Time: 8:30-9:15，Oct.27, 2023，Friday
Prof. Minoru Fujishima
The 300 GHz band, one of the sub-terahertz bands, will be used for sixth-generation (6G) wireless communications. Since the contiguous 44 GHz band in the 300 GHz band has been identified for wireless communications, data rates in excess of 100 Gb/s are expected. Conventionally, compound semiconductors and SiGe with extremely high-frequency performance have been required to achieve sub-terahertz wireless communications. On the other hand, it is possible to realize transceivers that exceed fmax by using CMOS integrated circuits, which are advantageous for mass production. In this talk, first, the background of the use of sub-terahertz wireless communications, including the 300 GHz band, will be given. Next, the techniques for realizing sub-terahertz transceivers with CMOS integrated circuits will be described.
On the other hand, it has been believed that higher frequencies shorten the communication distance and are limited to short-distance communications. However, free-space optical communications with frequencies much higher than terahertz enable long-distance communications between satellites over distances of several thousand kilometers. This is because, theoretically, the carrier frequency does not affect the communication distance, provided that the equivalent isotropic radiated power (EIRP) of the transmission and the receiving antenna size are the same. On the other hand, to increase the frequency bandwidth for higher data rates and to ensure the required signal-to-noise ratio, the receive power must be increased. This is a major factor that shortens the communication distance. As a result, beamforming, which uses limited transmit power to increase receive power, is essential for wideband communications. Beamforming also improves power efficiency during transmission, thus reducing overall system energy consumption. In this talk, I would like to consider how the world would change if ideal terahertz communications could be realized.
Minoru Fujishima received his Ph.D. from the University of Tokyo in 1993, and after working as an assistant and associate professor at the University of Tokyo, he has been a full professor at Hiroshima University since 2009. He was a visiting professor at the Katholieke Universiteit Leuven, Belgium, from 1998 to 2000. He was formerly engaged in research on design and modeling of CMOS and BiCMOS circuits, nonlinear circuits, single-electron circuits, and quantum computing circuits, and is currently interested in research on ultrahigh-speed wireless communications using terahertz. He served as a distinguished lecturer of the IEEE Solid State Circuits Society, Chair of the IEEE Japan Council Chapter Operations Committee, and is currently President of the Electronics Society of the Institute of Electronics, Information and Communication Engineers. He is a fellow of the Institute of Electronics, Information and Communication Engineers, a senior member of the IEEE, and a member of the Japan Society of Applied Physics.