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GaN's datasheets missing td(on)/td(off)/tr/tf
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T3sl4co1l:
What are you really doing?  There is no meaningful equivalent of a higher-voltage "IRF510" "switching" at 20MHz (which implies switching speeds of a few ns at most).

GaN can do that, but it's in no way equivalent, and as indicated, is no beginner's project!

Tim
ejeffrey:

--- Quote from: Free_WiFi on February 03, 2020, 05:21:46 pm ---Ok guys,thank you,but can you be more clear?
I'm a beginner and I do not understand yet about how to calculate td(on)/td(off)/tr/tf by only having the Qg.


P.S can you advice me some good book about transistors & semiconductors in general?
Thanks

--- End quote ---

Basically, FETs respond to electric field in the channel essentially instantaneously (at least compared to normal switching times).  The turn-on time is mostly dictated by how fast you can stuff Qg into the gate.  Rise/fall times are basically measurements of how much current you are driving into the gate.
Miyuki:

--- Quote from: ejeffrey on February 05, 2020, 09:45:46 pm ---
--- Quote from: Free_WiFi on February 03, 2020, 05:21:46 pm ---Ok guys,thank you,but can you be more clear?
I'm a beginner and I do not understand yet about how to calculate td(on)/td(off)/tr/tf by only having the Qg.


P.S can you advice me some good book about transistors & semiconductors in general?
Thanks

--- End quote ---

Basically, FETs respond to electric field in the channel essentially instantaneously (at least compared to normal switching times).  The turn-on time is mostly dictated by how fast you can stuff Qg into the gate.  Rise/fall times are basically measurements of how much current you are driving into the gate.

--- End quote ---

And if you want to use some tool for calculation try for example
TI power stage designer tool

it have FET Losses calculator, what can from transistor parameters and drive voltage calculate switching times and losses
I use it for quick check when choosing switching transistors
Free_WiFi:

--- Quote from: T3sl4co1l on February 05, 2020, 08:58:37 pm ---What are you really doing?

--- End quote ---
My diy projects are based on RF stuff and coil induction heaters like this :

So for this reason i'm searching an better alternative to IRF 510 with higher VDS and super low capacitance.
Free_WiFi:

--- Quote from: blueskull on February 06, 2020, 04:19:20 pm ---If no modulation is needed, why not using class E with an ordinary silicon or SiC FET?
You don't need super low Cds, nor super low Cgs (providing Rg is low).
Basically any device with a good gate runner design and no intentional internal Rg will work fine.

--- End quote ---

Thanks you  :-+

So... i'm reading some book's (some are from soviet union and some are from united states) from 60's,70's and 80's and there's plenty of fun projects like :
Plasma generator on mosfets;
Radio amplifiers on mosfets;
Portable desktop - super pocket welding power supply for precision welding + diy probe for the electrode;
Analog arbitrary waveform generators on mosfet;
Linear RF amplifier on mosfet;
Precision Pocket Induction heaters for plugs welding/soldering like here :


And so on... so basically as i'm interested in all of these stuff,for this reason i'm searching an nor super cheap nor super expensive Mosfet which must be at least a little better on Vds and parassitic capacitance :)


P.S : I forgot to tell you,IRF 510 is not very good for the DIY of Metcal power supply,because of the low Vds wich is making it pretty vulnerable in that kind of system  :horse: 

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