Selecting a power transistor has become less about identifying a universally superior technology and more about matching device behavior to the demands of the application. Silicon MOSFETs, IGBTs, SiC MOSFETs, and GaN HEMTs each offer meaningful advantages, but those advantages do not carry the same value across every converter, motor drive, or power stage. The decisive factors are the electrical and thermal realities of the design: bus voltage, current profile, switching frequency, allowable temperature rise, control strategy, commutation behavior, PCB parasitics, and system cost targets.

The discussion begins with the switching and conduction mechanisms that shape the behavior of every power transistor, including crossover loss, inductive switching, parasitic capacitance, reverse conduction and charge-recovery behavior, and the practical distinction between hard-switched and soft-switched operation. These operating modes create different selection priorities: hard-switched stages are often strongly influenced by turn-on loss and commutation behavior, while soft-switched stages depend on the charge to be commutated, the available current, and the ability to maintain soft switching across the operating range. On that basis, it compares silicon MOSFETs, IGBTs, SiC MOSFETs, and GaN HEMTs in terms that matter to designers working on real hardware: voltage range, current capability, switching performance, gate-drive implications, thermal behavior, and implementation sensitivity.

The discussion then moves into application context, including PFC, resonant conversion, synchronous rectification, and motor-drive design decisions, where lower device loss alone does not guarantee the best overall result. Thermal margins, board design, control choices, and total system cost all influence whether a given device technology improves the converter in a meaningful way.

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