IEICE Transactions on Electronics
Online ISSN : 1745-1353
Print ISSN : 0916-8524
Advance online publication
Displaying 1-50 of 54 articles from this issue
  • Haiyan Sun, Xingyu Wang, Zheng Zhu, Jicong Zhao
    Article type: PAPER
    Article ID: 2022ECP5019
    Published: 2022
    Advance online publication: August 10, 2022
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    In this paper, the spurious modes and quality-factor (Q) values of the one-port dual-mode AlN lamb-wave resonators at 500-1000 MHz were studied by theoretical analysis and experimental verification. Through finite element analysis, we found that optimizing the width of the lateral reflection boundary at both ends of the resonator to reach the quarter wavelength (λ/4), which can improve its spectral purity and shift its resonant frequency. The designed resonators were micro-fabricated by using lithography processes on a 6-inch wafer. The measured results show that the spurious mode can be converted and dissipated, splitting into several longitudinal modes by optimizing the width of the lateral reflection boundary, which are consistent well with the theoretical analysis. Similarly, optimizing the interdigital transducer (IDT) width and number of IDT fingers can also suppress the resonator's spurious modes. In addition, it is found that there is no significant difference in the Qs value for the two modes of the dual-mode resonator with the narrow anchor and full anchor. The acoustic wave leaked from the anchor into the substrate produces a small displacement, and the energy is limited in the resonator. Compared to the resonator with Au IDTs, the resonator with Al IDTs can achieve a higher Q value due to its lower thermo-elastic damping loss. The measured results show the optimized dual-mode lamb-wave resonator can obtain Qs value of 2946.3 and 2881.4 at 730.6 MHz and 859.5 MHz, Qp values of 632.5 and 1407.6, effective electromechanical coupling coefficient (k2eff) of 0.73% and 0.11% respectively, and has excellent spectral purity simultaneously.

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  • Mamoru UGAJIN, Yuya KAKEI, Nobuyuki ITOH
    Article type: PAPER
    Article ID: 2022ECP5009
    Published: 2022
    Advance online publication: August 03, 2022
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    Quadrature voltage-controlled oscillators (VCOs) with current-weight-average and voltage-weight-average phase-adjusting architectures are studied. The phase adjusting equalizes the oscillation frequency to the LC-resonant frequency. The merits of the equalization are explained by using Leeson's phase noise equation and the impulse sensitivity function (ISF). Quadrature VCOs with the phase-adjusting architectures are fabricated using 180-nm TSMC CMOS and show low-phase-noise performances compared to a conventional differential VCO. The ISF analysis and small-signal analysis also show that the drawbacks of the current-weightaverage phase-adjusting and voltage-weight-average phase-adjusting architectures are current-source noise effect and large additional capacitance, respectively. A voltage-average-adjusting circuit with a source follower at its input alleviates the capacitance increase.

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  • Yang Xiao, Zhongyuan Zhou, Changping Tang, Jinjing Ren, Mingjie Sheng, ...
    Article type: PAPER
    Article ID: 2022ECP5001
    Published: 2022
    Advance online publication: July 27, 2022
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    This paper first introduces the structure of a shipboard equipment control cabinet and the preliminary design of electromagnetic shielding, then introduces the principle of low-frequency magnetic field shielding, and uses silicon steel sheet to shield the low-frequency magnetic field of shipboard equipment control equipment. Based on ANSYS Maxwell simulation software, the low-frequency magnetic field radiation emission of the equipment's conducted harmonic peak frequency point is simulated. Finally, according to MIL-STD-461G test standard, the low-frequency magnetic field radiation emission test is carried out, which meets the limit requirements of the standard. The low-frequency magnetic field shielding technology has practical value. The low-frequency magnetic field radiation emission simulation based on ANSYS Maxwell proposed in this paper is a useful attempt for the quantitative simulation of radiation emission.

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  • Naoki Hasegawa
    Article type: INVITED PAPER
    Article ID: 2022MMI0004
    Published: 2022
    Advance online publication: July 19, 2022
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    The expansion of the communication area is expected for Beyond-5G/6G networks using the High Altitude Platform Station (HAPS), Internet of Things (IoT), and sensor devices. Beyond-5G/6G networks constitute the vast amounts of devices that require the latest power utilization system. We expect Microwave Power Transfer (MPT) plays a role in the wireless power supply to HAPS, IoT, and sensors in this network. This work discusses the link design and techniques of MPT for the newest power utilization system required on Beyond-5G/6G networks.

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  • Keigo NAKATANI, Yutaro YAMAGUCHI, Takuma TORII, Masaomi TSURU
    Article type: INVITED PAPER
    Article ID: 2022MMI0006
    Published: 2022
    Advance online publication: July 13, 2022
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    GaN microwave monolithic integrated circuit (MMIC) power amplifiers (PAs) technologies for millimeter-wave (mm-wave) applications are reviewed in this paper. In the mm-wave band, GaN PAs have achieved high-output power as much as traveling wave tube amplifiers used in satellite communications. Additionally, GaN PAs have been integrated enough to be used for 5G and Beyond-5G. In this paper, a high accuracy large-signal GaN-HEMT modeling technique including the trapping effects is introduced in mm-waves. The prototyped PAs designed with the novel modeling technique have achieved RF performance comparable to that of the state-of-the-art GaN PAs in mm-wave.

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  • Long Liu, Gensai Tei, Masahiro Watanabe
    Article type: PAPER
    Article ID: 2022ECP5007
    Published: 2022
    Advance online publication: July 08, 2022
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    We have proposed integrated waveguide structure suitable for mid- and near- infrared light propagation using Si and CaF2 heterostructures on Si substrate. Using a fabrication process based on etching, lithography and crystal growth techniques, we have formed a slab-waveguide structure with a current injection mechanism on a SOI substrate, which would be a key component for Si/CaF2 quantum cascade lasers and other optical integrated systems. The propagation of light at a wavelength of 1.55 μm through a Si/CaF2 waveguide structure have been demonstrated for the first time using a structure with a Si/CaF2 multilayered core with 610-nm-thick, waveguide width of 970 nm, which satisfies single-mode condition in the horizontal direction within a tolerance of fabrication accuracy. The waveguide loss for transverse magnetic (TM) mode has been evaluated to be 51.4 cm-1. The cause of the loss was discussed by estimating the edge roughness scattering and free carrier absorption, which suggests further reduction of the loss would be possible.

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  • Xiangyu MENG, Kangfeng WEI, Zhiyi YU, Xinlun CAI
    Article type: PAPER
    Article ID: 2022ECP5010
    Published: 2022
    Advance online publication: July 01, 2022
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    This paper proposes a low-power 100Gb/s four-level pulse amplitude modulation driver (PAM-4 Driver) based on linear distortion compensation structure for thin-film Lithium Niobate (LiNbO3) modulators, which manages to achieve high linearity in the output. The inductive peaking technology and open drain structure enable the overall circuit to achieve a 31-GHz bandwidth. With an area of 0.292 mm2, the proposed PAM-4 driver chip is designed in a 65-nm process to achieve power consumption of 37.7 mW. Post-layout simulation results show that the power efficiency is 0.37 mW/Gb/s, RLM is more than 96%, and the FOM value is 8.84.

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  • Kotaro AIKAWA, Michihiko SUHARA, Takumi KIMURA, Junki WAKAYAMA, Takesh ...
    Article type: BRIEF PAPER
    Article ID: 2021FUS0006
    Published: 2022
    Advance online publication: June 30, 2022
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    S-parameters of InGaAs/InAlAs triple-barrier resonant tunneling diodes (TBRTDs) were measured up to 67 GHz with various mesa areas and various bias voltages. Admittance data of bare TBRTDs are deembedded and evaluated by getting rid of parasitic components with help of electromagnetic simulations for particular fabricated device structures. Admittance spectroscopy up to 67 GHz is applied for bare TBRTDs for the first time and a Kramers-Kronig relation with Lorentzian function is found to be a consistent model for the admittance especially in cases of low bias conditions. Relaxation time included in the Lorentzian function are tentatively evaluated as the order of several pico second.

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  • K. Saito, K. Yoshida, M. Miura, K. Kanomata, B. Ahmmad, S. Kubota, F. ...
    Article type: PAPER
    Article ID: 2021FUP0001
    Published: 2022
    Advance online publication: June 27, 2022
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    The low temperature deposition of AlN at 160 ℃ is examined by using trimethyl aluminum (TMA) and NH radicals from plasma excited Ar diluted ammonia. For the deposition, a plasma tube separated from the reaction chamber is used to introduce the neutral NH radicals on the growing surface without the direct impacts of high-speed species and UV photons, which might be effective in suppressing the plasma damage to the sample surfaces. To maximize the NH radical generation, the NH3 and Ar mixing ratio is optimized by plasma optical emission spectroscopy. To determine the saturated condition of TMA and NH radical irradiations, an in-situ surface observation of IR absorption spectroscopy (IRAS) with a multiple internal reflection geometry is utilized. The low temperature AlN deposition is performed with the TMA and NH radical exposures whose conditions are determined by the IRAS experiment. The spectroscopic ellipsometry indicates the all-round surface deposition in which the growth per cycles measured from front and backside surfaces of the Si sample are of the same range from 0.39∼0.41 nm/cycle. It is confirmed that the deposited film contains impurities of C, O, N although we discuss the method to decrease them. X-ray diffraction suggests the AlN polycrystal deposition with crystal phases of AlN (100), (002) and (101). From the saturation curves of TMA adsorption and its nitridation, their chemical reactions are discussed in this paper. In the present paper, we discuss the possibility of the low temperature AlN deposition.

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  • K. Saito, K. Yoshida, M. Miura, K. Kanomata, B. Ahmmad, S. Kubota, F. ...
    Article type: PAPER
    Article ID: 2021FUP0002
    Published: 2022
    Advance online publication: June 27, 2022
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    Low-temperature deposition of Y2O3 at 80 ℃ is studied using an yttrium precursor of tris(butylcyclopentadienyl)yttrium (Y(BuCp)3) and plasma exited humidified argon oxidizer. The deposition is demonstrated using an atomic-layer-deposition sequence; the Y(BuCp)3 and the oxidizing gases are time separately introduced to the reaction chamber and these injections are repeated. To determine the gas introduction conditions, surface reactions of Y(BuCp)3 adsorption and its oxidization are observed by an in-situ IR absorption spectroscopy. The deposited film is confirmed as fully oxidized Y2O3 by X-ray photoelectron spectroscopy. The present deposition is applicable for the deposition of Y2O3 film on flexible polyethylene terephthalate films.

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  • Joong-Won Shin, Masakazu Tanuma, Shun-ichiro Ohmi
    Article type: PAPER
    Article ID: 2021FUP0003
    Published: 2022
    Advance online publication: June 27, 2022
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    In this research, we investigated the metal-ferroelectric-semiconductor field-effect transistors (MFSFETs) with 5 nm thick nondoped HfO2 gate insulator by decreasing the sputtering power for Pt gate electrode deposition. The leakage current was effectively reduced to 2.6×10-8 A/cm2 at the voltage of -1.5 V by the sputtering power of 40 W for Pt electrode deposition. Furthermore, the memory window (MW) of 0.53 V and retention time over 10 years were realized.

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  • Masakazu Tanuma, Joong-Won Shin, Shun-ichiro Ohmi
    Article type: PAPER
    Article ID: 2021FUP0004
    Published: 2022
    Advance online publication: June 27, 2022
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    In this research, we investigated the effect of Hf inter layer and chemical oxide on Si(100) substrate on the ferroelectric undoped HfO2 deposition. In case with 1 nm-thick Hf inter layer, equivalent oxide thickness (EOT) was decreased from 6.0 to 4.8 nm for 10 nm-thick HfO2 with decreasing annealing temperature. In case with 0.5 nm-thick chemical oxide, EOT was decreased from 3.9 to 3.6 nm in MFS diodes for 5 nm-thick HfO2. The MFSFET was fabricated with 10 nm-thick HfO2 utilizing Hf inter layer. The subthreshold swing was improved from 240 mV/dec. to 120 mV/dec. and saturation mobility was increased from 70 cm2/(Vs) to 140 cm2/(Vs) by inserting Hf inter layer.

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  • Eun-Ki Hong, Kyung Eun Park, Shun-ichiro Ohmi
    Article type: PAPER
    Article ID: 2021FUP0005
    Published: 2022
    Advance online publication: June 27, 2022
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    In this research, the effect of Ar/N2-plasma sputtering gas pressure on the LaBxNy tunnel and block layer was investigated for pentacene-based floating-gate memory with an amorphous rubrene (α-rubrene) passivation layer. The influence of α-rubrene passivation layer for memory characteristic was examined. The pentacene-based metal/insulator/metal/insulator/semiconductor (MIMIS) diode and organic field-effect transistor (OFET) were fabricated utilizing N-doped LaB6 metal layer and LaBxNy insulator with α-rubrene passivation layer at annealing temperature of 200℃. In the case of MIMIS diode, the leakage current density and the equivalent oxide thickness (EOT) were decreased from 1.2×10-2 A/cm2 to 1.1×10-7 A/cm2 and 3.5 nm to 3.1 nm, respectively, by decreasing the sputtering gas pressure from 0.47 Pa to 0.19 Pa. In the case of floating-gate type OFET with α-rubrene passivation layer, the larger memory window of 0.68 V was obtained with saturation mobility of 2.2×10-2 cm2/(V·s) and subthreshold swing of 199 mV/dec compared to the device without α-rubrene passivation layer.

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  • Xu Bai, Ryusuke Nebashi, Makoto Miyamura, Kazunori Funahashi, Naoki Ba ...
    Article type: BRIEF PAPER
    Article ID: 2021FUS0005
    Published: 2022
    Advance online publication: June 27, 2022
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    A static timing analysis (STA) tool for a 28nm atom-switch FPGA (AS-FPGA) is introduced to validate the signal delay of an application circuit before implementation. High accuracy of the STA tool is confirmed by implementing a practical application circuit on the 28nm AS-FPGA. Moreover, dramatic improvement of delay and power is demonstrated in comparison with a previous 40nm AS-FPGA.

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  • Xiangyu MENG, Yecong LI, Zhiyi YU
    Article type: PAPER
    Article ID: 2022ECP5011
    Published: 2022
    Advance online publication: June 23, 2022
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    This paper proposes a design of high-speed interconnection between optical modules and electrical modules via bonding-wires and coplanar waveguide transmission lines on printed circuit boards for 400 Gbps 4-channel optical communication systems. In order to broaden the interconnection bandwidth, interdigitated capacitors were integrated with GSG pads on chip for the first time. Simulation results indicate the reflection coefficient is below -10 dB from DC to 53 GHz and the insertion loss is below 1 dB from DC to 45 GHz. Both indicators show that the proposed interconnection structure can effectively satisfy the communication bandwidth requirements of 100-Gbps or even higher data-rate PAM4 signals.

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  • Chun-Ping Chen, Zhewang Ma, Tetsuo Anada
    Article type: BRIEF PAPER
    Article ID: 2021ECS6016
    Published: 2022
    Advance online publication: June 15, 2022
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    This brief paper proposes a dual-wideband filter consisting of a parallel-coupled stepped-impedance-resonator (SIR) and open-circuited stubs. Firstly, a notched UWB (ultra-wideband) bandpass filter (BPF) with steep skirt characteristics is theoretically designed. Then a bandstop filter(BSF) is implemented using an SIR and open stubs. By replacing the transmission line part of UWB filter with the BSF, a novel dual-wideband filter (DWBPF) is realized. As a design example, a DWBPF with two passbands, i.e. 3.4-4.8GHz and 7.25-10.25GHz, is designed to validate the design procedure. The designed filter exhibits steep skirt characteristics.

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  • Hiroshi SUZUKI, Tsuyoshi FUNAKI
    Article type: PAPER
    Article ID: 2021ECP5030
    Published: 2022
    Advance online publication: June 14, 2022
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    SiC-MOSFETs are being increasingly implemented in power electronics systems as low-loss, fast switching devices. Despite the advantages of an SiC-MOSFET, its large dv/dt or di/dt has fear of electromagnetic interference (EMI) noise. This paper proposes and demonstrates a simple and robust gate driver that can suppress ringing oscillation and surge voltage induced by the turn-off of the SiC-MOSFET body diode. The proposed gate driver utilizes the channel leakage current methodology (CLC) to enhance the damping effect by elevating the gate-source voltage (VGS) and inducing the channel leakage current in the device. The gate driver can self-adjust the timing of initiating CLC operation, which avoids an increase in switching loss. Additionally, the output voltage of the VGS elevation circuit does not need to be actively controlled in accordance with the operating conditions. Thus, the circuit topology is simple, and ringing oscillation can be easily attenuated with fixed circuit parameters regardless of operating conditions, minimizing the increase in switching loss. The effectiveness and versatility of proposed gate driver were experimentally validated for a wide range of operating conditions by double and single pulse switching tests.

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  • Atsushi Fukuda, Hiroshi Okazaki, Shoichi Narahashi
    Article type: PAPER
    Article ID: 2021ECP5028
    Published: 2022
    Advance online publication: June 10, 2022
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    This paper presents a novel frequency-controlled beam steering scheme for a phased-array antenna system (PAS). The proposed scheme employs phase-controlled carrier signals to form the PAS beam. Two local oscillators (LOs) and delay lines are used to generate the carrier signals. The carrier of one LO is divided into branches, and then the divided carriers passing through the corresponding delay lines have the desired phase relationship, which depends on the oscillation frequency of the LO. To confirm the feasibility of the scheme, four-branch PAS transmitters are configured and tested in a 10-GHz frequency band. The results verify that the formed beam is successfully steered in a wide range, i.e., the 3-dB beamwidth of approximately 100 degrees, using LO frequency control.

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  • Shihao Chen, Takashi Tomura, Jiro Hirokawa, Kota Ito, Mizuki Suga, Yus ...
    Article type: PAPER
    Article ID: 2022ECP5004
    Published: 2022
    Advance online publication: May 23, 2022
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    A waveguide 2-plane hybrid coupler with two operating bands is proposed. The cross-sectional shape of the coupled region inside the proposed coupler is designed with a two-dimensional arbitrary geometry sorting method. Simulations of the proposed hybrid coupler has a fractional bandwidth (FBW) of 2.17% at the center of 24.99GHz, and at the center of 28.28GHz an FBW of 6.13%. The proposed coupler is analyzed by the mode-matching finite-element hybrid method, and the final result is obtained using a genetic algorithm. The analyzed result of the coupling for the main modes in the coupled region is presented. The design result is confirmed by measurements.

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  • Akito IGUCHI, Yasuhide TSUJI
    Article type: INVITED PAPER
    Article ID: 2021ESI0001
    Published: 2022
    Advance online publication: May 20, 2022
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    This paper shows structural optimal design of optical waveguide components utilizing an efficient 3D frequency-domain and 2D time-domain beam propagation method (BPM) with an alternating direction implicit (ADI) scheme. Usual optimal design procedure is based on iteration of numerical simulation, and total computational cost of the optimal design mainly depends on the efficiency of numerical analysis method. Since the system matrices are tridiagonal in the ADI-based BPM, efficient analysis and optimal design are available. Shape and topology optimal design shown in this paper is based on optimization of density distribution and sensitivity analysis to the density parameters. Computational methods of the sensitivity are shown in the case of using the 3D semi-vectorial and 2D time-domain BPM based on ADI scheme. The validity of this design approach is shown by design of optical waveguide components: mode converters, and a polarization beam splitter.

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  • Takuichi Hirano
    Article type: BRIEF PAPER
    Article ID: 2021ESS0002
    Published: 2022
    Advance online publication: May 17, 2022
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    In this paper, the author performed an electromagnetic field simulation of a typical bonding wire structure that connects a chip and a package, and evaluated the signal transmission characteristics (S-parameters). In addition, the inductance per unit length was extracted by comparing with the equivalent circuit of the distributed constant line. It turns out that the distributed constant line model is not sufficient because there are frequencies where chip-package resonance occurs. Below the resonance frequency, the conventional low-frequency approximation model was effective, and it was found that the inductance was about 1 nH/mm.

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  • Liang Fang, Xiao Yan Xu, Tomasz Tarasiuk
    Article type: PAPER
    Article ID: 2021ESP0002
    Published: 2022
    Advance online publication: May 09, 2022
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    Modular multilevel converters (MMCs) are an emerging and promising option for medium voltage direct current (MVDC) of all-electric ships. In order to improve the stability of the MVDC transmission system for ships, this paper presents a new control inputs-based Lyapunov strategy based on feedback linearization. Firstly, a set of dynamics equations is proposed based on separating the dynamics of AC-part currents and MMCs circulating currents. The new control inputs can be obtained by the use of feedback linearization theory applied to the dynamic equations. To complete the dynamic parts of the new control inputs from the viewpoint of MVDC system stability, the Lyapunov theory is designed some compensators to demonstrate the effects of the new control inputs on the MMCs state variable errors and its dynamic. In addition, the carrier phase shifted modulation strategy is used because of applying the few number of converter modules to the MVDC system for ships. Moreover, relying on the proposed control strategy, a simulation model is built in MATLAB/SIMULINK software, where simulation results are utilized to verify the validity of proposed control strategy in the MMC-based MVDC system for ships.

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  • Yan Wang, Qingsheng Hu
    Article type: PAPER
    Article ID: 2021ESP0003
    Published: 2022
    Advance online publication: May 09, 2022
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    This paper presents a channel operating margin (COM) based high-speed serial link optimization using machine learning (ML). COM that is proposed for evaluating serial link is calculated at first and during the calculation several important equalization parameters corresponding to the best configuration are extracted which can be used for the ML modeling of serial link. Then a deep neural network containing hidden layers are investigated to model a whole serial link equalization including transmitter feed forward equalizer (FFE), receiver continuous time linear equalizer (CTLE) and decision feedback equalizer (DFE). By training, validating and testing a lot of samples that meet the COM specification of 400GAUI-8 C2C, an effective ML model is generated and the maximum relative error is only 0.1 compared with computation results. At last 3 link configurations are discussed from the view of tradeoff between the link performance and cost, illustrating that our COM based ML modeling method can be applied to advanced serial link design for NRZ, PAM4 or even other higher level pulse amplitude modulation signal.

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  • Dashan Shi, Heng You, Jia Yuan, Yulian Wang, Shushan Qiao
    Article type: PAPER
    Article ID: 2022ECP5008
    Published: 2022
    Advance online publication: May 06, 2022
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    In this paper, a reference-voltage self-selected pseudo-differential sensing scheme suitable for single-ended SRAM is proposed. The proposed sensing scheme can select different reference voltage according to the offset direction. With the employment of the new sensing scheme, the swing of the read bit-line in the read operation is reduced by 74.6% and 45.5% compared to the conventional domino and the pseudo-differential sense amplifier sensing scheme, respectively. Therefore, the delay and power consumption of the read operation are significantly improved. Simulation results based on a standard 55nm CMOS show that compared with the conventional domino and pseudo-differential sensing schemes, the sensing delay is improved by 66.4% and 47.7%, and the power consumption is improved by 31.4% and 22.5%, respectively. Although the area of the sensing scheme is increased by 50.8% compared with the pseudo-differential sense amplifier sensing scheme, it has little effect on the entire SRAM area.

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  • Katsunori Makihara, Tatsuya Takemoto, Shuji Obayashi, Akio Ohta, Noriy ...
    Article type: PAPER
    Article ID: 2021FUP0006
    Published: 2022
    Advance online publication: April 26, 2022
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    We have fabricated two-tiered heterostructures consisting of phosphorus δ-doped Si quantum dots (Si-QDs) and undoped Si-QDs and studied their electron field emission properties. Electron emission was observed from the P-doped Si-QDs stack formed on the undoped Si-QDs stack by applying a forward bias of ∼6 V, which was lower than that for pure Si-QDs stack. This result is attributed to electric field concentration on the upper P-doped Si-QD layers beneath the layers of the undoped Si-QDs stack due to the introduction of phosphorus atom into the Si-QDs, which was positively charged due to the ionized P donor. The results lead to the development of planar-type electron emission devices with a low-voltage operation.

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  • Jialin Wu, Katsunori Makihara, Hai Zhang, Noriyuki Taoka, Akio Ohta, S ...
    Article type: PAPER
    Article ID: 2021FUP0007
    Published: 2022
    Advance online publication: April 21, 2022
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    We fabricated Fe-silicide nanodots (NDs) on an ultrathin SiO2 layer and evaluated changes in electron transport properties with and without magnetic field application. High-density NDs with an areal density as high as ∼1011 cm-2 were formed on thermally grown SiO2 by exposing ultrathin Fe/Si-NDs structures to a remote H2 plasma without external heating. In electron transport properties related to current-time characteristics for a diode with Fe electrode and charging energy to NDs, clear changes in current levels through NDs and electron injection modulation of NDs depending on intensity of magnetic fields were observed.

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  • Kazuyoshi Ueno
    Article type: PAPER
    Article ID: 2021FUP0008
    Published: 2022
    Advance online publication: April 21, 2022
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    Graphene has been expected as an alternative material for copper interconnects in which resistance increases and reliability deteriorates in nanoscale. While the principle advantages are verified by simulations and experiments, they have not been put into practical use due to the immaturity of the manufacturing process leading to mass production. On the other hand, recent steady progress in the fabrication process has increased the possibility of practical application. In this paper, I will review the recent advances and the latest prospects for conductor applications of graphene centered on interconnects. The possibility of further application utilizing the unique characteristics of graphene is discussed.

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  • Sung Ho Ahn, Gwang Min Sun, Hani Baek, Byung-Gun Park
    Article type: BRIEF PAPER
    Article ID: 2021FUS0001
    Published: 2022
    Advance online publication: April 21, 2022
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    When BJTs are irradiated by gamma rays, interface trapped charges and positive oxide trapped charges are formed by ionization at the Si-SiO2 interface and SiO2 regions, respectively. These trapped charges affect the movement of carriers depending on the type of BJT. This paper presents experimental results regarding operating characteristics of gamma irradiated pnp Si BJTs.

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  • Naoki KAWAMURA, Ryoya SUZUKI, Kotomu NAITO, Yasuhiro HAYAKAWA, Kenji M ...
    Article type: BRIEF PAPER
    Article ID: 2021FUS0002
    Published: 2022
    Advance online publication: April 21, 2022
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    We have investigated the electromotive force (EMF) of a composite sample consisting of a Π-type thermoelectric power generation structure with a pair of n- and p-type Si wafers and piezoelectric devices in order to collect electricity from vibration energy and thermal energy, simultaneously. The observed EMF was obtained by superimposing the oscillating EMF of vibration energy on the constant EMF of thermal energy. Therefore, we have improved the composite sample with diodes for rectifying the oscillating EMF. As a result, the full-wave rectification and the preservation of EMF amplitude were realized. From the frequency dependence, it was found that the dielectric loss of the piezoelectric device influences the amplitude and the time delay in the EMF.

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  • Daiki KANSAKU, Nobuhiro KAWASE, Naoki FUJIWARA, Faizan KHAN, Arockiyas ...
    Article type: BRIEF PAPER
    Article ID: 2021FUS0003
    Published: 2022
    Advance online publication: April 21, 2022
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    To facilitate the reuse of environmental waste heat in our society, we have developed high-efficiency flexible thermoelectric power generators (TEPGs). In this study, we investigated the thermoelectromotive force (TEMF) and output power of a prototype device with 50 pairs of Π-type structures using a homemade measurement system for flexible TEPGs in order to evaluate their characteristics along the thickness direction. The prototype device consisted of C fabrics (CAFs) used as p-type materials, NiCu fabrics (NCFs) used as n-type materials, and Ag fabrics (AGFs) used as metal electrodes. Applying a temperature difference of 5 K, we obtained a TEMF of 150 μV and maximum output power of 6.4 pW. The obtained TEMF was smaller than that expected from the Seebeck coefficients of each fabric, which is considered to be mainly because of the influence of contact thermal resistance at the semiconductor-fabric/AGF interfaces.

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  • Akio WAKEJIMA, Arijit BOSE, Debaleen BISWAS, Shigeomi HISHIKI, Sumito ...
    Article type: INVITED PAPER
    Article ID: 2022MMI0009
    Published: 2022
    Advance online publication: April 21, 2022
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    A detailed investigation of DC and RF performance of AlGaN/GaN HEMT on 3C-SiC/low resistive silicon (LR-Si) substrate by introducing a thick GaN layer is reported in this paper. The hetero-epitaxial growth is achieved by metal organic chemical vapor deposition (MOCVD) on a commercially prepared 6-inch LR-Si substrate via a 3C-SiC intermediate layer. The reported HEMT exhibited very low RF loss and thermally stable amplifier characteristics with the introduction of a thick GaN layer. The temperature-dependent small-signal and large-signal characteristics verified the effectiveness of the thick GaN layer on LR-Si, especially in reduction of RF loss even at high temperatures. In summary, a high potential of the reported device is confirmed for microwave applications.

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  • Nobuyuki Takabayashi, Bo Yang, Naoki Shinohara, Tomohiko Mitani
    Article type: PAPER
    Article ID: 2022MMP0004
    Published: 2022
    Advance online publication: April 21, 2022
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    Drones have been attractive for many kinds of industries, but limited power supply from battery has impeded drones from being operated for longer hours. Microwave power transmission (MPT) is one of the most prospective technologies to release them from the limitation. Since, among several types of drones, micro-drone has shorter available flight time, it is reasonable to provide micro-drone with wireless charging access with a MPT system. However, there is no suitable rectenna for micro-drone charging applications in preceding studies. In this paper, a MPT system for micro-drone was proposed at C-band where a lightweight and compact rectenna array with 20-W class output power was developed. Under illumination of a flat-top beam with 203 mW/cm2 of power density, a 16-element rectenna array was measured. The 16-element rectenna was formed with the aid of a honeycomb substrate for lightness and GaAs Schottky barrier diodes for high output. It was 37.5 g in weight and 146.4 mm by 146.4 mm in size. It output 27.0 W of dc power at 19.0 V at 5.8 GHz when radio frequency power of 280 W was generated by the injection-locked magnetron and 134 W was transmitted from the transmitting phased array. The power-to-weight ratio was 0.72W/g. The power conversion efficiency was 61.9%. These numbers outperformed the rectennas in the preceding studies and suitable for a MPT system to micro-drone.

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  • Kousuke MIYAJI
    Article type: INVITED PAPER
    Article ID: 2021CTI0001
    Published: 2022
    Advance online publication: April 20, 2022
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    There are continuous and strong demands for the DC-DC converter to reduce the size of passive components and increase the system power density. Advances in CMOS processes and GaN FETs enabled the switching frequency of DC-DC converters to be beyond 10MHz. The advancements of 3-D integrated magnetics will further reduce the footprint. In this paper, the overview of beyond-10MHz DC-DC converters will be provided first, and our recent achievements are introduced focusing on 3D-integration of Fe-based metal composite magnetic core inductor, and GaN FET control designs.

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  • Dongyue JIN, Luming CAO, You WANG, Xiaoxue JIA, Yongan PAN, Yuxin ZHOU ...
    Article type: PAPER
    Article ID: 2021ECP5061
    Published: 2022
    Advance online publication: April 18, 2022
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    Fast switching speed, low power consumption, and good stability are some of the important properties of spin transfer torque assisted voltage controlled magnetic anisotropy magnetic tunnel junction (STT-assisted VCMA-MTJ) which makes the non-volatile full adder (NV-FA) based on it attractive for Internet of Things. However, the effects of process variations on the performances of STT-assisted VCMA-MTJ and NV-FA will be more and more obvious with the downscaling of STT-assisted VCMA-MTJ and the improvement of chip integration. In this paper, a more accurate electrical model of STT-assisted VCMA-MTJ is established on the basis of the magnetization dynamics and the process variations in film growth process and etching process. In particular, the write voltage is reduced to 0.7 V as the film thickness is reduced to 0.9 nm. The effects of free layer thickness variation (γtf) and oxide layer thickness variation (γtox) on the state switching as well as the effect of tunnel magnetoresistance ratio variation (β) on the sensing margin (SM) are studied in detail. Considering that the above process variations follow Gaussian distribution, Monte Carlo simulation is used to study the effects of the process variations on the writing and output operations of NV-FA. The result shows that the state of STT-assisted VCMA-MTJ can be switched under -0.3%≤γtf≤6% or -23%≤γtox≤0.2%. SM is reduced by 16.0% with β increases from 0 to 30%. The error rates of writing ‘0' in the NV-FA can be reduced by increasing Vb1 or increasing positive Vb2. The error rates of writing ‘1' can be reduced by increasing Vb1 or decreasing negative Vb2. The reduction of the output error rates can be realized effectively by increasing the driving voltage (Vdd).

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  • Kentaro YOSHIOKA
    Article type: INVITED PAPER
    Article ID: 2021CTI0002
    Published: 2022
    Advance online publication: April 11, 2022
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    LiDAR is a distance sensor that plays a key role in the realization of advanced driver assistance systems (ADAS). In this paper, we present a tutorial and review of automotive direct time of flight (dToF) LiDAR from the aspect of circuit systems. We discuss the breakthrough in ADAS LiDARs through comparison with the first-generation LiDAR systems, which were conventionally high-cost and had an immature performance. We define current high-performance and low-cost LiDARs as next-generation LiDAR systems, which have significantly improved the cost and performance by integrating the photodetector, the readout circuit, and the signal processing unit into a single SoC.

    This paper targets reader who is new to ADAS LiDARs and will cover the basic principles of LiDAR, also comparing with range methods other than dToF. In addition, we discuss the development of this area through the latest research examples such as the 2-chip approach, 2D SPAD array, and 3D integrated LiDARs.

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  • Tetsuya IIZUKA, Meikan CHIN, Toru NAKURA, Kunihiro ASADA
    Article type: PAPER
    Article ID: 2021CTP0001
    Published: 2022
    Advance online publication: April 11, 2022
    JOURNAL FREE ACCESS ADVANCE PUBLICATION

    This paper proposes a reference-clock-less quick-start-up CDR that resumes from a stand-by state only with a 4-bit preamble utilizing a phase generator with an embedded Time-to-Digital Converter (TDC). The phase generator detects 1-UI time interval by using its internal TDC and works as a self-tunable digitally-controlled delay line. Once the phase generator coarsely tunes the recovered clock period, then the residual time difference is finely tuned by a fine Digital-to-Time Converter (DTC). Since the tuning resolution of the fine DTC is matched by design with the time resolution of the TDC that is used as a phase detector, the fine tuning completes instantaneously. After the initial coarse and fine delay tuning, the feedback loop for frequency tracking is activated in order to improve Consecutive Identical Digits (CID) tolerance of the CDR. By applying the frequency tracking architecture, the proposed CDR achieves more than 100 bits of CID tolerance. A prototype implemented in a 65 nm bulk CMOS process operates at a 0.9-2.15 Gbps continuous rate. It consumes 5.1-8.4mA in its active state and 42 μA leakage current in its stand-by state from a 1.0V supply.

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  • Xi FU, Yun WANG, Xiaolin WANG, Xiaofan GU, Xueting LUO, Zheng LI, Jian ...
    Article type: PAPER
    Article ID: 2021CTP0002
    Published: 2022
    Advance online publication: April 11, 2022
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    This paper presents a high-resolution and low-insertion-loss CMOS hybrid phase shifter with a nonuniform matching technique for satellite communication (SATCOM). The proposed hybrid phase shifter includes three 45° coarse phase-shifting stages and one 45° fine phase-tuning stage. The coarse stages are realized by bridged-T switch-type phase shifters (STPS) with 45° phase steps. The fine-tuning stage is based on a reflective-type phase shifter (RTPS) with two identical LC load tanks for phase tuning. A 0.8° phase resolution is realized by this work to support fine beam steering for the SATCOM. To further reduce the chain insertion loss, a nonuniform matching technique is utilized at the coarse stages. For the coarse and fine stages, the measured RMS gain errors at 29 GHz are 0.7 dB and 0.3 dB, respectively. The measured RMS phase errors are 0.8° and 0.4°, respectively. The proposed hybrid phase shifter maintains return losses of all phase states less than -12 dB from 24 GHz to 34 GHz. The presented hybrid phase shifter is fabricated in a standard 65-nm CMOS technology with a 0.14mm2 active area.

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  • Sangyeop LEE, Shuhei AMAKAWA, Takeshi YOSHIDA, Minoru FUJISHIMA
    Article type: BRIEF PAPER
    Article ID: 2021CTS0002
    Published: 2022
    Advance online publication: April 11, 2022
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    A power-scalable wideband distributed amplifier is proposed. For reducing the power consumption of this power-hungry amplifier, it is efficient to lower the supply voltage. However, there is a hurdle owing to the transistor threshold voltage. In this work, a CMOS deeply depleted channel process is employed to overcome the hurdle.

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  • Shinichi TANAKA, Hirotaka ASAMI, Takahiro SUZUKI
    Article type: INVITED PAPER
    Article ID: 2022MMI0002
    Published: 2022
    Advance online publication: April 11, 2022
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    This paper presents a class-E power amplifier (PA) with a novel harmonic tuning circuit (HTC) based on composite right-/left-handed transmission lines (CRLH TLs). One of the issues of conventional harmonically tuned PAs is the limited PAE bandwidth. It is shown by simulation that class-E amplifiers have potential of maintaining high PAE over a wider frequency range than for example class-F amplifiers. To make full use of class-E amplifiers with the superior characteristics, an HTC using double CRLH TL stub structure is proposed. The HTC is not only compact but also enhances the inherently wide operation frequency range of class-E amplifier. A 2-GHz 6W GaN-HEMT class-E PA using the proposed HTC demonstrated a PAE bandwidth (≥ 65%) of 380MHz with maximum drain efficiency and PAE of 78.5% and 74.0 %, respectively.

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  • Takuma Torii, Masaomi Tsuru
    Article type: PAPER
    Article ID: 2022MMP0003
    Published: 2022
    Advance online publication: April 11, 2022
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    In this study, AM-PM compensation of the cross-coupled capacitance neutralization technique is discussed. Cgd neutralization leads to AM-PM compensation of a power amplifier with negligible change of AM-AM characteristics. AM-PM compensation was confirmed via circuit analysis and measurements. The formulation analysis showed that AM-PM compensation can be derived via gm variation against input power with capacitance neutralization. A differential power amplifier with capacitance neutralization was fabricated with GaN high-electron-mobility transistors. The AM-PM characteristic of the fabricated differential power amplifier was measured at 17.7 GHz. It showed AM-PM reduction of 22° at compared to a single-phase power amplifier without capacitance neutralization at output power of 35 dBm.

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  • Marimo MATSUMOTO, Masaya TAMURA
    Article type: PAPER
    Article ID: 2021ECP5058
    Published: 2022
    Advance online publication: March 30, 2022
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    Couplers in a film-type capacitive wireless power charging (CWC) system for an implantable medical device were designed and analyzed in this work. Due to the high conductivity of the human body, two paths contribute to the power transmission, namely a high-frequency current and an electric field. This was confirmed by an equivalent circuit of the system. During analysis of the system, we used pig skin with subcutaneous fat, which has a high affinity with the human body, to search for a highly efficient electrode shape. Subsequently, we fabricated the designed coupler and measured ηmax. An ηmax of 56.6% was obtained for a half-circular coupler with a radius of 20 mm and a distance of 10 mm between adjacent couplers. This study will contribute to the realization of implantable devices that can be recharged during breaks or while sleeping at home, and is expected to significantly reduce the burden on patients.

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  • Hailan Zhou, Longyun Kang, Xinwei Duan, Ming Zhao
    Article type: PAPER
    Article ID: 2021ESP0004
    Published: 2022
    Advance online publication: March 30, 2022
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    In the conventional single-phase PWM rectifier, the sinusoidal fluctuating current and voltage on the grid side will generate power ripple with a doubled grid frequency which leads to a secondary ripple in the DC output voltage, and the switching frequency of the conventional model predictive control strategy is not fixed. In order to solve the above two problems, a control strategy for suppressing the secondary ripple based on the three-vector fixed-frequency model predictive current control is proposed. Taking the capacitive energy storage type single-phase PWM rectifier as the research object, the principle of its active filtering is analyzed and a model predictive control strategy is proposed. Simulation and experimental results show that the proposed strategy can significantly reduce the secondary ripple of the DC output voltage, reduce the harmonic content of the input current, and achieve a constant switching frequency.

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  • Fan Liu, Zhewang Ma, Weihao Zhang, Masataka Ohira, Dongchun Qiao, Guos ...
    Article type: PAPER
    Article ID: 2021ESP0006
    Published: 2022
    Advance online publication: March 30, 2022
    JOURNAL FREE ACCESS ADVANCE PUBLICATION

    A novel compact 5-pole bandpass filter (BPF) using two different types of resonators, one is coaxial TEM-mode resonator and the other dielectric triple-mode resonator, is proposed in this paper. The coaxial resonator is a simple single-mode resonator, while the triple-mode dielectric resonator (DR) includes one TM01δ mode and two degenerate HE11 modes. An excellent spurious performance of the BPF is obtained due to the different resonant behaviors of these two types of resonators used in the BPF. The coupling scheme of the 5-pole BPF includes two cascade triplets (CTs) which produce two transmission zeros (TZs) and a sharp skirt of the passband. Behaviors of the resonances, the inter-resonance couplings, as well as their tuning methods are investigated in detail. A procedure of mapping the coupling matrix of the BPF to its physical dimensions is developed, and an optimization of these physical dimensions is implemented to achieve best performance of the filter. The designed BPF is operated at 1.84 GHz with a bandwidth of 51 MHz. The stopband rejection is better than 20 dB up to 9.7 GHz (about 5.39×f0) except 7.85 GHz. Good agreement between the designed and theoretically synthesized responses of the BPF is reached, verifying well the proposed configuration of the BPF and its design method.

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  • Guowei CHEN, Xujiaming CHEN, Kiichi NIITSU
    Article type: BRIEF PAPER
    Article ID: 2021CTS0001
    Published: 2022
    Advance online publication: March 25, 2022
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    This brief presents a slope analog-digital converter (ADC)-based supply voltage monitor (SVM) for biofuel-cell-powered supply-sensing systems operating in a supply voltage range of 0.18-0.35 V. The proposed SVM is designed to utilize the output of energy harvester extracting power from biological reactions, realizing energy-autonomous sensor interfaces. A burst pulse generator uses a dynamic leakage suppression logic oscillator to generate a stable clock signal under the subthreshold region for pulse counting. A slope-based voltage-to-time converter is employed to generate a pulse width proportional to the supply voltage with high linearity. The test chip of the proposed SVM is implemented in 180-nm CMOS technology with an active area of 0.018 mm2. It consumes 2.1 nW at 0.3 V and achieves a conversion time of 117-673 ms at 0.18-0.35 V with a nonlinearity error of -5.5/+8.3 mV, achieving an energy-efficient biosensing frontend.

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  • Aoi OYANE, Thilak SENANAYAKE, Mitsuru MASUDA, Jun IMAOKA, Masayoshi YA ...
    Article type: PAPER
    Article ID: 2021ECP5048
    Published: 2022
    Advance online publication: March 25, 2022
    JOURNAL FREE ACCESS ADVANCE PUBLICATION

    This paper proposes a topology of high power, MHz-frequency, half-bridge resonant inverter ideal for low-loss Gallium Nitride high electron mobility transistor (GaN-HEMT). General GaN-HEMTs have drawback of low drain-source breakdown voltage. This property has prevented conventional high-frequency series resonant inverters from delivering high power to high resistance loads such as 50Ω, which is typically used in radio frequency (RF) systems. High resistance load causes hard-switching also and reduction of power efficiency. The proposed topology overcomes these difficulties by utilizing a proposed ‘L-S network’. This network is effective combination of a simple impedance converter and a series resonator. The proposed topology provides not only high power for high resistance load but also arbitrary design of output wattage depending on impedance conversion design. In addition, the current through the series resonator is low in the L-S network. Hence, this series resonator can be designed specifically for harmonic suppression with relatively high quality-factor and zero reactance. Low-distortion sinusoidal 3kW output is verified in the proposed inverter at 13.56MHz by computer simulations. Further, 99.4% high efficiency is achieved in the power circuit in 471W experimental prototype.

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  • Hiroshi YAMAMOTO, Ken KIKUCHI, Valeria VADALÀ, Gianni BOSI, Antonio RA ...
    Article type: INVITED PAPER
    Article ID: 2022MMI0003
    Published: 2022
    Advance online publication: March 25, 2022
    JOURNAL FREE ACCESS ADVANCE PUBLICATION

    This paper describes the efficiency-limiting factors resulting from transistor current source in the case of class-F and inverse class-F (F-1) operations under saturated region. We investigated the influence of knee voltage and gate-voltage clipping behaviors on drain efficiency as limiting factors for the current source. Numerical analysis using a simplified transistor model was carried out. As a result, we have demonstrated that the limiting factor for class-F-1 operation is the gate-diode conduction rather than knee voltage. On the other hand, class-F PA is restricted by the knee voltage effects. Furthermore, nonlinear measurements carried out on a GaN HEMT validate our analytical results.

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  • Kenji Itoh, Naoki Sakai, Keisuke Noguchi
    Article type: INVITED PAPER
    Article ID: 2022MMI0007
    Published: 2022
    Advance online publication: March 25, 2022
    JOURNAL FREE ACCESS ADVANCE PUBLICATION

    In this paper, a high-efficiency high-power rectenna with a bridge diode and the diode on antenna (DoA) topology is discussed. First, the topologies of rectifiers and rectennas are discussed to indicate the direction for obtaining highly efficient rectification. Rectifiers with well-matched diode pairs, as double voltage and bridge rectifiers, can reactively terminate even order harmonics, and is suitable for highly efficient operation. A rectenna with the DoA topology is suitable for a direct connection between the highly functional antenna and the rectifier diodes to remove lossy circuit portions. Next, the formulas for the rectification efficiency of the bridge rectifier are demonstrated with the behavioral model. The indicated formulas clarify the fundamental limitation on the rectification efficiency, which is the design goal in case of the DoA topology. Finally, we demonstrate a 5.8 GHz band 1 W rectenna with the bridge diode and the DoA topology. The bridge rectifier that is directly connected to the inductive high-impedance antenna achieved a rectification efficiency of 92.8% at an input power of 1 W. This is close to the fundamental limitation due to the diode performance.

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  • Yasunori Suzuki, Tetsuo Hirota, Toshio Nojima
    Article type: PAPER
    Article ID: 2022MMP0005
    Published: 2022
    Advance online publication: March 25, 2022
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    This paper proposes a new multi-port amplifier configuration that employs feed-forward techniques. In general, a multi-port amplifier is used as a transponder in a satellite transmitter. A multi-port amplifier comprises an N-in N-out input-side matrix network, N amplifiers, and an N-in N-out output-side matrix network. Based on this configuration, other undesired ports leak power to the desired port in a multi-port amplifier. If the power amplifier of a cellular base station uses a multi-port amplifier, the power leakage from the other ports causes degradation in the error vector magnitude. The proposed configuration employs N-parallel feed-forward amplifiers with a multi-port amplifier as the main amplifier. The proposed configuration drastically reduces the power leakage using the employed feed-forward techniques. An experimental 2-GHz band four-in four-out multi-port amplifier is constructed and tested. It achieves the leakage power level of -58 dB, a gain deviation of less than 0.05 dB, and a phase deviation of less than 0.45 deg. with the maximum power of 35 dBm over a 20-MHz bandwidth with the center frequency 2.14 GHz at room temperature. The experimental multi-port amplifier reduces the leakage power level by approximately 30 dB compared to that for a multi-port amplifier without the feed-forward techniques. The proposed configuration can be applied to power amplifiers in cellular base stations.

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  • Naoya HIEDA, Keita MORIMOTO, Akito IGUCHI, Yasuhide TSUJI, Tatsuya KAS ...
    Article type: PAPER
    Article ID: 2021ESP0005
    Published: 2022
    Advance online publication: March 24, 2022
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    In order to increase communication capacity, the use of millimeter-wave and terahertz-wave bands are being actively explored. Non-radiative dielectric waveguide known as NRD guide is one of promising platform of millimeter-wave integrated circuits thanks to its non-radiative and low loss nature. In order to develop millimeter wave circuits with various functions, various circuit components have to be efficiently designed to meet requirements from application side. In this paper, for efficient design of NRD guide devices, we develop a topology optimal design technique based on function-expansion-method which can express arbitrary structure with arbitrary geometric topology. In the present approach, recently developed two-dimensional full-vectorial finite element method (2D-FVFEM) for NRD guide devices is employed to improve computational efficiency and several evolutionary approaches, which do not require appropriate initial structure depending on a given design problem, are used to optimize design variables, thus, NRD guide devices having desired functions are efficiently obtained without requiring designer's special knowledge.
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  • Kazuhiro FUJITA
    Article type: BRIEF PAPER
    Article ID: 2021ESS0001
    Published: 2022
    Advance online publication: March 24, 2022
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    The hybrid implicit-explicit single-field finite-difference time-domain (HIE-SF-FDTD) method based on the wave equation of electric field is reformulated in a concise matrix-vector form. The global approximation error of the scheme is discussed theoretically. The second-order convergence of the HIE-SF-FDTD is numerically verified.

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