A 60 GHz direct conversion transceiver which employs amplitude/phase imbalance cancellation technique is newly proposed. By using the proposed technique, the receive path of the transceiver achieves less than 0.2 dB of amplitude error and less than 3 of phase error at 60 GHz bands over a 10 GHz bandwidth, which relaxes the design accuracy required for baluns used in the transceiver. It also employs a simple and fast calibration algorithm to adjust the locking range of the divide-by-3 injection locked divider in the phase locked loop. Fabricated in 90 nm CMOS technology, the transceiver achieves a low power consumption of 230 mW in transmit mode and 173 mW in receive mode. The output spectrum of 1.76 Gsps π/2-BPSK/QPSK modulation shows the excellent distortion and spurious suppression that meet the IEEE802.11ad draft standard.

In this paper, we present the roles played by millimeter-waves in the realization of an Internet of Things (IoT) society. Millimeter-waves are becoming essential frequency resources, enabling ultra-high-speed wireless networks supporting massive data traffic and high-resolution sensor devices. Multiple antenna technologies such as phased arrays, sector antennas, and MIMO signal processing are key technologies for putting these into practical use. In this paper, various examples of integration of multi-antenna systems are shown, as well as demonstration on 60GHz-band millimeter-wave wireless access and 79GHz-band high-resolution radar. We also propose applications to ITS for an IoT society, combining millimeter-wave wireless access and radar sensors, and discuss technical issues to be solved in the future.

This paper presents a programmable wideband low pass filter (LPF) with Continuous-Time (CT)/Discrete-Time (DT) hybrid architecture. Unlike the conventional DT LPF, the proposed LPF eliminates sample & hold circuits, enabling to expand available bandwidth. The transfer function and the influence of the circuit imperfection are derived from CT/DT hybrid analysis. A prototype has been fabricated in 40 nm CMOS process. The proposed LPF achieves 2.5 GHz bandwidth by wideband equalization, which offers capacitance ratio (Cratio) and clock frequency (fCK) programmability. The proposed LPF occupies only 0.048 mm2 of active area.

In this letter we propose a new transmission technique to realize both high speed data transmission and high data quality by decreasing the difference in BER performance due to the phase difference of direct paths for 22 MIMO systems using spatial multiplexing in LOS environments.

Millimeter wave provides high data rates for Vehicle-to-Everything (V2X) communications. This paper motivates millimeter wave to support automated driving and begins by explaining V2X use cases that support automated driving with references to several standardization bodies. The paper gives a classification of existing V2X standards: IEEE802.11p and LTE V2X, along with the status of their commercial deployment. Then, the paper provides a detailed assessment on how millimeter wave V2X enables the use case of cooperative perception. The explanations provide detailed rate calculations for this use case and show that millimeter wave is the only technology able to achieve the requirements. Furthermore, specific challenges related to millimeter wave for V2X are described, including coverage enhancement and beam alignment. The paper concludes with some results from three studies, i.e. IEEE802.11ad (WiGig) based V2X, extension of 5G NR (New Radio) toward mmWave V2X, and prototypes of intelligent street with mmWave V2X.

Low-power technology for front-end GaAs ICs and hybrid IC (HIC) for a mobile communication equipment will be presented. For low-power operation of GaAs front-end ICs, new techniques of the intermediate tuned circuits, the single-ended mixer, dualgate MESFETs, and the asymmetric self-aligned LDD process were investigated. The designed down-converter IC showed conversion gain of 21 dB, noise figure of 3.5 dB, 3rd-order intercept point in output level (IP3out) of 4.0 dBm, image-rejection ratio of 20 dB at 880 MHz, operating at 3.0 V of supply voltage and 5.0 mA of dissipation current. The down-converter IC was also designed for 1.9 GHz to obtain conversion gain of 20 dB, noise figure of 4.0 dB, IP3out of 4.0 dBm, image-rejection ratio of 20 dB at 3.0 V, 5.0 mA. The up-converter IC was designed for 1.9 GHz using the same topology of circuit and showed conversion gain of 15 dB, IP3out of 7.5 dBm, and 1 dB compression level of -8 dBm with -20 dBm of LO input power, operating at 3.0 V, 8.0 mA. Another approach to the low-power operation was carried out by HIC using the GaAs down-converter IC chip. The HIC was designed for 880 MHz to show conversion gain of 27 dB, noise figure of 3.3 dB, IP3out of 3.0 dBm, image-rejection ratio of 12 dB, at 2.7 V, 4.5 mA. The HIC measures only 8.0 mm6.0 mm1.2 mm.

A new mm-wave IC, constructed by flip-chip bonded heterojunction transistors and microstrip lines formed on Si substrate, has been proposed and demonstrated by using MBB (micro bump boding) technology. Millimeter-wave characteristics of the MBB region has been estimated by electro-magnetic field analysis. Good agreements between calculated and measured characteristics of this new IC (named MFIC: millimeter-wave flip-chip IC) have been obtained up to 60 GHz band. Several MFIC amplifiers with their designed performances have been successfully fabricated.

This paper describes new millimeter-wave ICs based on flip-chip bonding using micro bumps on a low cost silicon substrate, named millimeter-wave flip-chip ICs (MFICs). They have significant advantages such as good performance, low cost and excellent flexibility in the active device selection which makes them superior to conventional monolithic microwave integrated circuits (MMICs). In order to demonstrate these advantages, a K-band front-end block for a broadband wireless communication equipment was designed and fabricated. This front-end block consists of four MFIC chips: a low noise amplifier (LNA), a down converter and two medium power amplifiers. These chips are designed to satisfy stable operation conditions using a simplified model derived for micro bump bonding (MBB). In experimental measurements; the LNA using heterojunction field-effect transistors (HFETs) had an 18 dB gain, the down converter using an HFET had a 9. 5 dB conversion loss, and two power amplifiers using heterojunction bipolar transistors (HBTs) had saturated powers of 13. 0 dBm and 11. 7 dBm, respectively. The performance for each of the developed ICs agreed with the designed values, and satisfied circuit requirements. These results show that the MFIC technique is a potential technology for manufacturing multi-functional millimeter-wave ICs.

This paper describes a new millimeter-wave hybrid integrated circuit (HIC) technology which applies a thin film multi-layered dielectric substrate and flip-chip bonding technology employing stud bump bonding (SBB). We have previously proposed and demonstrated a novel HIC structure, named millimeter-wave flip-chip IC, (MFIC), applying an excellent dielectric material of benzocyclobutene (BCB) thin film and flip-chip bonding. In this paper, an advanced thin film multi-layer process using non-photosensitive BCB was newly developed. Characteristics of the transmission lines and the built-in MIM capacitor within the multi-layered structure were discussed. Furthermore, stud bump bonding was newly adapted to the MFIC as a flip-chip method, and the millimeter-wave characteristics of the bumps were examined. Using these technologies, we demonstrate characteristics of a miniaturized 25 GHz down converter MFIC. Our newly proposed HIC structure enabled us to bring down chip size to less than 1/3 of our conventional structure. Finally, we discuss future possibilities for high performance multi-chip-modules (MCMs) using SBB technology as a further improved HIC for compact millimeter-wave radio equipment.

Millimeter-wave (mmw) frequency bands, especially 60GHz unlicensed band, are considered as a promising solution for gigabit short range wireless communication systems. IEEE standard 802.11ad, also known as WiGig, is standardized for the usage of the 60GHz unlicensed band for wireless local area networks (WLANs). By using this mmw WLAN, multi-Gbps rate can be achieved to support bandwidth-intensive multimedia applications. Exhaustive search along with beamforming (BF) is usually used to overcome 60GHz channel propagation loss and accomplish data transmissions in such mmw WLANs. Because of its short range transmission with a high susceptibility to path blocking, multiple number of mmw access points (APs) should be used to fully cover a typical target environment for future high capacity multi-Gbps WLANs. Therefore, coordination among mmw APs is highly needed to overcome packet collisions resulting from un-coordinated exhaustive search BF and to increase total capacity of mmw WLANs. In this paper, we firstly give the current status of mmw WLANs with our developed WiGig AP prototype. Then, we highlight the great need for coordinated transmissions among mmw APs as a key enabler for future high capacity mmw WLANs. Two different types of coordinated mmw WLAN architecture are introduced. One is distributed antenna type architecture to realize centralized coordination, while the other is autonomous coordination with the assistance of legacy Wi-Fi signaling. Moreover, two heterogeneous network (HetNet) architectures are also introduced to efficiently extend the coordinated mmw WLANs to be used for future 5th Generation (5G) cellular networks.

This paper presents the design and experimental evaluation of 60GHz small cell radio access based on IEEE 802.11ad/WiGig. The access point (AP) prototype used combines three RF modules with beamforming technology to provide 360° area coverage. In order to compensate for limited communication distance, multiple APs are employed to achieve wide area coverage. A handover algorithm suitable for IEEE 802.11ad/WiGig is employed to achieve flexible control of the cell coverage of each AP. As a proof of concept, a prototype system is set up at Narita International Airport and the capability of multiuser Gb/s wireless access is successfully demonstrated. In addition, the system behavior under stringent conditions is evaluated by load testing and throughput degradation due to co-channel and inter-channel interference is investigated.

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.

A millimeter-wave radio access system has a number of features that makes it appealing as one approach to broadband communications. However, for a millimeter-wave system to come into wide use, it must be miniaturized and the associated costs reduced. We have succeeded in realizing a compact 156 Mbps radio transceiver with a 38 GHz band optimizing RF architecture. We also adopted newly developed three-dimensional laminated MCMs using low cost plastic composite materials. It was confirmed in the initial experiments that this millimeter-wave wireless LAN equipment can cover a sufficient service area for broadband telecommunications in an indoor environment.

This paper demonstrates 300GHz terahertz wireless communication using CMOS transmitter (TX) and receiver (RX) modules targeting sixth-generation (6G). To extend communication distance, CMOS modules with WR-3.4 waveguide interface and a high-gain antenna of 40dBi Cassegrain antenna are designed, achieving 36Gbps throughput at a 1m communication distance. Besides, in order to support orthogonal frequency-division multiplexing (OFDM), a self-heterodyne architecture is introduced, which effectively cancels the phase noise in multi-carrier modulation. As a proof-of-concept (PoC), the paper successfully demonstrates real-time video transfer at a 10m communication distance using fifth-generation (5G) based OFDM at the 300GHz frequency band.

In this paper, we evaluate BER (bit error rate) performance and diversity gain when employing a transmission technique utilizing LC (Linear Combination) diversity using 2 time slots with QPSK channels in 2 2 MIMO (Multiple-Input Multiple-Output) spatial multiplexing systems by comparing it with the upper and lower bound on BER. This evaluation shows that this transmission technique realizes high diversity gain and high transmission rate in LOS (line-of-sight) and NLOS (non line-of-sight) environments.