Bi-GaN bi-directional GaN HEMTs save space, increase efficiency  

According to Innoscience Technology, the bi-GaN series of bi-directional GaN HEMT devices saves space and facilitates fast charging without risk of reliability-limiting and dangerous rises in temperature. Both of these effects can sometimes be seen in traditional silicon devices when fast charging, said the company. 

The bi-GaN devices can be used inside phone handsets to control the battery’s charging and discharging currents. Silicon MOSFETs are conventionally used as power switches in mobile phones and this development marks the first time that protection based on GaN technology has been included in the phone itself rather than the circuitry incorporated inside the charger. 

Innoscience said that the bi-GaN HEMTs can save significant space on a mobile phone’s main PCB. The low RDS(on) means that the HEMTs do not have parasitic diodes and Innoscience’s BiGaN technology also means that a single Bi-GaN HEMT can be used to replace back-to-back connected NMOS MOSFETs in a common-source configuration to achieve bi-directional switching of the battery’s charging and discharging currents. This reduces on-state resistance by 50 per cent, chip size by 70 per cent and temperature rises by 40 per cent.

The first BiGaN device available on general release is the INN040W0488, a 40V bi-directional GaN-on-silicon HEMT. It is available in a WLCSP measuring 2.1 x 2.1mm. The chip supports bi-directional switching with on-state resistance as low as 4.8 mOhm. 

BiGaN is suitable for applications such as over-voltage protection circuits for smartphone charging, high-side load switching circuits and switching circuits for multi-power systems. Innoscience is also working to extend the bidirectional family to lower on-state resistance as well as to higher voltages.

At the recent UFCS Technical Seminar of the 1st Plug Conference of Guangdong, OPPO confirmed that it is using Innoscience’s Bi-GaN HEMTs inside handsets, making it the world’s first cell phone manufacturer using Bi-GaN as direct charging load switcher. The choice, according to OPPO, not only saves space inside the phone but also reduces the temperature rise of the phone during charging. This maintains a more comfortable temperature during fast charging, extends the possible duration of fast charging, and provides a better user experience. OPPO also announced that the Bi-GaN bi-directional technology will also be adopted in future volume production cell phone models. 

Innoscience is a GaN technology provider, delivering GaN power devices that can be used in diverse applications including cloud computing, electric vehicles (EV) and automotive, portable devices, mobile phones, chargers and adapters. 

In November 2017, Innoscience established a mass production, eight-inch wafer line for GaN-on-Si devices in Zhuhai, China and introduced a new facility in the Suzhou area in September 2020.

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