Q&A - Why did Apex decide to integrate SiC vs GaN in their new PWM amplifiers?

December 1, 2020

Q?

Why did Apex decide to integrate SiC vs GaN in their new PWM amplifiers?

A !

Both silicon carbide (SiC) and gallium nitride (GaN) have similarly high wide bandgap energy, giving them an edge in switching capabilities, efficiency, high power and high voltage handling over other semiconductors, such as silicon, germanium, or gallium arsenide.

But why did Apex use SiC over GaN?
Despite having similar bandgap energy, SiC and GaN differ in their breakdown voltage and switching speeds. GaN is more suitable for high-frequency applications, while SiC devices have a higher breakdown voltage. Another key difference between SiC and GaN is their thermal conductivity. Silicon carbide's thermal conductivity is much higher than that of GaN, giving it an advantage in applications that involve higher temperature or power. 

Additionally, the RDS(ON) of SiC carries a significantly lower temperature dependency compared to that of GaN; temperature rise of the junction temperature from room temperature to 125°C will more than double the on-resistance of a GaN device, while it causes only around a 25% increase for a typical SiC MOSFET. This is an important characteristic of SiC devices used by Apex as we continue to expand our portfolio of products designed to support high-temperature applications where temperatures may reach 150°C or higher.

These features make SiC MOSFETs better suited than GaN for application in Apex's PWM amplifiers which are designed for operation in harsh environments and target voltages of 650 V or higher. To realize the maximum benefit from SiC, Apex integrates these MOSFETs into hybrid packaging such as their SA310 and SA110, together with complementary gate control.

For more information on Silicon Carbide and the Apex products that use it, watch the webinar, or read about Apex's contribution to the SiC/GaN debate in Power Electronics.