Exploring the Integration of MOSFETs in Modern Power-Switching Architectures
In the world of power electronics, two main types of transistors dominate: MOSFET switches and bipolar junction transistors (BJTs). MOSFETs, with their rapid turn-on/turn-off capability and low on-resistance, are particularly useful for power switching circuits. On the other hand, BJTs respond to current changes at their inputs and are suitable for driving relatively slow-changing inductive loads.
However, a new contender is making waves in the power transistor arena: Gallium Nitride (GaN) transistors. These transistors significantly outperform traditional silicon MOSFETs in terms of power-supply efficiency and form factor improvements.
GaN transistors boast higher electron mobility, wider bandgap, and better thermal conductivity. These properties enable faster switching speeds, reduced conduction and switching losses, and operation at high frequencies, reducing the size and cost of passive components in power supply designs. This results in smaller, more compact, and more efficient power conversion systems.
Specifically, GaN transistors can achieve up to 30% lower power losses compared to equivalent SiC MOSFETs, smaller die sizes (14% smaller), lower on-resistance and reduced switching losses, the use of compact, multilayer ceramic capacitors, and improved thermal management and reliability.
In contrast, traditional silicon MOSFETs excel in many conventional power applications but are limited by slower switching speeds and higher losses relative to GaN devices. MOSFETs typically dominate high-frequency applications due to their switching performance and efficiency.
Different transistor types have their own strengths and typical applications. MOSFETs are widely used in power supplies, motor drives, MPPT controllers, load switches, inverters, and industrial automation, often favoured for high-frequency switching and efficiency in compact designs. Bipolar transistors (BJTs) are generally used where high current and voltage applications are required but are less common in modern power electronics due to their slower switching speeds and higher drive requirements. Insulated Gate Bipolar Transistors (IGBTs) combine the efficiency of MOSFETs and the voltage/current handling of bipolar transistors, making them ideal for high-voltage, high-power applications such as electric vehicle drives, industrial motor controllers, and power inverters.
In summary, GaN transistors represent a modern, efficient alternative to MOSFETs, especially when form factor and efficiency are critical. MOSFETs, bipolar transistors, and IGBTs remain important across a broad spectrum of power electronics applications depending on voltage, current, frequency, and efficiency requirements.
Switching-power-supply designers should pay attention to the safe operating areas (SOAs) specified in the transistors they intend to use. It's also worth noting that Insulated-gate bipolar transistors (IGBTs) are a third type of transistor that enable faster turn-on/turn-off behavior for bipolar devices, though not as fast as MOSFETs.
As the power electronics industry continues to evolve, the over-specification of power transistors may eventually be prevented by an ongoing smoothing, filtering, regulation, and pre-regulation of the entire power-transmission chain.
[1] GaN Transistors: The Future of Power Electronics [2] Power Semiconductor Devices: Fundamentals, Devices, and Applications [3] Gallium Nitride-Based Power Devices: Fundamentals, Devices, and Applications [4] Multilayer Ceramic Capacitors: Fundamentals, Applications, and the Future [5] Thermal Management of Power Electronics Devices and Systems
- The innovative GaN transistors, showcased as the future of power electronics, significantly outperform traditional silicon MOSFETs in terms of power-supply efficiency and form factor improvements.
- In the power transistor arena, GaN transistors are becoming increasingly relevant due to their higher electron mobility, wider bandgap, and better thermal conductivity, which enable faster switching speeds and reduced power losses.
