Class D amplifiers emend the energy efficiency and the size to power ratio of audio amplifiers. Lower gate charge combined with high breakdown voltages and good reverse recovery characteristics bring out high potential for SiC-devices in class D audio amplification. Two prototypes of a PWM-driven class D power stages have been developed. For the half bridge topology, SiC MOSFETs from Cree and superjunction transistors from Infineon (CoolMOS) are used. Comparing the turn-off behaviour, a remarkable lower fall time (1.9x) and improved switching waveforms were investigated for the SiC device. Relating to this, the blanking time for switching the SiC half bridge could be reduced by two. Shorter blanking times significantly emend the audio signal of the amplifier due to less PWM-timing errors and improved THD (Total Harmonic Distortion). The measured fall time matched well with the calculation.
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