AC Switch Application with SIC or GAN FETs

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CHenze
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Is there any special consideration when using a pair of SiC or GaN FETs (compared to regular silicon FETs) in a common source configuration  to create a solid state switch for 90 - 264 Vac Single phase 50/60 applications other then a providing a negative gate drive voltage for the OFF state? 

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Shivam_P
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100 replies posted 250 sign-ins 50 solutions authored

Dear @CHenze ,

For AC switch application, The control of the GaN FETs  is not possible in 3rd quadrant operation. The behaviour is not same as the 1st quadrant and has huge voltage drops during the operation and may lead to higher losses.

Also GaN FETs does not have the inherent body diode. Hence, Common source configuration may not be feasible for your application. However, You can use SiC FETs in common source configuration. But for the mentioned voltage range usually SiFETs are recommended for your application.

Best Regards

Shivam

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Shivam_P
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100 replies posted 250 sign-ins 50 solutions authored

Dear @CHenze ,

For AC switch application, The control of the GaN FETs  is not possible in 3rd quadrant operation. The behaviour is not same as the 1st quadrant and has huge voltage drops during the operation and may lead to higher losses.

Also GaN FETs does not have the inherent body diode. Hence, Common source configuration may not be feasible for your application. However, You can use SiC FETs in common source configuration. But for the mentioned voltage range usually SiFETs are recommended for your application.

Best Regards

Shivam

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Thank You for the reply.  It seems that SiC FETs have an efficiency advantage because the on-state resistance does not increase as much compared to a Si FET with the same resistance at 25C.   

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Shivam_P
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100 replies posted 250 sign-ins 50 solutions authored

Dear @CHenze ,

Considering the efficiency factor for your application if  SiCFET matches your requirement.

You can opt for SiC FET as well apart from SiFET. It is mostly depends on the end application and user choice.

Best Regards

Shivam 

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