Hang Liu Fei Wu
Keiji GOTO Toru KAWANO Ryohei NAKAMURA
Takahiro SASAKI Yukihiro KAMIYA
Xiang XIONG Wen LI Xiaohua TAN Yusheng HU
Anton WIDARTA
Hiroshi OKADA Mao FUKINAKA Yoshiki AKIRA
Shun-ichiro Ohmi
Tohgo HOSODA Kazuyuki SAITO
Shohei Matsuhara Kazuyuki Saito Tomoyuki Tajima Aditya Rakhmadi Yoshiki Watanabe Nobuyoshi Takeshita
Koji Abe Mikiya Kuzutani Satoki Furuya Jose A. Piedra-Lorenzana Takeshi Hizawa Yasuhiko Ishikawa
Yihan ZHU Takashi OHSAWA
Shengbao YU Fanze MENG Yihan SHEN Yuzhu HAO Haigen ZHOU
Ryo KUMAGAI Ryosuke SUGA Tomoki UWANO
Jun SONODA Kazusa NAKAMICHI
Kaiji Owaki Yusuke Kanda Hideaki Kimura
Takuya FUJIMOTO
Yuji Wada
Fuyuki Kihara Chihiro Matsui Ken Takeuchi
Keito YUASA Michihiro IDE Sena KATO Kenichi OKADA Atsushi SHIRANE
Tomoo Ushio Yuuki Wada Syo Yoshida
Futoshi KUROKI
Jun FURUTA Shotaro SUGITANI Ryuichi NAKAJIMA Takafumi ITO Kazutoshi KOBAYASHI
Yuya Ichikawa Ayumu Yamada Naoko Misawa Chihiro Matsui Ken Takeuchi
Ayumu Yamada Zhiyuan Huang Naoko Misawa Chihiro Matsui Ken Takeuchi
Yoshinori ITOTAGAWA Koma ATSUMI Hikaru SEBE Daisuke KANEMOTO Tetsuya HIROSE
Hikaru SEBE Daisuke KANEMOTO Tetsuya HIROSE
Zhibo CAO Pengfei HAN Hongming LYU
Takuya SAKAMOTO Itsuki IWATA Toshiki MINAMI Takuya MATSUMOTO
Koji YAMANAKA Kazuhiro IYOMASA Takumi SUGITANI Eigo KUWATA Shintaro SHINJO
Minoru MIZUTANI Takashi OHIRA
Katsumi KAWAI Naoki SHINOHARA Tomohiko MITANI
Baku TAKAHARA Tomohiko MITANI Naoki SHINOHARA
Akihiko ISHIWATA Yasumasa NAKA Masaya TAMURA
Atsushi Fukuda Hiroto Yamamoto Junya Matsudaira Sumire Aoki Yasunori Suzuki
Ting DING Jiandong ZHU Jing YANG Xingmeng JIANG Chengcheng LIU
Fan Liu Zhewang Ma Masataka Ohira Dongchun Qiao Guosheng Pu Masaru Ichikawa
Ludovico MINATI
Minoru Fujishima
Hyunuk AHN Akito IGUCHI Keita MORIMOTO Yasuhide TSUJI
Kensei ITAYA Ryosuke OZAKI Tsuneki YAMASAKI
Akira KAWAHARA Jun SHIBAYAMA Kazuhiro FUJITA Junji YAMAUCHI Hisamatsu NAKANO
Seiya Kishimoto Ryoya Ogino Kenta Arase Shinichiro Ohnuki
Yasuo OHTERA
Tomohiro Kumaki Akihiko Hirata Tubasa Saijo Yuma Kawamoto Tadao Nagatsuma Osamu Kagaya
Haonan CHEN Akito IGUCHI Yasuhide TSUJI
Keiji GOTO Toru KAWANO Munetoshi IWAKIRI Tsubasa KAWAKAMI Kazuki NAKAZAWA
Tetsuya SUEMITSU Tetsuyoshi ISHII Yasunobu ISHII
InP-based high electron mobility transistors (HEMTs) with gate lengths reduced to 30 nm were fabricated and characterized, and the effect of the gate recess on the high-frequency characteristics was studied. The cutoff frequency, which is regarded as a function of the gate length and the average carrier velocity in a first-order approximation, depends on the size of the gate recess when the gate length becomes short. The size of the gate recess is optimized by taking the feed-back capacitance and the parasitic resistance into account. For HEMTs having the gate recess with an InP surface, an appropriate widening of the gate recess gives a record cutoff frequency of 368 GHz for the 30-nm-gate HEMTs with a lattice-matched channel.
Jesus A. del ALAMO Roxann R. BLANCHARD Samuel D. MERTENS
We have carried out a systematic study of the impact of hydrogen exposure on InP HEMTs and GaAs PHEMTs with Ti/Pt/Au gates. Hydrogen poisoning is an important reliability concern in these devices. Our work has provided ample evidence supporting the formation of TiH inside the gate structure upon exposure of HEMTs to a hydrogen environment. The resulting volume expansion of the gate stresses the semiconductor heterostructure underneath and, through the piezoelectric effect, results in a shift of the threshold voltage of the device. This mechanism is largely reversible. Independently of this, we have found that H2 upsets the stoichiometry of the exposed InAlAs barrier in the recessed region right next to the gate. This irreversebly changes the extrinsic sheet carrier concentration in the channel and affects other figures of merit such as the breakdown voltage. This understanding should be instrumental in identifying device-level solutions to this problem.
Naoki HARA Yasuhiro NAKASHA Toshihide KIKKAWA Kazukiyo JOSHIN Yuu WATANABE Hitoshi TANAKA Masahiko TAKIKAWA
We have developed InGaP-channel field effect transistors (FETs) with high breakdown voltages that can be fabricated by using conventional GaAs FET fabrication processes. The buffer and barrier layers were also optimized for the realization of high-voltage operation. The InGaP-channel FET has an extremely high on-state drain-to-source breakdown voltage of over 40 V, and a gate-to-drain breakdown voltage of 55 V. This enabled high-voltage large-signal operation at 40 V. The third-order intermodulation distortion of the InGaP channel FETs was 10-20 dB lower than that of an equivalent GaAs-channel FET, due to the high operating voltage.
Shigeru NAKAJIMA Ken NAKATA Kunio TANAKA Kenji OTOBE
An InGaP/GaAs composite channel has been proposed in order to improve the electron transport properties of InGaP for high power device applications. The electron mobility and velocity are increased due to the contribution of high mobility GaAs. Although the composite channel FET shows higher transconductance and drain current than those of the InGaP single channel FET, the breakdown voltage is nearly the same. The composite channel FET delivered output power of 0.6 W/mm with power added efficiency of 46.2% under 17 V operation at 1.9 GHz.
Feng-Tso CHIEN Hsien-Chin CHIU Shih-Cheng YANG Chii-Wen CHEN Yi-Jen CHAN
Devices DC, RF, and microwave power performances between Al0.3Ga0.7As/In0.15Ga0.85As double doped-channel FET (D-DCFETs), conventional doped-channel FETs (DCFETs) and HEMTs are compared with each other. Device linearity and power performance have been improved by a double doped-channel design. The D-DCFETs provides a higher current density, higher gate breakdown voltage, and improves gate operation bias range as well as frequency performance. The linear power gain and output power for D-DCFETs is 19 dB and 305 mW/mm with a power-added efficiency of 52% at Vds = 2.5 V under a 1.9 GHz operation. These advantages suggest that double doped-channel design is more suitable for a high linearity and high microwave power device applications.
Hsien-Chin CHIU Shih-Cheng YANG Yi-Jen CHAN Hao-Hsiung LIN
A high barrier Schottky gate on InGaP/InGaAs doped-channel FETs (DCFETs) provides a high current density, high gate-to-drain breakdown voltage and a better linear operation over a wide gate bias range. However, these doped-channel devices are limited by a large parasitic resistance associated with a 20 nm thick undoped InGaP layer beneath the gate metal. In this study, we inserted a Si δ-doped layer inside this high bandgap undoped InGaP layer to reduce parasitic resistances and to enhance device DC and RF power performance. These modified DCFETs (M-DCFETs) demonstrated an output power density of 204 mW/mm, a power-added efficiency of 45%, and a linear power gain of 18.3 dB for an 1 mm gate-width device under a 2.4 GHz operation. These characteristics suggest that doped-channel FETs with a Si δ-doped layer provide a good potential for high power microwave device applications.
Takashi MIZUTANI Makoto YAMAMOTO Shigeru KISHIMOTO Koichi MAEZAWA
The low-frequency noise of InGaAs pseudomorphic HEMTs fabricated on GaAs substrate was studied. The dependence of the noise spectral density on the gate voltage indicates that the channel of the device dominates the low-frequency noise. Generation-recombination (G-R) noise was observed in the form of bulges superimposed on a background of 1/f. The activation energyof the G-R noise was 0.32-0.39 eV which is close to that of the DX center, suggesting that the origin of the G-R noise is the DX center in the AlGaAs barrier layer. Little bulge was observed in the gate current noise of the HEMTs with large InAs mole fractions of 0.4 and 0.5. Generation of the traps with different time constant can explain this behavior.
Yoshiharu ANDA Katsuhiko KAWASHIMA Mitsuru NISHITSUJI Tsuyoshi TANAKA
We report 0.15-µm T-shaped gate MODFETs using BCB (Benzocyclobutene) as low-k spacer dielectric material. The RF performance of pseudomorphic MODFET was improved by reducing the gate fringing capacitance using low-k material. The BCB film was deposited by plasma CVD technique at 100
Akira ENDOH Yoshimi YAMASHITA Masataka HIGASHIWAKI Kohki HIKOSAKA Takashi MIMURA Satoshi HIYAMIZU Toshiaki MATSUI
We fabricated 50-nm-gate InAlAs/InGaAs high electron mobility transistors (HEMTs) lattice-matched to InP substrates by using a conventional process under low temperatures, below 300
Yong-Gui XIE Seiya KASAI Hiroshi TAKAHASHI Chao JIANG Hideki HASEGAWA
A novel InGaAs/InAlAs insulated gate (IG) pseudomorphic high electron mobility transistor (PHEMT) having a silicon interface control layer (Si ICL) is successfully fabricated and characterized. Systematic efforts to characterize and optimize the insulated gate structure and the PHEMT fabrication process were made by using in-situ X-ray photoelectron spectroscopy (XPS) and capacitance-voltage (C-V) techniques. This led to successful fabrication of a novel IG-PHEMT showing excellent stable DC characteristics with a good pinch off and a high transconductance (177 mS/mm), very small gate leakage currents, very high gate breakdown voltages (about 40 V) and respectable RF characteristics fT = 9 GHz and fmax=38 GHz.
Hiroshi TAKAHASHI Masatsugu YAMADA Yong-Gui XIE Seiya KASAI Hideki HASEGAWA
The fabrication process of a novel Si interface control layer (Si ICL)-based oxide-free insulated gate structure for InP metal-insulator-semiconductor field effect transistors (MISFETs) was successfully characterized and optimized using in-situ reflection of high-energy electron diffraction (RHEED), Raman scattering spectroscopy, X-ray photoelectron spectroscopy (XPS) and capacitance-voltage (C-V) techniques, and applied for fabrication of MISFETs. RHEED observation indicated that the optimum initial thickness of the Si ICL with single crystal pseudomorphic growth of Si on InP is 10
Shinichi HOSHI Takayuki IZUMI Tomoyuki OHSHIMA Masanori TSUNOTANI Tamotsu KIMURA
The reduction of the drain current for InGaAs/AlGaAs pseudomorphic high electron mobility transistors (PHEMTs) has been observed due to the RIE-damage induced under the gate region. However, it has been found that the drain current can be recovered after the gate-drain reverse current stress even at room temperature. The recovery rate of the drain current strongly depends on the gate-drain reverse current density. The activation energy of the recovery rate has been confirmed to decrease from 0.531 eV to 0.119 eV under the gate-drain reverse current stress. This phenomenon can be understood as a recombination enhanced defect reaction of holes generated by the avalanche breakdown. The non-radiative recombination of holes at the defect level is believed to enhance the recovery of the RIE-damage.
Yasuyuki MIYAKE Koichi HOSHINO
In this report we demonstrate the characteristics of the opt-electrical transducer that is newly designed for a fiber-optic wireless access system. This transducer consists of a monolithic microwave integrated circuit (MMIC) oscillator whose oscillation frequency is over 30 GHz. The active element of the oscillator is an InAlAs/InGaAs high electron mobility transistor (HEMT). The shift of frequency is observed when we illuminate 1.55 µm wavelength light onto the HEMT area. The size of the frequency shift is -150 MHz/mW, and it does not change as a function of gate bias conditions. We also confirm that the oscillator is able to respond with an optical signal of 500 MHz, which is sufficiently fast to achieve 156 Mbit/s communication. If this transducer is introduced into the base station (BS) of a fiber-optic wireless access system, a high-speed optical modulator no longer has to be incorporated into the control station. As a result, the configuration of the system becomes simpler than that of Radio on Fiber. We constructed a system that adopts the frequency shift keying technique with application of the transducer into the BS and then performed a transmission experiment at 5 Mbit/s. The demodulated data is sufficiently clear to distinguish high from low. Therefore, we can put forth that the fabricated transducer is a promising candidate as a device for the BS of a fiber-optic millimeter-wave wireless access system.
By using the gain expansive and compressive characteristics of two FET to compensate for the phase shift at large signal, one can greatly improve Adjacent Channel Power Ratio (ACPR) of the power amplifier. This 3 to 5 dB improvement result was verified experimentally by selecting the biasing point and the gain level of the first and second stage amplifiers. This MCM circuit-level technique is more attractive to achieve low cost and good ACPR design. As examples, some novel high efficiency power amplifiers with good ACPR for the handset applications are developed by this method. Those mass producible 0.12 cc volume (7.8
Noren PAN Roger E. WELSER Kevin S. STEVENS Charles R. LUTZ
The long-term reliability of heterojunction bipolar transistor (HBT) continues to be a subject of great interest due to the increased acceptance of this device in a wide range of applications. The most demanding requirements for long-term reliability include high performance microwave instrumentation, X-band radar, and lightwave communication (OC-192). A significant leap in the long-term reliability performance was observed in HBT as the AlGaAs emitter material was replaced with lattice matched InGaP. A dramatic improvement in the long-term reliability was also observed in AlGaAs emitter HBT's as the turn on voltage (Vbe) was lowered. The typical failure mechanism in HBT devices at high current density and high temperature long-term reliability testing was a dramatic increase in the base current at low current densities. One of the limiting factors in obtaining MTTF in InGaP HBT was the long time required to promote failures in the HBT device. Furthermore, a large sample size is necessary to extract a reliable MTTF. Significant increases in the current density as high as 180 kA/cm2 during reliability testing was used to promote failures in order to obtain an MTTF within a reasonable amount of time. The MTTF at a junction temperature of 334
William Ross McKINNON Rachid DRIAD Craig STOREY Anthony RENAUD Sean P. McALISTER Ted GARANZOTIS Anthony J. SPRINGTHORPE
The current-voltage characteristics of InP-based HBTs with InAlAs-InP composite emitters have been measured as a function of the thickness of the InP layer in the emitter. As the thickness varies, characteristics such as the gain and the ideality factor vary qualitatively as expected from the changes in position of the InAlAs barrier in the emitter. Quantitatively, however, the variations indicate that the interfaces vary systematically with InP thickness, becoming more abrupt for emitters with thicker InP layers.
Keiichi MURAYAMA Masaaki NISHIJIMA Manabu YANAGIHARA Tsuyoshi TANAKA
The temperature compensation technique of InGaP/GaAs power heterojunction bipolar transistor (HBT) with novel bias circuit using Schottky diodes has been developed. The variation in the quiescent current to the temperature is less than 30% from -30
Fritz SCHUERMEYER Peter J. ZAMPARDI Sharon FITZSIMMONS Roger E. WELSER Noren PAN
Photoelectric techniques, such as photoluminescence are commonly used to evaluate and qualify heterostructure materials. These studies provide invaluable information on the energy configuration of these devices. In this paper, we extend photoelectric techniques to the evaluation of fully fabricated HBTs. We describe photoconduction measurements performed on the base/collector junctions in GaAs based HBTs. The devices studied contained a window in the emitter metal and monochromatic, chopped light was focused through a microscope into the window. The measurements are performed on wafer at room temperature. The spectral characteristic of the photocurrent provides information on the material and allows the determination of the source of the measured photocurrent. The dependence of the photocurrent on the junction bias allows the profiling of the junction. Three different collector structures were investigated, containing GaAs, AlGaAs, and InGaP. The effects of electron and hole barriers are evaluated. The information obtained allows for the design of improved HBTs.
Roger E. WELSER Paul M. DELUCA Alexander C. WANG Noren PAN
We report here on the electrical and structural characteristics of InGaP/GaInAsN DHBTs with up to a 50 mV reduction in turn-on voltage relative to standard InGaP/GaAs HBTs. High p-type doping levels (
Toshiki ARAI Shigeharu YAMAGAMI Yoshifumi OKUDA Yoshimichi HARADA Yasuyuki MIYAMOTO Kazuhito FURUYA
Fabrication process for narrow emitter along
Konrad WOLF Wolfgang KLEIN Norbert ELBEL Adrian BERTHOLD Sonja GRONDAHL Thomas HUTTNER Stefan DREXL Rudolf LACHNER
We report the process flow and technological features of Infineons' 75 GHz bipolar technology, which is characterized by a double-poly self-aligned transistor structure and a SiGe base, grown by selective epitaxy. The dependence of the epitaxial deposition on growth conditions and the influence of layout on the growth process is discussed, especially for different kinds of reticles: bipolar-ICs, BICMOS-ICs and discrete semiconductors. Finally, our monitoring concept for the control of the selective SiGe epitaxy is presented and compared with alternative methods of process control.
Pei-Der TSENG Liyang ZHANG Mau-Chung Frank CHANG
This paper compares the performance of SiGe and GaAs HBT power amplifiers for wireless handset applications. To make a fair comparison, we have designed and characterized monolithic SiGe power amplifiers and compared their performance with similarly designed commercial GaAs power amplifiers for both cellular dual-mode (CDMA/AMPS) and PCS CDMA handsets. The designed SiGe cellular power amplifier, at 824-849 MHz, satisfies both CDMA and AMPS requirements in output power, linearity and efficiency. At Vcc = 3 V, the power amplifier shows excellent linearity (1st ACPR < -44.1 dBc and 2nd ACPR < -57.1 dBc) up to 28 dBm for CDMA applications. Under the same bias conditions, the power amplifier also meets AMPS handset requirements in output power (up to 31 dBm) and linearity (with 2nd and 3rd harmonic to fundamental ratios lower than -37 dBc and -55 dBc, respectively). At the maximum output power level, the worst power-added-efficiencies (PAE) are measured to be 36% for CDMA and 49% for AMPS operations. The performance of SiGe cellular power amplifiers is comparable to that of GaAs HBT power amplifiers but with two exceptions: 1) SiGe power amplifier showed a relatively low gain than that of GaAs amplifiers (about 4-6 dB). This may be attributed to the use of low-Q inductors (Q < 5) for on-chip impedance matching, imprecise device modeling and the higher interconnect parasitics; 2) SiGe power amplifiers survived severe output mismatch (VSWR > 12:1) up to Vcc = 4 V but died instantly as Vcc > 4.5 V, due to their low breakdown voltages. We also observed inter-modulation spurs (-22 dBc) appeared in CDMA outputs at two specific tuning angles, but with no spurs appeared in AMPS outputs at any tuning angle. The possible mechanism for generating those output spurs will be discussed as well. In addition, We also designed and characterized a monolithic SiGe power amplifier for PCS (1850-1910 MHz) CDMA handset applications. At Vcc = 3.5 V, the SiGe PA satisfies the linearity requirement up to maximum power output 28 dBm with a comparable gain (23-26 dBm), but has a relatively low PAE (
Christos PAPAVASSILIOU Kristel FOBELETS Chris TOUMAZOU
Silicon Germanium Heterostructure field effect transistors have been proposed as a promising extension to the CMOS technologies affording enhanced performance at relaxed geometries. Particularly promising is the potential of SiGe Heterostructure MOS and Heterostrucure FET at the low power operating regime. We discuss circuit design techniques applicable in the micropower regime which can be applied to SiGe HMOS technologies. We then review recent results in HMOS both from the material and the applications point of view. We conclude by reporting simulation results indicating the potential of SiGe HMOS in radiofrequency micropower applications.
Tomohisa MIZUNO Naoharu SUGIYAMA Atsushi KUROBE Shin-ichi TAKAGI
We have developed advanced SOI n- and p-MOSFETs with strained-Si channel on insulator (strained-SOI) structure fabricated by SIMOX (separation-by-implanted-oxygen) technology. The characteristics of this strained-SOI substrate and electrical properties of strained-SOI MOSFET's have been experimentally studied. Using strained-Si/relaxed-SiGe epitaxy technology and usual SIMOX process, we have successfully formed the layered structure of fully-strained-Si (20 nm)/fully-relaxed-SiGe film (290 nm) on uniform buried oxide layer (85 nm) inside SiGe layer. Good drain current characteristics have been obtained in strained-SOI MOSFET's. It is found that both electron and hole mobility is enhanced in strained-SOI MOSFET's, compared to the universal mobility in an inversion layer and the mobility of control SOI MOSFET's. These mobility enhancement factors are almost the same as the theoretical results.
Sean P. McALISTER Craig STOREY Stephen J. KOVACIC Hugues LAFONTAINE
The low bias region of the base current has been studied in SiGe HBTs and shown to arise from tunneling at the emitter periphery. Tunneling also describes the reverse bias base-emitter current, which we believe is enhanced by mid-gap states. The reverse bias causes damage to the base-emitter region, increasing the base current. We also show that after a short period of severe reverse bias stress the base current displays random telegraph signals. These phenomena are often observed in silicon bipolar transistors, confirming that the incorporation of SiGe has not produced any other undesirable characteristics.
Gunter GRAU Ulrich LANGMANN Wolfgang WINKLER Dieter KNOLL Klaus PRESSEL
We present a 5.8 GHz VCO for the 5 GHz HIPERLAN/2 and U-NII band. The VCO uses a center-tapped inductor and a substrate shield to improve phase noise. Sensitivity to supply voltage and temperature is reduced by an amplitude control block. The design is based on a distributed inductor model which allows optimization without antecedent inductor measurements. The circuit is fabricated in a 0.8 µ m 45 GHz fT low-cost SiGe-HBT technology and operates with a supply voltage of -2.0 V to -3.3 V .
Helmut LEIER Andrei VESCAN Ron DIETRICH Andreas WIESZT Hardy Hans SLEDZIK
In this paper we summarize the actual status of the GaN/AlGaN HFET power technology at DaimlerChrysler using high quality structures grown by MOCVD on sapphire or semi-insulating SiC supplied by Epitronics. High mobilites and record extrinsic transconductance and current values were achieved on devices with sapphire and SiC substrate. Small area devices with 0.3 µm gate length yield fT=43 GHz and fmax=78 GHz (s.i. SiC substrate). Load-pull characterisation have been performed on multifinger HFETs up to 20 GHz with e.g. output power levels above 3 Watt cw at 15 GHz for a single 1.6 mm device. Though the achieved results are very promising, the performance of these devices is still hampered by transient effects on different time scales. We will show in this paper that passivation of the devices by SiN could considerably improve the RF power performance as well as reduce long time constant effects present before passivation.
Hiroshi ITO Tomofumi FURUTA Tadao ISHIBASHI
This paper describes the recent progress in the device performance of the uni-traveling-carrier photodiode (UTC-PD). The UTC-PD utilizes only electrons as the active carriers and this unique feature is the key to achieving excellent high-speed and high-output characteristics simultaneously. The achieved performance includes a record 3-dB bandwidth (f3dB) of 310 GHz, a high output current over 180 mA with an f3dB of 65 GHz, a high linearity of up to 80 mA, and a zero-bias operation with an f3dB of 230 GHz and an output peak current of 6.8 mA.
Tamotsu HASHIZUME Ryuusuke NAKASAKI Shin-ya OOTOMO Susumu OYAMA Hideki HASEGAWA
Surface passivation process of GaN utilizing electron-cyclotron-resonance (ECR) excited plasma has been characterized and optimized for realization of stable operation in GaN-based high-power/high-frequancy electronic devices. From XPS analysis, the NH4OH treatment as well as the ECR-N2 and ECR-H2 plasma treatments were found to be effective in removing natural oxide and contaminants from the GaN surface. The SiNx/GaN structure prepared by the ECR excited plasma chemical vapor deposition (ECR-CVD) process showed better C-V behavior compared to the SiO2/GaN structure. Surface treatment process using the ECR plasma improved interface properties and achieved the Dit value of 2
Egor ALEKSEEV Dimitris PAVLIDIS William Earl SUTTON Edwin PINER Joan REDWING
Theoretical and experimental aspects of GaN-based Gunn diodes are reviewed. Since the threshold field for Gunn effect in GaN (FTH>150 kV/cm) is reported to be much higher than in GaAs (FTH=3.5 kV/cm), the active layer of GaN-based devices can be made thinner (<3 µm) and doped higher (>1017 cm-3) than in conventional Gunn diodes. Consequently, GaN-based devices are expected to offer increased frequency and power capabilities. The advantages of GaN are demonstrated with the help of large-signal simulations of GaN and GaAs Gunn diodes. The simulations revealed that GaN diodes can be operated at a higher frequency (up to 760 GHz vs. 100 GHz) and with larger output power density (105 W/cm2 vs. 103 W/cm2) than GaAs diodes. Epitaxial layers of n+/n-/n+ GaN (1019 cm-3/1017 cm-3/1019 cm-3) designed for millimeter-wave operation were grown using MOCVD on SiC substrates. GaN Gunn diodes with 4 µm-thick active layers were fabricated using specially developed dry etching techniques. The RIE was optimized to allow deep low-damage etching and allowed reduction of contact resistivity of etched layers (RC
Taiichi OTSUJI Shin NAKAE Hajime KITAMURA
This paper describes the numerical analysis for terahertz electromagnetic-wave oscillation/detection properties of plasma-wave field-effect transistors (PW-FET's) and their applications to future smart photonic network systems. The PW-FET is a new type of the electron device that utilizes the plasma resonance effect of highly dense two-dimensional conduction electrons in the FET channel. By numerically solving the hydrodynamic equations for PW-FET's, the plasma resonance characteristics under terahertz electromagnetic-wave absorption are analyzed for three types of FET's; Si MOSFET's, GaAs MESFET's, and InP-based HEMT's. The results indicate that the InP-based sub-100-nm gate-length HEMT's exhibit the most promising oscillation/detection characteristics in the terahertz range with very wide frequency tunability. By introducing the PW-FET's as injection-locked terahertz-frequency-tunable oscillators and terahertz mixers, a new idea of coherent heterodyne detection utilizing terahertz IF (intermediate-frequency) bands is proposed for the future smart photonic network systems that enable real-time adaptive wavelength routing for add-drop multiplexing. The plasma resonance of PW-FET's by means of different frequency generation based on direct photomixing is also proposed as an alternative approach to injection-locked terahertz oscillation. To realize it, virtual carrier excitations by the polariton having photon energy lower than the bandgap of the channel is a possible mechanism.
Kiyoshi HAMAGUCHI Yozo SHOJI Hiroyo OGAWA Yasutake HIRACHI Seiji NISHI Eiichiro KAWAKAMI Eiji SUEMATSU Toshiya IWASAKI Akira AKEYAMA Youichi SHIMOMICHI Takao KIZAWA Ichiro KUWANA
The design and performance of a millimeter-wave video transmission system using 60-GHz band for indoor broadcasting-satellite (BS) signals transmission is presented. This system can transmit multiple video signals such as broadcasting signals and user-oriented signals to a television set indoors. To minimize the local oscillator's frequency offset and phase-noise effects, the system uses a remote-heterodyne scheme. Based on the concept, the system is developed to meet required carrier-to-noise-power-ratio (CNR) and 3rd-order intermodulation (IM). The BS transmission was experimentally done by using the transmitter and receiver setup. The results are very promising and show the feasibility of the system.
Hiroyuki TSUJI Hiroyo OGAWA Mitsuru HIRAKAWA Yoji OKADA Norichika OHMI Noriyuki TAGO
We describe a new system for high-speed wireless access systems between base stations and mobile terminals. In the proposed system, the base station has an array antenna and tracks mobile terminals by using a new tracking algorithm. A radio-on-fiber technique is used to simplify and miniaturize the components of the base station. Estimating the direction-of-arrival of the signals from a mobile terminal is important in implementing the proposed system. We propose a new tracking algorithm that uses directions-of-arrival, angular velocities of mobile terminals, and scatter modeling in multipath communications channels to improve the tracking performance. We also developed experimental equipment to demonstrate the feasibility of the proposed millimeter-wave broadband wireless access system and the efficiency of the tracking algorithm using an array antenna system. In this paper, we describe our system and present a new approach for tracking mobile terminals, which is the key feature of the system. We also discuss our simulation and experimental results.
Kazuaki TAKAHASHI Ushio SANGAWA Suguru FUJITA Michiaki MATSUO Takeharu URABE Hiroshi OGURA Hiroyuki YABUKI
We propose a three-dimensional structure on a planar substrate employing micromachining technology. A low-loss suspended structure incorporating a BCB membrane employing deep trench etching technology has been newly proposed. A micromachined suspended line structure using BCB membrane film enables us to realize a low loss planar resonator, which achieved an unloaded quality factor (Q-factor) of more than 280 at 60 GHz. We design low-loss filters and antennas built into silicon in a 60 GHz band. A low-loss filter realizes an insertion loss of 1.0 dB at 60 GHz and a patch antenna obtains a 3% bandwidth. In addition, we demonstrate a 60 GHz receiver front-end IC incorporating the planar filter and the antenna, and obtain good results. These techniques enable us to integrate various functions into a compact package even in millimeter-wave bands.
Toshio ISHIZAKI Toshihiro TERAOKA Koichi OGAWA
Cost down of millimeter wave components, especially antenna duplexer, is a key for spreading millimeter wave communication systems. An excellent cost-performance antenna duplexer is proposed. It consists of two E-plane filters and a wave-guide circulator. The performance fluctuations due to manufacturing accuracies are studied by simulations and experiments. These results are very useful for cost-down of the practical duplexer without performance degradation.
Kaoru SUDO Akira AKIYAMA Jiro HIROKAWA Makoto ANDO
Rectangular/circular-to-radial waveguide tra-nsformers through a ring slot have been proposed for the feeder of radial line slot antennas (RLSAs) in millimeter wave application. Rotating electric modes are excited by a set of ring slot and perturbation dog bone slot. Basic operation is observed in 12 GHz band. Concentric array radial line slot antennas fed by these transformers are fabricated and the antenna gain of 26.9 dBi with the efficiency more than 60% is measured. The applicability for millimeter wave is verified for 38 GHz band RLSA fed by the rectangular waveguide. The measured gain of the antenna is 22.5 dBi with the efficiency of 53% with the diameter of 46mm and 26.4 dBi with 61% with the diameter of 66mm.
Naoko ONO Keiichi YAMAGUCHI Minoru AMANO Masayuki SUGIURA Yuji ISEKI Eiji TAKAGI
The authors have developed V-band high electron mobility transistor (HEMT) MMICs adopting benzo-cyclo-butene (BCB) thin-film layers on GaAs substrates. Since the BCB thin-film layers, which can change the thickness of arbitrary parts on a circuit, are used for these MMICs, both a thin-film microstrip (TFMS) line, offering the advantages of great flexibility in layout and small size, and a coplanar waveguide (CPW), offering the advantage of low loss, can be used according to the purpose of the MMIC. Here we introduce the four types of V-band MMICs that we fabricated: low noise amplifier (LNA), mixer, voltage controlled oscillator (VCO), and power amplifier (PA). The optimum transmission lines were chosen from the TFMS line and the CPW for these MMICs. Miniaturization of the LNA MMIC and the mixer MMIC were attained by adopting the TFMS line, whereas adoption of the CPW enabled the VCO MMIC to achieve high performance. These results indicate that it is important to choose the optimum transmission line according to the purpose of the circuit function for each MMIC. It was confirmed that these newly developed MMICs using the BCB thin-film dielectric layers are attractive for millimeter-wave applications.
Yasushi SHIZUKI Ken ONODERA Fumio SASAKI Kazuhiro ARAI Hiroyuki YOSHINAGA Juichi OZAKI
A compact MMIC power amplifier which delivers P1dB of 25.8 dBm (380 mW) at 40 GHz has been developed. To make the chip width narrower, only one unit block using two parallel HEMTs is applied for a power stage. For achieving broadband interstage matching when using wide gate-width unit devices in the power stage, a new configuration of a unit block which contains a shunt capacitance is proposed.
Kazuya NISHIHORI Shigeru WATANABE Fumio SASAKI Kazuhiro ARAI
A 15-50 GHz-band GaAs MMIC variable attenuator has been developed for microwave and millimeter-wave wireless communications systems. The attenuator employs a balanced distributed configuration using shunt connected HEMT's in order to realize a broadband operation, a low insertion loss and a good impedance matching with simple control bias scheme. The MMIC was fabricated with a pseudomorphic HEMT device technology. It has exhibited an insertion loss as low as 1.6 dB with an attenuation control range as wide as 21 dB at 26 GHz. It has also shown a good linearity of an input power of more than 12 dBm at 1-dB compression point and that of 26.3 dBm at a 3rd-order intercept point.
This paper proposes a multisegment dielectric resonator (MSDR) placed on a slotline for millimeter-wave filter applications. The MSDR structure, including a rectangular dielectric lump and a thin low-dielectric insert, is quite useful for adjusting the coupling between the slotline mode and the resonant mode, leading to improve the filter performances. In addition, by tuning dimensions of the MSDR, a sharp and clear notch response can be designed in the transmission parameter. We have demonstrated the filter characteristics both theoretically and experimentally, and showed the practical procedure for the design of MSDR filters.
Yoshiro TOMABECHI Yoshinori KOGAMI Mari MATSUBARA Kazuhito MATSUMURA
Using a point matching method, we have numerically analyzed resonance frequencies and unloaded Q factor of whispering gallery modes in a millimeter wave region that are well known as an intrinsic mode of a dielectric disk resonator. We express field distributions of the resonance modes by a summation of spherical waves. Tangential electromagnetic fields inside the disk are matched to those outside the disk at appropriate matching points on a boundary. As the result, a 4N
Mitsuyoshi KISHIHARA Isao OHTA Kuniyoshi YAMANE
The present paper treats the analysis and design method of the (H)NRD guide and E-plane rectangular waveguide integrated structures on the basis of the transverse resonance technique. The analysis is made by assuming a resonant cavity short-circuited at appropriate reference planes and considering the cavity as a waveguide discontinuity problem in the transverse direction. The resonant lengths are determined from the transverse equivalent circuit, and the scattering parameters are calculated from the lengths. We analyze (H)NRD discontinuities and design two types of HNRD guide to E-plane waveguide transitions and a directional coupler composed of HNRD and E-plane waveguide. The theoretical results are in good agreement with results calculated by an EM-simulator.
Futoshi KUROKI Satoru SHINKE Tsukasa YONEYAMA Hiroya SATO
Although TE0nδ mode ceramic resonators are usually used at centimeter frequencies, they have difficulty in making wide-band band-pass filters in the millimeter-wave region due to the weak coupling factors between TE0nδ mode resonators and input/output waveguides. In order to overcome such difficulty, a band-widening technique of the ceramic resonator loaded band-pass filter has been proposed. The EHnmδ modes were regarded as spurious modes so far, but it is clear that the coupling factors are larger than those of the TE0nδ modes from the results of experimental considerations in this paper. By using the EH11δ mode ceramic resonators, 5-pole, 1 dB Chebyshev ripple NRD guide band-pass filter has been fabricated for the applications to broad-band millimeter-wave communication systems at 60 GHz. The filter has great advantages such as the wide pass-band beyond 2 GHz and low excess insertion loss of less than 0.3 dB.
A power combining technique using a Fabry-Perot resonator with many more active devices is investigated. The Fabry-Perot power combiner consists of two mirrors with a circular groove mounted with the active devices. The power combiner has an axially symmetrical structure and operates at an axially symmetrical TEM01n mode so that uniform device-field coupling required for perfect power combining can be realized. By numerical calculation using the boundary element method, it was shown that high combining efficiency can be obtained when the active devices are mounted in the circular groove of larger radius on either of the two mirrors. In experiments at X-band, power combining efficiency over 90% was obtained for the case of twelve devices on either of the mirrors and the output powers of the twenty or twenty-four devices on both the mirrors were almost perfectly combined.
Yoshinori KOGAMI Yosuke SATO Kazuhito MATSUMURA
The millimeter wave filter using two whispering-gallery mode dielectric disk resonators is presented in this paper. The coupling coefficients of dual disk resonators and the external Q values of the single resonator excited by a dielectric waveguide are investigated theoretically and experimentally. A 2-stage bandpass filter which is designed at the center frequency of 69.85 GHz with a bandwidth of 500 MHz shows a low-loss property of 1.8 dB insertion loss.
The boundary integral equation (BIE) on interior walls with surface impedance conditions is implemented to the iterative physical optics method and how to treat the singularities involved in the BIE of an impedance cavity is described. Singular integrals over a rectangular region can be represented by simple elementary functions.
Minoru YAMADA Shunsuke YAMAMURA Takaharu OKAMOTO
Characteristics of the optical feedback noise in semiconductor lasers under superposition of the HF (High Frequency) current were experimentally examined and theoretically analyzed. The feedback noise was mostly suppressed by superposition of HF current, but still remained when frequency of the HF current coincided with a rational number of the round trip time period for the optical feedback in experimental measurement. Theoretical analysis was also given to explain these characteristic based on the mode competition theory of the semiconductor laser.
This paper describes an electromagnetically coupled microstrip divider that provides high output port isolation and DC cutting. The device consists of a parasitic resonator placed above microstrip patch resonators, achieving tight coupling for both input and output ports. FDTD simulation and measurements reveal that the device has a high isolation between output ports. Equal and unequal 2-way and 3-way power dividers are presented in this paper.
Takao MYONO Akira UEMOTO Shuhei KAWAI Eiji NISHIBE Shuichi KIKUCHI Takashi IIJIMA Haruo KOBAYASHI
This paper presents improved versions of three-stage positive-output and two-stage negative-output Dickson charge-pump circuits which are intended to replace switching regulators in video-product CCD driver applications (where 12 V and -6.5 V are needed), and are designed and fabricated in a custom CMOS process. From a power supply Vdd of 4.0 to 5.5 V, the positive charge pump generates a positive output voltage of greater than 3.9Vdd, while the negative charge pump generates a negative voltage of greater than -1.9Vdd, both with efficiencies of greater than 94% at 2 mA output currents.
Shinichiro NISHIZAWA Wolfgang SPREITZER Hans-Oliver RUOSS Friedrich M. LANDSTORFER Osamu HASHIMOTO
An efficient numerical source model is proposed to calculate the induced current densities in the human body from low-frequency inhomogeneous magnetic fields emitted by electronic devices. Due to the complex geometrical structure of electronic devices (e.g. household appliances, power tools), an efficient equivalent source model based on magnetic elementary dipoles is used instead of the real device or the approximated source model (current loop). Subsequently, the validity of the method proposed is confirmed.
Junichi NAKAYAMA Toyofumi MORIYAMA Jiro YAMAKITA
A periodic approach introduced previously is applied to the TM wave scattering from a finite periodic surface. A mathematical relation is proposed to estimate the scattering amplitude from the diffraction amplitude for the periodic surface, where the periodic surface is defined as a superposition of surface profiles generated by displacing the finite periodic surface by every integer multiple of the period