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Gate Coupling (x-post)




 
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Author Topic: Gate Coupling (x-post)  (Read 221 times)
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g7klj
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« on: June 01, 2018, 02:55:26 AM »

Cross-posted from Class E as I fear I put it in the wrong section of the forum:

Hello, dear fellow AM'ers!

Don't you hate it when you slip with the probe, or otherwise "get creative" with your lovely Class E output stage, causing just one FET to go short from Drain to Gate.

As you know , this will also deposit "HT" on the driver.

So there's pain pain pain because now not only do you have to change the FET, you also have to replace the driver IC (which can cost more than the FET).

I had a good old read of the forum yesterday and somebody somewhere said "isolate the gates from each other".

So, any non-obvious issues with AC coupling from the output of the driver to the gate(s), say 0.1uF 100V, and a diode to deck on the FET side of the capacitor, a la DC restorer?
Anode of fast diode to deck.

The DC restorer feeds the driver through a 39-Ohm resistor.

Now when some FET deposits 50V on the gate when it dies, damage should be limited to just that FET (if you are lucky), right?

Just thinking aloud but at first blush I can't see why that is not an improvement on all the DC coupling typical of Class E RF strips.

Feedback welcome.

Regards

Steve
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