I am working on GaN MOSFET Switch for my research work. My operating frequency is 1 MHz. In datasheet, it is given that the required turnoff voltage is -20 V. Here, How can I give -20 V source? which driver circuit is suitable to get -20V and the frequency of 1 MHz?
Hello dear Kodeeswaran Sankarraj
Are you sure about that -20V value?
I think you should check for the threshold voltage (the limit for VGS beyond which the MOSFET can be regarded OFF). Normally they set it to a positive (but not large) voltage, so that for VGS=0 the device is OFF (and for VGS>VTh it is ON. The D-S ON resistance will be smaller as you increase VGS).
Maybe -20V is the minimum VGS voltage that the MOSFET can withstand (when OFF).
Please check again.
On the other hand, for switching frequency issues, you should consider the parasitic capacitances and the turn-on/turn-off delays (must be available in the datasheet).
Best regards...
It is a bit tricky indeed. What typically used in such situations is MOSFET gate driver IC (I guess you need 30V ..40..50V rail-to-rail capable ) like https://ie.rs-online.com/web/p/gate-drivers/6684370 (many more models available beside it)
It is e.g. powered between +10V and -20V rail. You need to deliver logic signal to it, it can be done by optocoupler referenced to -20V . Power of 5V for it might be derived by linear regulator between 10V and -20V. Note the optocoupler may introduce some jitter. For experiments the rails might be delivered by lab supplies.
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