May19, 2022

To whom it may concern,
Company: Tamagawa Holdings, Co., Ltd.
Representative: President, Toru Masuzawa(Tokyo Exchange Standard Market: Code: 6838)
Contact: Management Planning Division, Kana Yamauchi
Tel: 03-6435-6933

Notice on Success of Development of the Next Generation High-frequency
Oscillator Using Miniature Atomic Clock
Please be informed that we have succeeded in development of the next generation high-frequency
oscillator by embedding high-frequency crystal oscillator (*1) into the small atomic clock with cooperation ofTohoku University.
1. BackgroundAs announced in “Notice on Commencement of Joint Research with Tohoku University (Sendai City,Miyagi Pref.)” dated February 14, 2019, we have proceeded with the joint research with the researcher
Yasubumi Furuya / Tohoku University, Micro System Integration Center (former specially-appointedprofessor) as the research representative for the research and development of optimizing device control /monitoring system of surplus power, which is expected to be used in the natural energy (solar, wind,biomass, hot spring heat, etc.) field.
In addition, as announced in “Commencement of Research on Application Using a Miniature Atomic
Clock and Atomic Clock” dated July 6, 2020, we have also been proceeding with the joint research of theapplication using the miniature atomic clock and atomic clock with Professor Takahito Ono of School ofEngineering, Tohoku University as the research representative.
With support in both joint researches, etc., we have proceeded with consideration of low consumption
high-frequency oscillator, which is the core of high-frequency optic/wireless communication devices in thenext generation communication.
2. About this development
With the perspective of Society 5.0 and post Covid-19 world, while digital transformation (DX) of thesociety and industry is accelerated, greater capacity and further sophistication are currently expected in thecommunication infrastructure which is the platform to connect tremendous amount of data with people andthings as the contact point.
Atomic clocks used for the satellites, planetary exploration spacecrafts and communication base stations,etc. synchronize GPS (Global Positioning System) signals with UTC (Universal Time Coordinated) whenused as clock synchronization and can further reduce delay of transmission and reception time of the signals
between multiple base stations, etc. and between terminals. For the conventional atomic clocks, 10MHz
quartz crystal is used for VCO (voltage controlled oscillator (*2)) which transmits the reference clock signals,of which frequency is low compared to the recent 5G/6G high-frequency communication.
We have developed the high-frequency oscillator (Figure 1) with 640MHz quartz crystal embedded, which
has the property of temperature stability up to higher frequency, and succeeded in making the reference
clock frequency as 64 times as the conventional frequency.

This enables highly delicate high-frequency

communication with controlled jitter noise created by frequency drift.

VCO

(a)

(b)

(c)
Figure 1. Principle of the developed high-frequency oscillator and measurement result of phase noise of
the high-frequency oscillator for 5G/6G measured with frequency analyzation equipment(a) Explanation of CPT(Coherent Population Trapping) resonance which is quantum-optical phenomenon.
Energy between the ground levels has extremely stable property specific to atom. In case of 87Rb, it
is 6.83GHz if converted as frequency, and the stable clock is created by converting such energydifference into electric signals with laser to make oscillation clock of quartz crystal.
(b) Outlined block diagram of high-frequency oscillator using the voltage controlled oscillator of highfrequency oscillation. It is the design compatible with high-frequency communication by using crystal
oscillator of which basic mode is 640MHz, 64 times as high as the conventional 10MHz for VCO which
extracts the reference electric signals.
(c) 8.7 femtosecond, the world’s top class was achieved for RMS jitter noise (12 kHz – 20 MHz) from thephase noise measurement (Vertical axis: Noise ratio [dB], Horizontal axis: Frequency [Hz]).

3. Future approaches
With this development as the starting point, we will accelerate development of the communication devicesof high-frequency bandwidth which is essential for realization of the social base construction to unify thegovernment-promoted next generation communication / digital high-speed processing technology (highlyaccurate automatic driving, robot control, higher-security electronic payment, etc.) and digital rural city(smart city) conception and contribute to further building of safety and reliability of the next-generationinfrastructure.

<Terminology>*1: A quartz crystal is one of the active elements that cause oscillation of high frequency accuracy by using
the piezoelectric effect of crystal (quartz). It is the essential part for electronics of the present time suchas quartz clock, wireless communication, computer, etc.
*2: VCO stands for voltage controlled oscillator.
See Figure 1.
【Technical inquiries】
Management Planning Division: Nishino
Access the inquiry form below.
https://www.tmex.co.jp/tech_inq/

An oscillator that controls oscillation frequency by voltage.