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Transphorm and Fujitsu Integrate Their GaN Businesses

The Business Deal
Transphorm, Fujitsu Limited and Fujitsu Semiconductor recently announced that they are planning on combining their gallium nitride (GaN) semiconductor businesses.  Under the terms of the deal, Fujitsu Limited and Fujitsu Semiconductor will bundle their GaN design and development assets as well as their GaN power device intellectual property rights into a new company.  They will then make an investment in Transphorm using the newly formed company’s shares, receiving in return shares of equal value in Transphorm.  The two Fujitsu companies will also invest an additional undisclosed amount of cash in Transphorm and will contribute in a management capacity as minority shareholders in Transphorm.  The resulting structure will make the newly formed GaN company a wholly owned subsidiary of Transphorm.  Fujitsu Limited and Fujitsu Semiconductor employees, including 25-30 engineers, who currently work in the above mentioned power devices business will be reassigned to the new subsidiary of Transphorm.  After the transaction, Fujitsu Semiconductor’s Aizu-Wakamatsu plant, will be under exclusive contract with Transphorm to handle wafer processing. Transphorm’s GaN power devices are used in motor drives, power supplies, solar inverters, and electronic vehicle motor inverters, where high speed switching at high voltages is used to convert available DC voltages to the necessary AC voltages required by the particular application.

Referring to the agreement, Haruki Okada, President of Fujitsu Semiconductors said,

“Fujitsu Limited and Fujitsu Semiconductor will establish a new company in Japan for the GaN power device business and will transfer to the new company their combined design and development assets as well as intellectual property rights in GaN power devices. After the integration, Transphorm will continue R&D work at both its prototyping line in the US as well as Fujitsu Semiconductor’s Aizu-Wakamatsu plant, which will be under exclusive contract with Transphorm to handle wafer processing. Transphorm and Fujitsu Semiconductor intend to build a global market by generating synergies from bringing together their marketing, customer support and applications development capabilities.”

The Technology

Dr. Umesh Mishra

GaN transistors have perhaps their most prominent consumer application so far in high brightness LEDs.  Transphorm’s co-founders Umesh Mishra, and Primit Parikh both hail from Nitres Inc. an LED startup that has since become a part of Cree Inc.  Prior to their industry work Mr. Parikh and Dr. Mishra both hail from UCSB where Dr. Mishra is still a professor of electrical engineering and leads the Gallium Nitride research group there.

Some of the benefits of GaN transistors vs. Si MOSFET are summarized in a research paper[pdf], “High-Frequency, GaN Diode-Free Motor Drive Inverter with Pure Sine Wave Output” by Wu, Kebort, Guerrero, Yea, and Honea of Transphorm, and Shirabe, and Kang of Yasakawa America originally presented at PCIM Europe 2012 in Nuremberg, (the copy linked to here is from   The authors point out that a GaN transistor exceeds the performance of comparable Si MOSFETs in terms of “on” resistance, switching speed and parasitic capacitances.  They also point out that the GaN device is also capable of working in reverse conduction mode with little reverse recovery charge (Qrr).  This allows the device to be used in high-frequency, hard-switched bridge topologies for inverters.  Due to its low Qrr characteristics, the GaN transistor can be used without the freewheeling diode between gate and source required for Si MOSFETs, reducing the component count.

The authors also demonstrate that because the GaN device can be switched at higher pulse width modulation (PWM) frequencies, it generates a more pure sine wave output with fewer high frequency harmonic distortions.  In motor drivers, these distortions lead to hysteretic heat generating losses in the magnetic cores of the motor.  Consequently, lower distortions in a motor’s power inverter input leads to more efficient longer lasting motors.

If you’d like to learn more about inverter technology in general, check out this set of notes[pdf] from the MIT openware course on power electronics.

The Investors
In addition to Fujitsu Limited and Fujitsu Semiconductor, several other investors have taken an interest in Transphorm as can be seen in the investor logo chart taken from Transphorm’s team page.

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One Response to “Transphorm and Fujitsu Integrate Their GaN Businesses”

  1. San Kun Says:

    Nice Article

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