GaN - The Next Big Thing

In 1906 Lee De Forest and Robert von Lieben invented the first vacuum tube triode. Initially it was used to amplify telephone and radio signals. But the use of this transistor precursor was not widespread until Bell Laboratories developed the first working transistor in 1947 based on Germanium. Then, in 1954 we saw the first silicon transistor invented by Morris Tanenbaum and Calvin Fuller from Bell Laboratories. Much later, in 1959 Atalla Mohamed and Kahng Dawon invented the MOSFET, making it possible to build high-density integrated circuits (ICs), the precursors of our current integrated circuits.

Left to Right: First Vacuum Tube Triode / First Germanium Transistor

Silicon transistors continued to evolve through the years and eventually split between different applications: memory, microcontrollers, power supply. Each of these fields has its own unique challenges.

Let’s look at the power systems, for example. For years, power design engineers mostly worked with linear regulators. In 1970 low loss ferrites became available and demonstrated switched mode power supply superiority. At that time, 20 kHz was considered high frequency and was highly appreciated because it was inaudible. The early 80’s saw an explosion of silicon startups raising switched mode power supplies frequency to the 100 KHz-1MHz range, and thus considerably reducing the size of the power supply. Beyond this point, the proliferation of personal electronic devices (computers, cell phones, home electronics, IoT, laptops, tablets) has driven the demand for smaller and more efficient power supplies.

Between 2000 and 2010 the industry relied on silicon (Si) to improve power supplies. However, we have reached the limits of Silicon properties - there is not much more that can be improved in terms of packaging and manufacturing. We need new materials to keep improving the designs and meet modern power supply density and efficiency expectations.

Fortunately, it seems like Gallium Nitride (GaN) is one of those new materials that will help us reach this goal. This material has been around since the 1990’s in LEDs. Its wide band gap and multiple alloys makes new applications like daylight LEDs, accurate color rendering, and LED screens possible. So how can this be of any use in switched mode power supplies?

Gallium Nitride Benefits

Bellow table shows a comparison between Silicon and Gallium Nitride. Not only is the RDSon smaller, but the overall parasitic capacitance is reduced. These properties bring two main advantages over Si:

- Higher efficiency and cooler temperatures under full load

- Higher switching frequency, which implies smaller power supply.

Figure 2: MOSFET vs GaN, Texas Instruments, Introduction of GaN technology

Designers exploit one or the other advantage depending on the application being designed. In a cell phone or laptop, the DC/DC converter will take the full advantage of the cooler temperatures as no one likes to hold a scorching cell phone. They will also take advantage of the high frequency capability to shrink the design, therefore reducing the device’s size or allowing it to carry more functions. Maybe the most noticeable benefit is the increased battery life because of the more efficient power conversion.

Many other industries could benefit from high switching frequencies. LiDAR systems use pulse lasers to create a three dimensional image or map of the surrounding area. Applications include geological surveys and meteorology for natural resources exploration, and most recently, automotive.

As shown below, using GaN in LiDAR devices allows higher resolution mapping. Acquiring and processing environments at a high resolution is one of the key for autonomous driving decision processes, as we need to eliminate misinterpretation.

Figure 3: Laser driver, silicon vs GaN; Efficient Power Conversion Lidar solutions

Würth Elektronik and New Semiconductors

In 2015 global internet and electronic use emitted as much CO2 as the aviation industry, their CO2 emissions have doubled every year. Many areas are being improved to attenuate the impact on our planet and power designs is one of them.

High power applications have also reached the limits of standard Silicon. To keep improving their designs, engineers have started to develop Silicon Carbide (SiC) semiconductors. Just like Gallium Nitride, SiC allows higher frequencies and smaller designs. The graph below shows the ideal material depending on the power and frequency you are planning to use. Smaller devices tend to be more efficient and cheaper, which explains why the industry is developing materials that can switch faster.

Figure 4: Si vs Si SJ vs IGBT/GTO vs SiC vs GaN, Texas Instruments Introduction of GaN technology

Würth Elektronik is the leading European manufacturer of electronic and electromagnetic components. Our large product portfolio already covers the new requirements brought on by new semiconductor materials. We constantly innovate to adapt our package size to tomorrow’s applications. We foresee GaN and SiC to become the dominant materials in power electronics, which is why for the development of our next product generation we are working in close collaboration with IC manufacturers - particularly with GaN pioneers such as Texas Instruments, Efficient Power Conversion and Navitas Semiconductors. Together with our partners, we aim to offer the best products and solid proven solutions to our customers – Click here to browse our reference design selection.

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