
Published: 2020
[Advance publication] Released: June 05, 2020
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A new structure of the electro-optic modulator to compensate the third-order intermodulation distortion (IMD3) is introduced. The modulator includes two Mach-Zehnder modulators (MZMs) operating with frequency chirp and the two modulated outputs are combined with an adequate phase difference. We revealed by theoretical analysis and numerical calculations that the IMD3 components in the receiver output could be selectively suppressed when the two MZMs operate with chirp parameters of opposite signs to each other. Spectral power of the IMD3 components in the proposed modulator was more than 15 dB lower than that in a normal Mach-Zehnder modulator at modulation index between 0.15π and 0.25π rad. The IMD3 compensation properties of the proposed modulator was experimentally confirmed by using a dual parallel Mach-Zehnder modulator (DPMZM) structure. We designed and fabricated the modulator with the single-chip structure and the single-input operation by integrating with 180° hybrid coupler on the modulator substrate. Modulation signals were applied to each modulation electrode by the 180° hybrid coupler to set the chirp parameters of two MZMs of the DPMZM. The properties of the fabricated modulator were measured by using 10 GHz two-tone signals. The performance of the IMD3 compensation agreed with that in the calculation. It was confirmed that the IMD3 compensation could be realized even by the fabricated modulator structure.

• Toshiya MURAI, Yuya SHOJI, Nobuhiko NISHIYAMA, Tetsuya MIZUMOTO
Type: PAPER
Article ID: 2019OCP0003
Published: 2020
[Advance publication] Released: June 05, 2020
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Magneto-optical (MO) switches operate with a dynamically applied magnetic field. The MO devices presented in this paper consist of microring resonators (MRRs) fabricated on amorphous silicon-on-garnet platform. Two types of MO switches with MRRs were developed. In the first type, the switching state is controlled by an external magnetic field component included in the device. By combination of MO and thermo–optic effects, wavelength tunable operation is possible without any additional heater, and broadband switching is achievable. The other type of switch is a self-holding optical switch integrated with an FeCoB thin-film magnet. The switching state is driven by the remanence of the integrated thin-film magnet, and the state is maintained without any power supply.

• Yoshiki HAYAMA, Katsumi NAKATSUHARA, Shinta UCHIBORI, Takeshi NISHIZAW ...
Type: PAPER
Article ID: 2019OCP0007
Published: 2020
[Advance publication] Released: June 05, 2020
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Horizontal slot waveguides enable light to be strongly confined in thin regions. The strong confinement of light in the slot region offers the advantages of enhancing the interaction of light with matter and providing highly sensitive sensing devices. We theoretically investigated fundamental characteristics of horizontal slot waveguides using Nb2O5. The coupling coefficient between SiO2 slot and air slot waveguides was calculated. Characteristics of bending loss in slot waveguide were also analyzed.

The etching conditions in reactive ion etching needed to obtain a sidewall with high verticality were studied. We propose a process for fabricating horizontal slot waveguides using Nb2O5 thin film deposition and selective etching of SiO2. Horizontal slot waveguides were fabricated that had an SiO2 slot of less than 30 nm SiO2. The propagated light passing through the slot waveguides was also obtained.

• Ai Yanagihara, Keita Yamaguchi, Takashi Goh, Kenya Suzuki
Type: PAPER
Article ID: 2019OCP0008
Published: 2020
[Advance publication] Released: June 05, 2020
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We demonstrated a compact 16 × 16 multicast switch (MCS) made from a silica-based planar lightwave circuit (PLC). The switch utilizes a new electrical connection method based on surface mount technology (SMT). Five electrical connectors are soldered directly to the PLC by using the standard reflow process used for electrical devices. We reduced the chip size to half of one made with conventional wire bonding technology. We obtained satisfactory solder contacts and excellent switching properties. These results indicate that the proposed method is suitable for large-scale optical switches including MCSs, variable optical attenuators, dispersion compensators, and so on.

• Kenji MII, Akihito NAGAHAMA, Hirobumi WATANABE
Type: PAPER
Article ID: 2019CTP0001
Published: 2020
[Advance publication] Released: May 28, 2020
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This paper proposes an ultra-low quiescent current low-dropout regulator (LDO) with a flipped voltage follower (FVF)-based load transient enhanced circuit for wireless sensor network (WSN). Some characteristics of an FVF are low output impedance, low voltage operation, and simple circuit configuration [1]. In this paper, we focus on the characteristics of low output impedance and low quiescent current. A load transient enhanced circuit based on an FVF circuit configuration for an LDO was designed in this study. The proposed LDO, including the new circuit, was fabricated in a 0.6 μm CMOS process. The designed LDO achieved an undershoot of 75 mV under experimental conditions of a large load transient of 100 μA to 10 mA and a current slew rate (SR) of 1 μs. The quiescent current consumed by the LDO at no load operation was 204 nA.

• Yoshiki KAYANO, Yoshio KAMI, Fengchao XIAO
Type: PAPER
Article ID: 2019ESP0010
Published: 2020
[Advance publication] Released: May 27, 2020
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For actual multichannel differential signaling system, the ideal balance or symmetrical topology cannot be established, and hence, an imbalance component is excited. However a theoretical analysis method of evaluating the voltage and current distribution on the differential-paired lines, which allows to anticipate EM radiation at the design stage and to study possible means for suppressing imbalance components, has not been implemented. To provide the basic considerations for electromagnetic (EM) radiation from practical asymmetrical differential-paired lines structure with equi-length routing used in high-speed board design, this paper newly proposes an analytical method for evaluating the voltage and current at any point on differential-paired lines by expressing the differential paired-lines with an equivalent source circuit and an equivalent load circuit. The proposed method can predict S-parameters, distributions of voltage and current and EM radiation with sufficient accuracy. In addition, the proposed method provides enough flexibility for different geometric parameters and can be used to develop physical insights and design guidelines. This study has successfully established a basic method to effectively predict signal integrity and EM interference issues on a differential-paired lines.

• Haisong Jiang, Yasuhiro Hinokuma, Sampad Ghosh, Ryota Kuwahata, Kiichi ...
Type: BRIEF PAPER
Article ID: 2020ECS6002
Published: 2020
[Advance publication] Released: May 25, 2020
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A novel shuffle converter by using 3D waveguide of MCF (multi-core fiber) / SMF (single mode fiber) ribbon fan-in fan-out configuration towards over 1,000 port count optical matrix switch has been proposed. The shuffle converter enables to avoid waveguide crossing section in the optical matrix switch configuration, and the principle device showed sufficient crosstalk of less than -54.2 dB, and insertion loss of 2.1 dB successfully.

• Tetsuya HIROSE, Yuichiro NAKAZAWA
Type: INVITED PAPER
Article ID: 2019CTI0002
Published: 2020
[Advance publication] Released: May 20, 2020
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This paper discusses and elaborates an analytical model of a multi-stage switched-capacitor (SC) voltage boost converter (VBC) for low-voltage and low-power energy harvesting systems, because the output impedance of the VBC, which is derived from the analytical model, plays an important role in the VBC's performance. In our proposed method, we focus on currents flowing into input and output terminals of each stage and model the VBCs using switching frequency f, charge transfer capacitance CF, load capacitance CL, and process dependent parasitic capacitance's parameter k. A comparison between simulated and calculated results showed that our model can estimate the output impedance of the VBC accurately. Our model is useful for comparing the relative merits of different types of multi-stage SC VBCs. Moreover, we demonstrate the performance of a prototype SC VBC and energy harvesting system using the SC VBC to show the effectiveness and feasibility of our proposed design guideline.

• Asuka Maki, Daisuke Miyashita, Shinichi Sasaki, Kengo Nakata, Fumihiko ...
Type: PAPER
Article ID: 2019CTP0007
Published: 2020
[Advance publication] Released: May 15, 2020
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Many studies of deep neural networks have reported inference accelerators for improved energy efficiency. We propose methods for further improving energy efficiency while maintaining recognition accuracy, which were developed by the co-design of a filter-by-filter quantization scheme with variable bit precision and a hardware architecture that fully supports it. Filter-wise quantization reduces the average bit precision of weights, so execution times and energy consumption for inference are reduced in proportion to the total number of computations multiplied by the average bit precision of weights. The hardware utilization is also improved by a bit-parallel architecture suitable for granularly quantized bit precision of weights. We implement the proposed architecture on an FPGA and demonstrate that the execution cycles are reduced to 1/5.3 for ResNet-50 on ImageNet in comparison with a conventional method, while maintaining recognition accuracy.

• Yohei Sobu, Shinsuke Tanaka, Yu Tanaka
Type: PAPER
Article ID: 2019OCP0006
Published: 2020
[Advance publication] Released: May 15, 2020
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Silicon photonics technology is a promising candidate for small form factor transceivers that can be used in data-center applications. This technology has a small footprint, a low fabrication cost, and good temperature immunity. However, its main challenge is due to the high baud rate operation for optical modulators with a low power consumption. This paper investigates an all-Silicon Mach-Zehnder modulator based on the lumped-electrode optical phase shifters. These phase shifters are driven by a complementary metal oxide semiconductor (CMOS) inverter driver to achieve a low power optical transmitter. This architecture improves the power efficiency because an electrical digital-to-analog converter (DAC) and a linear driver are not required. In addition, the current only flows at the time of data transition. For this purpose, we use a PIN-diode phase shifter. These phase shifters have a large capacitance so the driving voltage can be reduced while maintaining an optical phase shift. On the other hand, this study integrates a passive resistance-capacitance (RC) equalizer with a PIN-phase shifter to expand the electro-optic (EO) bandwidth of a modulator. Therefore, the modulation efficiency and the EO bandwidth can be optimized by designing the capacitor of the RC equalizer. This paper reviews the recent progress for the high-speed operation of an all-Si PIN-RC modulator. This study introduces a metal-insulator-metal (MIM) structure for a capacitor with a passive RC equalizer to obtain a wider EO bandwidth. As a result, this investigation achieves an EO bandwidth of 35.7-37 GHz and a 70 Gbaud NRZ operation is confirmed.

• Ryosuke OZAKI, Tomohiro KAGAWA, Tsuneki YAMASAKI
Type: BRIEF PAPER
Article ID: 2019ESS0005
Published: 2020
[Advance publication] Released: May 14, 2020
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In this paper, we analyzed the pulse responses of dispersion medium with periodically conducting strips by using a fast inversion Laplace transform (FILT) method combined with point matching method (PMM) for both the TM and TE cases. Specifically, we investigated the influence of the width and number of the conducting strips on the pulse response and distribution of the electric field.

• Yue GUAN, Takashi OHSAWA
Type: PAPER
Article ID: 2019ECP5046
Published: 2020
[Advance publication] Released: May 13, 2020
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In recent years, deep neural network (DNN) has achieved considerable results on many artificial intelligence tasks, e.g. natural language processing. However, the computation complexity of DNN is extremely high. Furthermore, the performance of traditional von Neumann computing architecture has been slowing down due to the memory wall problem. Processing in memory (PIM), which places computation within memory and reduces the data movement, breaks the memory wall. ReRAM PIM is thought to be a available architecture for DNN accelerators.

In this work, a novel design of ReRAM neuromorphic system is proposed to process DNN fully in array efficiently. The binary ReRAM array is composed of 2T2R storage cells and current mirror sense amplifiers. A dummy BL reference scheme is proposed for reference voltage generation. A binary DNN (BDNN) model is then constructed and optimized on MNIST dataset. The model reaches a validation accuracy of 96.33% and is deployed to the ReRAM PIM system. Co-design model optimization method between hardware device and software algorithm is proposed with the idea of utilizing hardware variance information as uncertainness in optimization procedure. This method is analyzed to achieve feasible hardware design and generalizable model. Deployed with such co-design model, ReRAM array processes DNN with high robustness against fabrication fluctuation.

• Koichi NARAHARA
Type: BRIEF PAPER
Article ID: 2020ECS6001
Published: 2020
[Advance publication] Released: May 12, 2020
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The injection locking properties of rotary dissipative solitons developed in a closed traveling-wave field-effect transistor (TWFET) are examined. A TWFET can support the waveform-invariant propagation of solitary pulses called dissipative solitons (DS) by balancing dispersion, nonlinearity, dissipation, and field-effect transistor gain. Applying sinusoidal signals to the closed TWFET assumes the injection-locked behavior of the rotary DS; the solitons' velocity is autonomously tuned to match the rotation and external frequencies. This study clarifies the qualitative properties of injection-locked DS using numerical and experimental approaches.

• Zejun ZHANG, Yasuhide TSUJI, Masashi EGUCHI, Chun-ping CHEN
Type: BRIEF PAPER
Article ID: 2019ESS0002
Published: 2020
[Advance publication] Released: May 01, 2020
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A compact optical polarization converter (PC) based on slot waveguide has been proposed in this study. Utilizing the high refractive index contrast between a Si waveguide and SiO2 cladding on the silicon-on-insulator platform, the light beam can be strongly confined in a slot waveguide structure. The proposed PC consists of a square waveguide and an L-shape cover waveguide. Since the overall structure is symmetrically distributed along the axis rotated 45-degree from the horizontal direction, the optical axis of this PC lies in the direction with equi-angle from two orthogonally polarized modes of the input and output ends, which leads to a high polarization conversion efficiency (PCE). 3D FDTD simulation results illustrate that a TE-to-TM mode conversion is achieved with a device length of 8.2 μm, and the PCE exceeds 99.8%. The structural tolerance and wavelength dependence of the PC have also been discussed in detail.

• Satomu YASUDA, Yukihisa SUZUKI, Keiji WADA
Type: BRIEF PAPER
Article ID: 2019ESS0004
Published: 2020
[Advance publication] Released: May 01, 2020
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An active gate driver IC generates arbitrary switching waveform is proposed to reduce the switching loss, the voltage overshoot, and the electromagnetic interference (EMI) by optimizing the switching pattern. However, it is hard to find optimal switching pattern because the switching pattern has huge possible combinations. In this paper, the method to estimate the switching loss and the voltage overshoot from the switching pattern with neural network (NN) is proposed. The implemented NN model obtains reasonable learning results for data-sets.

• Yasunori Suzuki, Hiroshi Okazaki, Shoichi Narahashi
Type: PAPER
Article ID: 2020MMP0005
Published: 2020
[Advance publication] Released: May 01, 2020
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This paper presents analysis results of the intermodulation distortion (IMD) components compensation conditions for dual-band feed-forward power amplifier (FFPA) when inputting dual-band signals simultaneously. The signal cancellation loop and distortion cancellation loop of the dual-band FFPA have frequency selective adjustment paths which consist of filter and vector regulator. The filter selects the desired frequency component and suppresses the undesired frequency component in the desired frequency selective adjustment path. The vector regulators repeatedly adjust the amplitude and phase values of the composite components for the desired and suppressed undesired frequency components. In this configuration, the cancellation levels of the signal cancellation loop and distortion cancellation loop are depending on the amplitude and phase errors of the vector regulator. The analysis results show that the amplitude and phase errors of the desired frequency component almost become independent that of the undesired frequency component in a weak non-linearity condition, when the isolation between the desired band and the undesired band given by the filter is more than 40 dB. The amplitude errors of the desired frequency component are dependent on that of the undesired frequency component in a strong non-linear conditions when the isolation level sets as above. A 1-W-class signal cancellation loop and 20-W-class FFPA are fabricated for 1.7-GHz and 2.1-GHz bands simultaneous operation. The experimental results show that the analysis results are suitable in the experimental conditions. From these investigations, the analysis results can provide a commercially available dual-band FFPA. To our best knowledge, this is first analysis results for the dual-band FFPA.

• Takayuki MORI, Jiro IDA, Hiroki ENDO
Type: PAPER
Article ID: 2020ECP5005
Published: 2020
[Advance publication] Released: April 23, 2020
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In this study, the transient characteristics on the super-steep subthreshold slope (SS) of a PN-body tied (PNBT) silicon-on-insulator field-effect transistor (SOI-FET) were investigated using technology computer-aided design and pulse measurements. Carrier charging effects were observed on the super-steep SS PNBT SOI-FET. It was found that the turn-on delay time decreased to nearly zero when the gate overdrive-voltage was set to 0.1-0.15 V. Additionally, optimizing the gate width improved the turn-on delay. This has positive implications for the low speed problems of this device. However, long-term leakage current flows on turn-off. The carrier lifetime affects the leakage current, and the device parameters must be optimized to realize both a high on/off ratio and high-speed operation.

• Yasuaki Isshiki, Dai Suzuki, Ryo Ishida, Kousuke Miyaji
Type: PAPER
Article ID: 2019CTP0003
Published: 2020
[Advance publication] Released: April 22, 2020
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This paper proposes and demonstrates a 65nm CMOS process cascode single-inductor-dual-output (SIDO) boost converter whose outputs are Liion battery and 1V low voltage supply for RF wireless power transfer (WPT) receiver. The 1V power supply is used for internal control circuits to reduce power consumption. In order to withstand 4.2V Li-ion battery output, cascode 2.5V I/O PFETs are used at the power stage. On the other hand, to generate 1V while maintaining 4.2V tolerance at 1V output, cascode 2.5V I/O NFETs output stage is proposed. Measurement results show conversion efficiency of 87% at PIN=7mW, ILOAD=1.6mA and VBAT=4.0V, and 89% at PIN=7.9mW, ILOAD=2.1mA and VBAT=3.4V.

• Khilda AFIFAH, Nicodimus RETDIAN
Type: PAPER
Article ID: 2019CTP0009
Published: 2020
[Advance publication] Released: April 17, 2020
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Hum noise such as power line interference is one of the critical problems in the biomedical signal acquisition. Various techniques have been proposed to suppress power line interference. However, some of the techniques require more components and power consumption. The notch depth in the conventional N-path notch filter circuits needs a higher number of paths and switches off-resistance. It makes the conventional N-path notch filter less of efficiency to suppress hum noise. This work proposed the new N-path notch filter to hum noise suppression in biomedical signal acquisition. The new N-path notch filter achieved notch depth above 40dB with sampling frequency 50Hz and 60Hz. Although the proposed circuits use less number of path and switches off-resistance. The proposed circuit has been verified using artificial ECG signal contaminated by hum noise at frequency 50Hz and 60Hz. The output of N-path notch filter achieved a noise-free signal even if the sampling frequency changes.

• Ping Li, Feng Zhou, Bo Zhao, Maliang Liu, Huaxi Gu
Type: PAPER
Article ID: 2019ECP5050
Published: 2020
[Advance publication] Released: April 17, 2020
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This paper presents a large-angle imaging algorithm based on a dynamic scattering model for inverse synthetic aperture radar (ISAR). In this way, more information can be presented in an ISAR image than an ordinary RD image. The proposed model describes the scattering characteristics of ISAR target varying with different observation angles. Based on this model, feature points in each sub-image of the ISAR targets are extracted and matched using the scale-invariant feature transform (SIFT) and random sample consensus (RANSAC) algorithms. Using these feature points, high-precision rotation angles are obtained via joint estimation, which makes it possible to achieve a large angle imaging using the back-projection algorithm. Simulation results verifies the validity of the proposed method.

• Saki Susa Tanaka, Akira Kitayama, Yukinori Akamine, Hiroshi Kuroda
Type: BRIEF PAPER
Article ID: 2019ECS6016
Published: 2020
[Advance publication] Released: April 17, 2020
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For automotive millimeter radar, a method using a multi-input multi-output (MIMO) array antenna is essential for high angle resolution with module miniaturization. MIMO enables us to extend an antenna array with virtual antennas, and a large antenna array aperture enables high resolution angle estimation. Time division multiplex (TDM) MIMO, which is a method to generate virtual array antennas, makes it easy to design radar system integrated circuits. However, this method leads to two issues in signal processing; the phase error reduces the accuracy of angle estimation of a moving target, and the maximum detectable velocity decreases in inverse proportion to the number of Tx antennas. We analytically derived this phase error and proposed a method to correct the error. Because the phase error of TDM-MIMO is proportional to the target velocity, accurate estimation of the target velocity is an important issue for phase error correction. However, the decrease of the maximum detectable velocity in TDM-MIMO reduces the accuracy of both velocity estimation and angle estimation. To solve these issues, we propose new signal processing for range-velocity estimation for TDM-MIMO radar. By using the feedback result of the estimated direction of arrival (DoA), we can avoid decreasing the maximum detectable velocity. We explain our method with our simulation results.

• Keijiro SUZUKI, Ryotaro KONOIKE, Satoshi SUDA, Hiroyuki MATSUURA, Shu ...
Type: PAPER
Article ID: 2019OCP0001
Published: 2020
[Advance publication] Released: April 17, 2020
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We review our research progress of multi-port optical switches based on the silicon photonics platform. Up to now, the maximum port-count is 32 input ports × 32 output ports, in which transmissions of all paths were demonstrated. The switch topology is path-independent insertion-loss (PILOSS) which consists of an array of 2 × 2 element switches and intersections. The switch presented an average fiber-to-fiber insertion loss of 10.8 dB. Moreover, -20-dB crosstalk bandwidth of 14.2 nm was achieved with output-port-exchanged element switches, and an average polarization-dependent loss (PDL) of 3.2 dB was achieved with a nonduplicated polarization-diversity structure enabled by SiN overpass waveguides. In the 8 × 8 switch, we demonstrated wider than 100-nm bandwidth for less than -30-dB crosstalk with double Mach-Zehnder element switches, and less than 0.5 dB PDL with polarization diversity scheme which consisted of two switch matrices and fiber-type polarization beam splitters. Based on the switch performances described above, we discuss further improvement of switching performances.

• Zheng SUN, Dingxin XU, Hongye HUANG, Zheng LI, Hanli LIU, Bangan LIU, ...
Type: PAPER
Article ID: 2019CTP0005
Published: 2020
[Advance publication] Released: April 15, 2020
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This paper presents a miniaturized transformer-based ultra-low-power (ULP) LC-VCO with embedded supply pushing reduction techniques for IoT applications in 65-nm CMOS process. To reduce the on-chip area, a compact transformer patterned ground shield (PGS) is implemented. The transistors with switchable capacitor banks and associated components are placed underneath the transformer, which further shrinking the on-chip area. To lower the power consumption of VCO, a gm-stacked LC-VCO using the transformer embedded with PGS is proposed. The transformer is designed to provide large inductance to obtain a robust start-up within limited power consumption. Avoiding implementing an off/on-chip Low-dropout regulator (LDO) which requires additional voltage headroom, a low-power supply pushing reduction feedback loop is integrated to mitigate the current variation and thus the oscillation amplitude and frequency can be stabilized. The proposed ULP TF-based LC-VCO achieves phase noise of -114.8 dBc/Hz at 1MHz frequency offset and 16 kHz flicker corner with a 103 μWpower consumption at 2.6 GHz oscillation frequency, which corresponds to a -193 dBc/Hz VCO figure-of-merit (FoM) and only occupies 0.12mm2 on-chip area. The supply pushing is reduced to 2 MHz/V resulting in a -50 dBc spur, while 5MHz sinusoidal ripples with 50mVPP are added on the DC supply.

• Yoshinao MIZUGAKI, Koki YAMAZAKI, Hiroshi SHIMADA
Type: BRIEF PAPER
Article ID: 2020ECS6005
Published: 2020
[Advance publication] Released: April 13, 2020
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Recently, we demonstrated a rapid-single-flux-quantum NOT gate comprising a toggle storage loop. In this paper, we present our design and operation of a NOR gate that is a straightforward extension of the NOT gate by attaching a confluence buffer. Parameter margins wider than ±28% were confirmed in simulation. Functional tests using Nb integrated circuits demonstrated correct NOR operation with a bias margin of ±21%.

• Ryosuke SUGA, Satoshi KURODA, Atsushi KEZUKA
Type: PAPER
Article ID: 2019ESP0006
Published: 2020
[Advance publication] Released: April 10, 2020
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Authors had proposed a hybrid electromagnetic field analysis method suitable for an airport surface so far. In this paper, the hybrid method is validated by measurements by using a 1/50 scale-model of an airport considering several layouts of the buildings and sloping ground. The measured power distributions agreed with the analyzed ones within 5 dB errors excepting null points and the null positions of the distribution is also estimated within one wavelength errors.

• Xiao XU, Tsuyoshi SUGIURA, Toshihiko YOSHIMASU
Type: PAPER
Article ID: 2020MMP0001
Published: 2020
[Advance publication] Released: April 10, 2020
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This paper presents two ultra-low voltage and high performance VCO ICs with two novel transformer-based harmonic tuned tanks. The first proposed harmonic tuned tank effectively shapes the pseudo-square drain-node voltage waveform for close-in phase noise reduction. To compensate the voltage drop caused by the transformer, an improved second tank is proposed. It not only has tuned harmonic impedance but also provides a voltage gain to enlarge the output voltage swing over supply voltage limitation. The VCO with second tank exhibits over 3 dB better phase noise performance in 1/f2 region among all tuning range. The two VCO ICs are designed, fabricated and measured on wafer in 45-nm SOI CMOS technology. With only 0.3 V supply voltage, the proposed two VCO ICs exhibit best phase noise of -123.3 and -127.2 dBc/Hz at 10 MHz offset and related FoMs of -191.7 and -192.2 dBc/Hz, respectively. The frequency tuning ranges of them are from 14.05 to 15.14 GHz and from 14.23 to 15.68 GHz, respectively.

• Yoshinori KUSUDA
Type: INVITED PAPER
Article ID: 2019CTI0001
Published: 2020
[Advance publication] Released: April 09, 2020
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Chopping technique up-modulates amplifier's offset and low-frequency noise up to its switching frequency, and therefore can achieve low offset and low temperature drift. On the other hand, it generates unwanted AC and DC errors due to its switching artifacts such as up-modulated ripple and glitches. This paper summarizes various circuit techniques of reducing such switching artifacts, and then discusses the advantages and disadvantages of each technique. The comparison shows that newer designs with advanced circuit techniques can achieve lower DC and AC errors with higher chopping frequency.

• Yoshihide Komatsu, Akinori Shinmyo, Mayuko Fujita, Tsuyoshi Hiraki, Ko ...
Type: PAPER
Article ID: 2019CTP0002
Published: 2020
[Advance publication] Released: April 09, 2020
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With increasing technology scaling and the use of lower voltages, more research interest is being shown in variability-tolerant analog front end design. In this paper, we describe an adaptive amplitude control transmitter that is operated using differential signaling to reduce the temperature variability effect. It enables low power, low voltage operation by synergy between adaptive amplitude control and Vth temperature variation control. It is suitable for high-speed interface applications, particularly cable interfaces. By installing an aggressor circuit to estimate transmitter jitter and changing its frequency and activation rate, we were able to analyze the effects of the interface block on the input buffer and thence on the entire system. We also report a detailed estimation of the receiver clock-data recovery (CDR) operation for transmitter jitter estimation. These investigations provide suggestions for widening the eye opening of the transmitter.

• Akira TSUCHIYA, Akitaka HIRATSUKA, Kenji TANAKA, Hiroyuki FUKUYAMA, Na ...
Type: PAPER
Article ID: 2019CTP0008
Published: 2020
[Advance publication] Released: April 09, 2020
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This paper presents a design of CMOS transimpedance amplifier (TIA) and peaking inductor for high speed, low power and small area. To realize high density integration of optical I/O, area reduction is an important figure as well as bandwidth, power and so on. To determine design parameters of multi-stage inverter-type TIA (INV-TIA) with peaking inductors, we derive a simplified model of the bandwidth and the energy per bit. Multi-layered on-chip inductors are designed for area-effective inductive peaking. A 5-stage INV-TIA with 3 peaking inductors is fabricated in a 65-nm CMOS. By using multi-layered inductors, 0.02 mm2 area is achieved. Measurement results show 45 Gb/s operation with 49 dBΩ transimpedance gain and 4.4 mW power consumption. The TIA achieves 98 fJ/bit energy efficiency.

• Tsugumichi SHIBATA, Yoshito KATO
Type: PAPER
Article ID: 2019ESP0004
Published: 2020
[Advance publication] Released: April 09, 2020
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Capacitive coupling of line coded and DC-balanced digital signals is often used to eliminate steady bias current flow between the systems or components in various communication systems. A multi-layer ceramic chip capacitor is promising for the capacitor of very broadband signal coupling because of its high frequency characteristics expected from the downsizing of the chip recent years. The lower limit of the coupling bandwidth is determined by the capacitance while the higher limit is affected by the parasitic inductance associated with the chip structure. In this paper, we investigate the coupling characteristics up to millimeter wave frequencies by the measurement and simulations. A phenomenon has been found in which the change in the current distribution in the chip structure occur at high frequencies and the coupling characteristics are improved compared to the prediction based on the conventional equivalent circuit model. A new equivalent circuit model of chip capacitor that can express the effect of the improvement has been proposed.

• Masato TOMIYASU, Keita MORIMOTO, Akito IGUCHI, Yasuhide TSUJI
Type: PAPER
Article ID: 2019ESP0005
Published: 2020
[Advance publication] Released: April 09, 2020
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In this paper, we reformulate a sensitivity analysis method for function-expansion-based topology optimization method without using gray area. In the conventional approach based on function expansion method, permittivity distribution contains gray materials, which are intermediate materials between core and cladding ones, so as to let the permittivity differentiable with respect to design variables. Since this approach using gray area dose not express material boundary exactly, it is not desirable to apply this approach to design problems of strongly guiding waveguide devices, especially for plasmonic waveguides. In this study, we present function-expansion-method-based topology optimization without gray area. In this approach, use of gray area can be avoided by replacing the area integral of the derivative of the matrix with the line integral taking into acount the rate of boundary deviation with respect to design variables. We verify the validity of our approach through applying it to design problems of a T-branching power splitter and a mode order converter.

• Futoshi KUROKI, Shouta SORA, Kousei KUMAHARA
Type: INVITED PAPER
Article ID: 2020MMI0003
Published: 2020
[Advance publication] Released: April 09, 2020
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A ring-resonator type of electrode (RRTE) has been proposed to detect the circulating tumor cell (CTC) for evaluation of the current cancer progression and malignancy in clinical applications. Main emphasis is placed on the identification sensitivity for the lossy materials that can be found in biomedical fields. At first, the possibility of the CTC detection was numerically considered to calculate the resonant frequency of the RRTE catching the CTC, and it was evident that the RRTE with the cell has the resonant frequency inherent in the cell featured by its complex permittivity. To confirm the numerical consideration, the BaTiO3 particle, whose size was similar to that of the CTC, was inserted in the RRTE instead of the CTC as a preliminary experiment. Next, the resonant frequencies of the RRTE with internal organs of the beef cattle such as liver, lung, and kidney were measured for evaluation of the lossy materials such as the CTC, and degraded Q curves were observed because the Q-factors inherent in the internal organs were usually low due to the poor loss tangents. To overcome such difficulty, the RRTE, the oscillator circuit consisting of the FET being added, was proposed to improve the identification sensitivity. Comparing the identification sensitivity of the conventional RRTE, it has been improved because the oscillation frequency spectrum inherent in an internal organ could be easily observed thanks to the oscillation condition with negative resistance. Thus, the validity of the proposed technique has been confirmed.

• Ngoc Quang TA, Hiroshi SHIRAI
Type: PAPER
Article ID: 2019ECP5048
Published: 2020
[Advance publication] Released: April 08, 2020
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Plane wave scattering from a circular conducting cylinder and a circular conducting strip has been formulated by equivalent surface currents which are postulated from the scattering geometrical optics (GO) field. Thus derived radiation far fields are found to be the same as those formulated by a conventional physical optics (PO) approximation for both E and H polarizations.

• Akira KURIYAMA, Hideyuki NAGAISHI, Hiroshi KURODA, Akira KITAYAMA
Type: PAPER
Article ID: 2020MMP0002
Published: 2020
[Advance publication] Released: April 08, 2020
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Smaller antenna structures for long-range radar transmitters and receivers operating in the 77-GHz band for automotive application have been achieved by using antennas with a horn, lens, and microstrip antenna. The transmitter (Tx) antenna height was reduced while keeping the antenna gain high and the antenna substrate small by developing an antenna structure composed of two differential horn and lens antennas in which the diameter and focus distance of the lenses were half those in the previous design. The microstrip antennas are directly connected to the differential outputs of a monolithic microwave integrated circuit. A Tx antenna fabricated using commercially available materials was 14 mm high and had an output-aperture of 18 × 44 mm. It achieved an antenna gain of 23.5 dBi. The antenna substrate must be at least 96 mm2. The antenna had a flat beam with half-power elevation and azimuth beamwidths of 4.5° and 21°, respectively. A receiver (Rx) antenna array composed of four sets of horn and lens antennas with an output-aperture of 9×22 mm and a two-by-two array configuration was fabricated for application in a newly proposed small front-end module with azimuth direction of arrival (DOA) estimation. The Rx antenna array had an antenna coupling of less than -31 dB in the 77-GHz band, which is small enough for DOA estimation by frequency-modulated continuous wave radar receivers even though the four antennas are arranged without any separation between their output-apertures.

• Ryosuke SUGA, Naruki SAITO
Type: PAPER
Article ID: 2019ECP5043
Published: 2020
[Advance publication] Released: March 30, 2020
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A planar electromagnetic field stirrer with periodically arranged metal patterns and diode switches is proposed for improving uneven heating of a heated object placed in a microwave oven. The reflection phase of the proposed stirrer changes by switching the states of diodes mounted on the stirrer and the electromagnetic field in the microwave oven is stirred. The temperature distribution of a heated object located in a microwave oven was simulated and measured using the stirrer in order to evaluate the improving effect of the uneven heating. As the result, the heated parts of the objects were changed with the diode states and the improving effect of the uneven heating was experimentally indicated.