Basic Information

Division of Computer Engineering
Professor, Dean of School of Computer Scirnce and Engineering
Web site


Courses - Undergraduate
CSE Exercise I, Semiconductor Devices, Electronics
Courses - Graduate
SYC01 MOS Device Modeling for VLSI Design


Design of Analog and Radio Frequency (RF) Integrated Circuits for Wireless Communication Systems
Educational Background, Biography
March 1975: Graduated from Aizu High School, Fukushima, Japan
March 1979: B.S. in Applied Physics, Tohoku University, Japan
March 1981: M.S. in Applied Physics, Tohoku University, Japan
April 1981: Entered Nippon Telegraph and Telephone Public Corporation (Now NTT)
July 1987: Research Engineer, NTT LSI Laboratories
Feb. 1993: Senior Research Engineer, NTT Radio Communication System Laboratories
Feb. 1995: Senior Research Engineer, Supervisor, NTT LSI Laboratories
April 1998: Senior Research Engineer, Supervisor, Research Group Leader, NTT System Electronics Laboratories
Sep. 2001: Ph.D. in Electronic Engineering, Tohoku University, Japan
March 2006: Left NTT
April 2006: Full Professor, School of Computer Science and Engineering, University of Aizu
From April 2012 to March 2016: Served as Director General of the Department for Student Affairs
Nov. 2017: Received The 31st Radio Engineering and Electronics Association Award
From April 2018 to March 2020: Served as Director General of the Department for Student Affairs
From April 2020: Dean of School of Computer Science and Engineering
Current Research Theme
Design of Multi-Band and Multi-Mode RF Transceivers suitable for Software-Defined Radios
Key Topic
CMOS Analog Integrated Circuits, CMOS RF Integrated Circuits (RFIC), RF Transceiver, Wireless Communication, Software-Defined Radios, Multi-Band, Multi-Mode
Affiliated Academic Society
IEEE, IEICE, Senior member of IEEJ


1. Listening to live music performances
2. Voice training
3. Muscle training
4. Amateur radio operation (from 12 years old): Amateuer First-Class Radio Operator (2018), JA7IIX
School days' Dream
1. Electronics engineer
 When I was 8 years old, I made a germanium (Ge)-diode radio-receiver and could hear real AM radio programs. This simple experience made a great impact on my career. Then, this dream became the reality.
2. Airline pilot
Current Dream
1. To foster venture companies conducting "LSI design" in my hometown Aizu-Wakamatsu City or peripheral areas
2. To learn the "Bel Canto" singing method in Italy
Better be the head of a dog than the tail of a lion. (鶏口牛後)
Favorite Books
1. Harmonics (Akikazu Nakamura, Shunjusha)
 A bamboo-flute (Shakuhachi) player, who graduated from School of Engineering, Yokohama National Univ., shows spectrum-analysis results of various music sounds: Familiar applications of Fourier analysis.
2. Dr. Euler's Fabulous Formula: Cures Many Mathematical Ills (Paul J. Nahin, Nippon Hyoron Sha) [Japanese translation]
 This book describes various stories related to Euler's formula in complex number theory. Dealing with issues of electrical and communication engineering, it also gives interesting viewpoints to engineers.
Messages for Students
As mentioned in "Favorite books", basic mathematical theories are indispensable in analyzing familiar phenomena and building practical devices.
Publications other than one's areas of specialization
Relay Eassay 52

Main research

Software-Defined Radios

In these days, wireless communications are rapidly expanding worldwide and each person has a cellular phone. Several other wireless systems such Wireless LAN, Bluetooth, one-segment broadcasting, and GPS functions cab be integrated in a one terminal. However, these integration will have a limitation in the near future. So, software-defined radio (SDR) technology is proposed to overcome the limitation. Downloading application programs, an SDR terminal can work in different wireless systems. We are studying on integrated circuits suitable for implementing SDRs.

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Demand-addressable Sensor Network: for Demand-driven Large-scale Sensor Network

The aim of this research project is to construct a wide-area sensor network that interprets users’ abstract sensing demands. The network then finds the sensors that hold the data which satisfies the demand, mashes up the collected data within the network along with useful information from other systems, and finally enables the user’s terminal to display it in real time. The sensor network itself has an environmental adaptability that allows each sensor node to consider its surroundings and the user-issued requests, and which will then dynamically change its role to actively acquire the desired sensing data autonomously.

Related link:


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Dissertation and Published Works

[1] T. Tsukahara, "A High-Precision Quadrature Modulator Using a Fully-Differential CMOS Flip-Flop Phase-Shifter Suitable for the Next-Generation RF Transceivers," 2020 IEEE Int'l Symposium on Radio-Frequency Integration Technology (RFIT2020), WE3B-2, pp. 41-43, Sept. 2-4, 2020, Hiroshima, Japan. (Invited)
[2] S. Takara and T. Tsukahara, “Design of a Dual-LO Switching Quadrature Modulator Using a Flip-Flop Phase-Shifter,” IEEJ Transactions on Electronics, Information and Systems, Vol. 139, No. 1, pp. 87-88, Jan. 2019. => Mr. S. Takara received the "Excellent Paper Award" from Tohoku Branch Chair of IEE Japan (Denkigakkai) on April 22, 2020.
[3] T. Tsukahara, R. Ito, and K. Arimura, “Complex Signal Processing Used in Modern RF Transceivers,” 2015 IEEE Int’l Symposium on Radio-Frequency Integration Technology (RFIT2015), TH4A-1, pp. 100-102, Aug. 26-28, 2015, Sendai, Japan. (Invited)
[4] T. Tsushima and T. Tsukahara, "Design of Low-Voltage High-Precision Complex Quadrature Modulators," The 17th Workshop on Synthesis And System Integration of Mixed Information Technologies" (SASIMI 2012), R4-9, pp. 476-481, March 9, 2012 Beppu, Japan. [Refereed]
[5] T. Tsukahara, T. Tsushima, and H. Ito, "Evolution of Transceiver Architectures toward Software-Defined and Cognitive Radios," 2010 Int'l Conference on Solid State Devices and Materials (SSDM), pp. 99-100, Tokyo, Japan, Sept. 22, 2010. (Invited)
[6] T. Tsukahara, "Design of CMOS RF Circuits," MARUZEN, Nov. 30, 2009, (ISBN: 978-4-621-08203-4). [Book]
[7] T. Tsukahara, "RF CMOS Circuits- Overview and Perspective," 2007 Int'l Conference on Solid State Devices and Materials (SSDM), pp. 752-753, Sept. 2007 (Invited)
[8] J. Kodate, T. Douseki, T. Tsukahara, T. Okabe, and N. Sato," Practical High-Resistivity Silicon-on-Insulator Solution for Spiral Inductors in Radio-Frequency Integrated Circuits," Jpn. J. Apply. Phys., vol. 44, no. 8, pp. 5987-5993, Aug. 2005.
[9] A. Yamagishi, M. Ugajin, and T. Tsukahara, "A 2.4-GHz PLL Synthesizer for a 1-V Bluetooth RF Transceiver," IEICE Trans. Electron., vol. E87-C, no. 6, pp. 895-900, June 2004.
[10] M. Ugajin, J. Kodate, and T. Tsukahara, "A 1-V 2.4-GHz Downconverter for FSK Wireless Applications with a Complex BPF and a Frequency Doubler in CMOS/SOI," IEICE Trans. Electron., vol. E87-C, no. 6, pp. 888-894, June 2004.
[11] M. Ugajin, A. Yamagishi, J. Kodate, M. Harada, and T. Tsukahara, "A 1-V CMOS SOI Bluetooth RF Transceiver Using LC-Tuned and Transistor-Current-Source Folded Circuits," IEEE J. Solid-State Circuits, vol. 39, no. 4, pp. 569-576, April 2004.
[12] A. Yamagishi, T. Tsukahara, and M. Muraguchi, "An 85-Mbit/s DQPSK MODEM-LSI using a ROM Storage Capacity Reducing Technique Based on Phase Plane Symmetry," IEICE Trans. Electronics, vol. J86-C,no. 8, pp.845-852, Aug. 2003.
[13] T. Tsukahara, J. Kodate, M. Harada, M. Ugajin, and A. Yamagishi, "RF-CMOS Circuits Technologies and Future Trends," IEICE Trans. Electronics, vol. J86-C,no. 7, pp. 674-686, July 2003. (Invited paper)