Interview with Jin Zhao from Diodes Incorporated

  • Jin Zhao - Senior Vice President and General Manager, Analog Business Group, Diodes Incorporated

everything PE interviewed Dr. Jin Zhao from Diodes Incorporated who manages their Analog Business Group. Diodes Incorporated is a leading global manufacturer and supplier of high-quality application-specific standard products within the broad discrete, logic, analog, and mixed-signal semiconductor markets.

Q. Can you give us a brief history of Diodes Incorporated?

Jin Zhao: Diodes Incorporated was originally formed back in 1959, as a regional semiconductor trading company. Then, in the early 1990s, it began its transformation into a fully integrated manufacturing and distribution company. In 1996, Diodes started building up its manufacturing capacity in China and continued to expand its operations around the globe.

In 2005, Dr. Keh-Shew Lu became Diodes’ CEO and set up a series of ambitious growth goals for the company. The first of these goals was to achieve a $1 billion market cap, and this was reached in 2010. The next goal was to take the company’s annual revenues beyond $1 billion, which followed in 2017. The third goal, which he set in late 2017, was for Diodes to post a $1 billion gross profit by 2025, and this is something that the company is on track to attain within that timeframe.

A testament to Diodes’ success is that it has been profitable for 30 consecutive years. Its continued expansion has been through a combination of organic growth and well-judged acquisitions. Over the last two decades, the company has acquired Anachip Corporation (2006), Advanced Power Devices (2006), Zetex (2008), Power Analog Microelectronics (2012), BCD Semiconductor (2013), Pericom Semiconductor (2015), and TI’s Greenock wafer fab (2019). The most recent acquisitions have been Lite-On Semiconductor (2020) and onsemi’s South Portland wafer fab (2022).

Q. Can you tell us about your product portfolio? What types of products do you develop?

Jin Zhao: Diodes have an expansive product portfolio that covers discrete, analog, and mixed-signal devices. We can leverage industry-leading expertise in semiconductor processes and accompanying packaging technology, to address the engineering challenges that our customers face. Among the analog products that my business group produces are gate drivers, LED drivers, AC/DC converters, DC/DC converters, load switches, and LDO voltage regulators, plus signal chain products like ReDrivers for signal integrity and high-speed data switches, as well as numerous timing components too.

Q. Can you give us some more information about your power management portfolio? 

Jin Zhao: Diodes power management IC portfolio is seeing a great deal of commercial traction. In the last three years, its shipments have doubled. Through ongoing R&D investment, we have successfully brought products to market that offer real value to our customers, and this has resulted in significant market share gains - particularly in industrial and automotive applications. Among the new products we have introduced are high-voltage DC/DC converters and LDO voltage regulators up to 60 V, again focusing on industrial and automotive applications.

Q. What are the categories or segments within the power management portfolio that have been growing the fastest? What factors do you feel account for this growth?

Jin Zhao: We have seen considerable growth in demand for our power management products from the high-end consumer, home appliance, power tool, and automotive sectors. Bringing differentiated new products to market has fueled this demand upside. For example, about our DC/DC converter portfolio, in recent years, we have more than doubled the part numbers available - with input voltages of 5 V, 18 V, 32 V, 40 V, all the way up to 60 V now being addressed. The ongoing chip shortage situation and the need for OEMs to find alternative suppliers capable of supporting their volume requirements have helped to open up opportunities - adding to our list of customers. This has been most noticeable in regions like North America, Europe, and Japan.

Q. What are the major considerations required when developing compact power electronic products that deliver high power efficiency?

Jin Zhao: The need to increase power densities is continuing to have a huge influence on power device development. We must take into consideration both the semiconductor process and the packaging technology aspects of this. On the semiconductor side, low channel resistance (RON) and low gate charge (Qgd) will mean that power loss reductions can be made in terms of conduction power losses and switching power losses respectively. Higher switching frequencies are enabling reductions in output LC filter size and overall power solution size. These all come with trade-offs though, with improvements in one area causing deteriorations elsewhere. That is why a move from silicon to wide-bandgap technology (such as SiC and GaN) will be of such value, as it will enable major increases in power density to be realized.

Regarding packaging technology, flip-chip devices with exposed thermal pad-based packages can offer increased current capabilities and enhanced thermal performance. The use of integrated inductors will mean further size reductions and lead to greater power densities.

Q. What are synchronous buck converters? What are the key features of these converters? Where are these buck converters usually used?

Jin Zhao: A synchronous buck converter produces a regulated output voltage that is lower than its input voltage while delivering high levels of efficiency and only taking up a small amount of board real estate (thanks to the integration of both high-side and low-side MOSFETs, eliminating the need for external diode components). These devices are used in equipment that is targeted at a broad spectrum of different markets - including consumer, communications, computing, industrial, automotive, etc. Diodes offer an expansive array of high-performance buck converters with input voltages up to 40 V and output voltages down to 0.6 V being supported at different current levels.

Q. Can you tell us more about your wafer fabrication sites and design centers? Are all your products developed in your fabs? 

Jin Zhao: Diodes analog products are fabricated in multiple wafer fab sites around the world - both internally and externally via foundry partners too. We also have analog design centers situated at multiple locations globally, mostly in the USA and Asia. These are critical to our technical progression as a company, enabling us to introduce new products that have a significant market impact.

Q. Can you tell us more about your recent acquisition of onsemi's fab facility? What was the objective behind this move?

Jin Zhao: Diodes signed a definitive asset purchase agreement about onsemi's South Portland fab back in February this year and, the acquisition was completed in June 2022. The increased production throughput from this facility is well aligned with our strategic objective of substantial revenue growth and increased profitability. This wafer fab will provide Diodes with an additional 8-inch wafer fab capacity, enabling us to satisfy increased customer demands for our newly released analog products - including power management ICs, signal chain devices, and standard products for automotive and industrial segments.

Q. A number of your products are labeled as ‘Green’? What does this mean, and how is it different from standard RoHS certification?

Jin Zhao: In addition to Diodes’ products being compliant with EU Restrictions of Hazardous Substances directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) and 2015/863/EU (RoHS 3), which restrict the use of certain hazardous substances (such as lead) in electrical and electronic equipment, we also market halogen and antimony free ‘Green’ products too. We define these as containing <900 ppm bromine, <900 ppm chlorine (<1500 ppm bromine/chlorine total), and <1000 ppm antimony compounds.

Diodes’ data sheets declare the product-specific compliance levels accordingly. We also publish comprehensive and frequently updated Environmental Compliance reports with further details and references to international standards and directives.

Q. Can you give us more information about your ultra-high-power-density (UHPD) charging solution? How is it different from other charging solutions available in the market? 

Jin Zhao: Diodes are taking a holistic approach to its UHPD solutions, attending to all the different aspects that customers must consider when undertaking a charging system design. The active clamp flyback (ACF) topology employed balances elevated efficiency with minimal bill-of-materials (BoM) cost. 

Though ACF is not new to the industry, Diodes’ ACF power UHPD solutions are proving particularly effective at keeping BoM costs down, through the inclusion of highly integrated low standby-power PWM controllers, ACF synchronous rectification controllers, and USB PD3.0/3.1 SRP/EPR controllers. As a result, the number of external components needing to be sourced is far less.

The UHPD solutions from Diodes set themselves apart from the competition, by offering far greater ease of implementation. These solutions are also equipped with advanced smart power management functions (such as smart power-sharing for multiple-charging ports, dynamic thermal power de-rating, LED fault indication, etc.). The intelligence that has been integrated into these solutions is enabled by embedded MCU and built-in firmware through Quick Charge (QC) protocol controllers.

In addition, Diodes has also developed various reference designs that have features to accelerate the development process, along with industry-standard form factors that facilitate production workflows. Also, in response to emerging technology trends, Diodes’ future ACF UHPD solutions will benefit from the performance properties of GaN switches. They will exhibit extremely low standby power characteristics through further integration or the co-packaging of different semiconductor elements into single-chip designs, to increase total UHPD solution competitiveness.

Q. What is the roadmap for your power management product portfolio?

Jin Zhao: The Diodes power management product roadmap highlights innovative development work across a wide range of different product portfolios. It draws on the regular consultations we have with our customer base, as well as a deep understanding of the influence that long-term industry trends are having. Our roadmap includes, but is not limited to, the development of high-efficiency miniature DC/DC converters (combining very small footprint with ultra-low IQ figures) for battery-powered applications where there is only limited space available, as well as more products with AEC-Q100 qualification for next-generation automotive applications (where functional safety considerations need attending to).

About Dr. Jin Zhao

Dr. Jin Zhao was appointed to manage Diodes Incorporated Analog Business Group in November 2020, having previously served as manager of the company’s Linear, Logic, and Power Product Division, within the Analog Business Group. Before joining Diodes back in 2017, Dr. Zhao had held Vice President and General Manager roles at NXP and Fairchild Semiconductor respectively. In these positions, he had been responsible for managing various product lines, including analog interface ICs and high voltage discretes. Before this, Dr. Zhao was employed by Texas Instruments (TI), where he managed the integrated PMIC and over-voltage protection product lines. He also spent a period working at AMD’s fab in Austin, Texas. Dr. Zhao holds a Ph.D. in Chemistry from the State University of New York at Buffalo and an MBA from the University of Texas at Dallas.