Interview with Philip Zuk from Transphorm

  • Philip Zuk - Senior Vice President, Business Development and Marketing, Transphorm

everything PE interviewed Philip Zuk from Transphorm who drives the business development and marketing efforts for Transphorm's high-voltage GaN FET technology in high-power applications. Transphorm is a semiconductor company that is focused on producing transistors made from gallium nitride for use in switched-mode power supplies

Q. Can you give us a brief history of Transphorm? When was the company started, and what was the objective?

Philip Zuk: Transphorm was founded by Umesh Mishra and Primit Parikh in 2007 with the mission to bring next-generation power conversion products to market. The goal was to reduce energy dependencies by increasing energy efficiencies.

We built our company differently than other GaN manufacturers in our industry. We opted for d-mode (cascode – two switch normally off) instead of e-mode as we were able to achieve the desired performance as well as the industry’s highest reliability to date. And we were able to do that because we are a vertically integrated business - this allows us to innovate at every development stage: device design, EPI, fabrication, and application support. Plus, and this is important, we own our own epi…the “secret sauce” in GaN devices.

When we started, Gallium Nitride was an emerging technology with the inherent promise of dramatically increasing power efficiency and power density while reducing overall power system costs. Through Transphorm’s innovations, we’ve been able to prove that true. Our technology has been able to achieve 99% power efficiency, 50% higher power density, and up to 20% lower power system costs.

Our technology innovations have enabled us to release 5 generations of our GaN platform. The last two (Gen IV and Gen V) are part of the SuperGaN family which is better explained in a subsequent question. We have also demonstrated GaN’s first high current short circuit current limiter (SCCL) as well as 1200 V performance.

We are also heavily involved in exploring/pushing the boundaries of GaN in power applications. We work closely with government agencies and industry organizations to drive the GaN power conversion market forward. Over the last few years, we have expanded our GaN product development to include n-polar GaN, which is part of our EPI sales vertical. This technology can be used in RF and mm-wave applications (first announced in 2019, and then expanded on in 2021). We have the capability of producing GaN-on-Si, GaN-on-SiC, and GaN-on-Sapphire EPI wafers.

And, lastly, we were the first pure-play GaN manufacturer to go public. Today, we trade on the Nasdaq under TGAN.

Q. Can you tell us more about Transphorm’s product portfolio?

Philip ZukWe have one core GaN platform that crosses the power spectrum, setting us apart from other GaN power semiconductor companies. We cover the:

  • Widest range of power
  • Widest variety of standard/commonly used packages (PQFNXX and TO-XXX) 

We have the industry’s highest noise immunity threshold at 4 volts and the largest gate robustness at +/- 20 Vmax

We offer the industry’s only: 

  • 900 V GaN devices
  • 1200 V GaN devices (in R&D) 
  • 175C automotive-qualified devices 

These devices are supported with a comprehensive portfolio of design resources including evaluation kits and reference designs for various applications across various power levels. And, we have partnered with several key technology leaders on those design tools (ex: MicrochipDiodes Inc.Silanna Semiconductors, etc.) to simplify the development process for our customers.

Q. What is SuperGaN Technology? How is it different from other technologies available in the market?

Philip ZukThe patented SuperGaN technology refers to Transphorm’s most recent GaN platform generations (Gen IV and Gen V). When designing Gen IV, Transphorm’s engineering team drew on learnings from production ramps of previous products to simplify the GaN platform design while increasing performance. Additionally, the changes to Gen IV increased the platform’s manufacturability, thereby enabling the company to reduce costs to bring GaN device prices closer in line with those of Silicon devices (something the market wants). 

SuperGaN benefits include:

  • Increased Performance: A flatter and higher efficiency curve with an improved Figure of Merit (RON*QOSS) of approximately 10 percent.
  • Easier Designability: Increased simplicity of design-in by removing the need for a switching node snubber at high operation currents.
  • Enhanced Inrush Current Capability (di/dt): Removal of the switching current limits for the built-in freewheeling diode function in half bridges.
  • Reduced Device Cost: Simplified device assembly driven by design innovations and patented technology. 
  • Proven Robustness/Reliability: Devices generally offer a +/- 20 Vmax gate robustness and 4 V noise immunity that was first delivered by Transphorm’s Gen III devices. These ratings are currently the highest in the GaN device industry.

Q. What are the advantages of SuperGaN FET ICs over SiC MOSFETs

Philip ZukFirst, we do not manufacture GaN ICs (integrated circuits). We manufacture discrete GaN FETs.

Second, from our point of view, no two wide bandgap technologies are the same. When compared to SiC MOSFETs, Transphorm’s SuperGaN devices offer higher power efficiency, more operating power, lower crossover losses, lower temperature operation, stable threshold voltage across devices and temperature range, and simplified drive circuitry. 

                                   

                           

       

In short - we offer better power conversion with: 

  • Up to 38% power loss reduction at 9.2 kW
  • Approximately 20% lower junction (Tj) temperature with up to 2.8 kW increase in power
  • Highest combination of power and efficiency (12 kW/98.5% vs. 11 kW/98.3% and 9 kW/98.2%)

Q. Can you tell us more about Transphorm’s 900 V GaN FET Technology? What are its key features and applications?

Philip ZukWhile you asked about 900 V, I’d like to make sure you’re aware that we have continued to expand our power range with a 1200 V device that is currently in development.

We offer the industry’s only 900 V GaN device as of today. The TP90H050WS has a typical on-resistance of 50 milli-ohms with a 1000 V transient rating. It comes in a standard TO-247 package, making it easy to drive with any off-the-shelf driver power electronics engineers are used to working with.

                                                     

The device can reach power levels of 8 kW in a typical half-bridge while maintaining greater than 99 percent efficiency. Its figures of merit for Ron*Qoss (resonant switching topologies) and Ron*Qrr (hard switching bridge topologies) are two to five times less than those of common superjunction technologies in production - indicating highly reduced switching losses.

It provides higher breakdown levels for power systems used in renewablesautomotive, and various broad industrial applications. It is designed to be deployed in bridgeless totem-pole power factor correction (PFC), half-bridge configurations used in DC-to-DC converters and inverters. The ability to support these topologies at a higher voltage makes the 900 V device useful for various three-phase industrial applications, such as uninterruptible power supplies and automotive chargers/converters at higher battery voltage nodes.

Q. What is Cascode configuration? How it is different from the e-mode configuration? What are some uses cases?

Philip ZukCascode GaN can also be called two-chip normally-off GaN where it uses the native d-mode GaN, (simplest to manufacture and highest performing) with a robust and reliable low voltage silicon MOSFET (technology that has been around for decades). You can see a basic diagram of the d-mode and e-mode configurations below.

                          

Transphorm’s d-mode / cascode devices offer several advantages over e-mode GaN. 

  • Reliability: Our decision to manufacture cascode GaN was driven by reliability. We currently offer the highest reliability GaN devices on the market with a FIT (failure per billion hours) rate of < 0.1 with > 80B field operation hours. And that FIT rate is derived from device use in high-power applications as well as low-power ones. 
  • Designability: The d-mode configuration allows for simpler development end to end. You’ll note the drivability advantage below.

It’s also important to understand that our GaN FETs offer a minimum 8 V of headroom between the drive voltage and its +/- 20 Vgs Max for superior robustness and 4 V noise immunity - whereas e-mode is currently offering a 1 to 2 V maximum headroom to its 7 Vgs Max and 1.7 V noise immunity.

The platform configuration and its resulting Quality + Reliability also reduce the number of peripheral components required when designing with our devices. Whereas Transphorm GaN requires at a minimum only two additional parts; e-mode can require a minimum of 7 or more depending on whether the device is a discrete or IC. 

  • Drivability: Our GaN FET is available in standard PQFN and TO-XXX packages. We can use the TO-xxx packages due to our two-chip normally off configuration and achieve superior reliability as well as performance along with the designers being very familiar with the package. A major benefit of this design is that the GaN device is then driven by a standard off-the-shelf driver whereas e-mode is a custom package that requires custom drivers. This can cause development complexity and increased costs.

Q. Can you tell us more about your Bridgeless totem pole PFC GaN evaluation boards? What are its industrial applications?

Philip ZukWe offer three bridgeless totem-pole evaluation boards, one for 2.5 for and two at 4 kW. These evaluation boards show the true value proposition of GaN, which is greater than 99% efficiency. The bridgeless totem-pole topology has been around for decades but only now can be realized with the efficient operation of bi-directional current flow. Our evaluation boards have been designed using the dsPIC from Microchip, a global technology company well known for its micro-controllers and design environment. Combining Microchip’s dsPIC, Microchip,’s firmware and Transphorm’s highly reliable GaN FETs gives customers a head start on their own design and development of realizing the benefits of Transphorm GaN. This topology is deployed in various markets that use AC to DC power suppliers 500 W and greater.

Q. Can you us about the World’s first 175 C automotive-qualified GaN transistor? What are its key features and applications?

Philip ZukOur latest (third) AEC-Q101-qualified part is the SuperGaN TP65H035G4WSQA device. It is a 650 V FET with an on-resistance of 35 milli-ohms in a TO-247 package. As you noted, the device is automotive qualified to 175°C. This junction temperature is 25°C higher than what silicon MOSFETs qualify at and is a temperature rating yet to be achieved by any other GaN solution, some of which are only qualified to 125°C and 150°C. 

The device's key benefits include the:

  • Enables AC-DC, DC to DC, and DC to AC value
  • Increased power density
  • Reduced system size and weight
  • Overall lower system cost
  • Achieves increased efficiency in both hard- and soft-switched circuits
  • Easy to drive with commonly used off-the-shelf gate drivers
  • GSD pin layout high-speed high-speed design

These advantages benefit on-board chargers (OBCs), DC to DC converters, in-cabin inverse, and the future main traction inverters while also contributing to a larger battery range and faster charging. These four highlighted critical systems make battery electric vehicles (BEVs) not only drive but function properly and GaN plays a part in all.

Q. Who are your customers? What sectors or industries are they from?

Philip ZukTransphorm develops one core GaN platform that crosses the power spectrum. We are one of the only GaN power semiconductor manufacturers to be able to support a power range from 45 W to 10 kW+ today. We have publicly confirmed customers in the majority of industries below and can confirm we are working with customers in all of them.


Some recently announced customers include Phihong (65 W power adapters) and Nayuta (power storage for medical devices). Examples of other publicly announced customers can be found here: https://www.transphormusa.com/en/gan-technology/#customers

Q. What is your product roadmap for the next three years?

Philip ZukBeing that we are a vertically integrated company - where we own the supply chain from design, EPI, and fabrication - innovation is one of our strengths. We need to continue to innovate to satisfy our customers as they continue to innovate. We will continue to drive costs down and increase performance on our flagship 650 V technology. We will introduce new packaging options. And, we will add to the mix our latest short circuit capability along with our 1200 V technology.

About Philip Zuk

Philip Zuk drives the business development and marketing efforts for Transphorm's high-voltage GaN FET technology in high-power applications. He worked previously for Vishay (Siliconix) heading up their high voltage superjunction technology, Microsemi PPG running marketing efforts on their high voltage MOSFET, FRED diodes, IGBTs, and SiC efforts, Medallion Instrumentation Systems, and Fairchild Semiconductor. He has expertise in power supply designed systems and applications, high-power semiconductor devices, micro-controller-based systems, RFID, and project management. He holds an MBA (Hons) from I.H. Asper School of Business, University of Manitoba, a Bachelor of Science in Electrical Engineering, University of Manitoba, and an Electronic Engineering Technology Associate Degree, from Red River College. He holds 2 US patents a trade secret and has authored many technical and application papers.