Department of Production Systems Engineering
National Institute of Technology, Hakodate CollegeUltra Low-Power-Consumption and Power SelfSufficiency Techniques for IoT systems
NameMasashi Nakatsugawa

Emailnakatsugawa@hakodate-ct.ac.jp

StatusProfessor
・The Institute of Electrical and Electronics Engineers
・The Institute of Electronics, Information and Communication
Affiliations
Engineers, Japan・Japan Society of Applied Physics
Keywords

Microwave engineering, low power consumption, and wireless power transmission

TechnicalSupport Skills

・ Designing and prototyping microwave and millimeter-wave circuits
・ Designing wireless communication and/or power transmission system
・ Wireless service area estimation with radio propagation simulations

Research Contents
The digital twin utilization technology is drawing great interests to realize the ICT-empowered society. It
reconstructs the real world into the virtual environment via IoT systems, simulates the future, and feeds its
outcome back to enrich our life. The reconstruction, however, requires tremendous data collection throughnetworks using a huge number of sensors, which results in the increase in the IoT system’s total energy
consumption. In order to solve this energy issue, we investigate ultra-low power consumption and power
self-sufficiency.
Ultra-low power consumption by optimal function assignments between digital and analog signal processing
Ultra-low power signal processing that utilizes analog signal processing in addition to digital signal
processing has been proposed. Any information in the real world needs digitization for digital signal
processing (DSP). Although DSP for the GHz band requires state-of-the-art DA/AD converters and highspeed processors with huge power consumption, phase control of GHz-band high-frequency signals can beachieved over 360° with an analog phase shifter (Fig. 1) by simply controlling the voltage of a variablecapacitor without consuming power (Fig. 2). The optimal assignments of the system functions between thedigital and analog domains, with which the analog functions can complement the high-load digital
functions, should reduce overall signal processing volume and power consumption of the entire system.

0-to-π analog
phase shifter0/θ digitalphase shifter

Chip size
Series transmission
line division

Pseudo transmission
line reactance circuit

Fig.1 0-to-360 degree analog phase shifter

Amount of phase change θ (degree)

Power self-sufficiency to ease installation conditions of IoT terminals and system advancement throughsimultaneous transmission of power and information
In supplying energy to IoT terminals, it is better if a large number of terminals are deployed without
restrictions on installation conditions. For this purpose, we consider techniques to free terminals from theconstraints of wired power supply, and to achieve power self-sufficiency by securing wireless andindependent energy sources. We investigate wireless power transmission and energy harvesting.
Furthermore, we do research on information/power simultaneous transmission in the wireless fashion toControl voltage in π-state V c （-V ）enhance system capabilities.
02502345200150100500f=12GHz

0 1 2 3 4 5Control voltage in 0-state V c （-V ）Fig.2 Phase shifter performance

Available Facilities and Equipment
Arbitrary Waveform Generator

Digital Oscilloscope

Digital multimeter

DC Power supply

Microwave circuit simulator1