SIC, SIT, V- and JFets

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Dansk

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Joined 2008
#1
I'm getting a little bit confused about all these terms...😕
-and it seems I'm not the only one, since for example Farnell sells these, both as mosfets and jfets:

http://www.genesicsemi.com/images/products_sic/sjt/GA04JT17-247.pdf

Would anyone care to elaborate with regards to the differences between the different types and their advantages compaired to ordinary mosfets, in such a simplistic way, that the tecnically chellenged members inhere (Me) would be able to understand it...?

Best Regards
 
#2
There was a discussion earlier about that genesicsemi. I belive the description is intended to make you believe it's a high power jfet but it's some combination of a regular transistor and a fet. Not recomended. In general SIT devices just have a lot less distortion than mosfets. Nelson has a article you may want to read,

FIRST WATT SIT INTRO
 
#4
SiC is a material type (Silicon Carbide). MOSFETs, JFETs, and SITs, could all be made in SiC.

SITs and VFETs are the same thing, tho VFETs could possibly be viewed as a subset of SITs. Both are types of JFETs, but they have a burried gate, which is similar to a vacuum tube's grid, giving them triode-like saturation characteristics
 
#11
Great, great, great!!!

Hi Mike, I wasn't able to be around to watch it live, but have just seen it now. I think it was very informative - and a great idea to build something live. I don't have any preferences with regards to what you should build, but I am very sure, that it'll be possible to pick up a lot of tips and tricks while following your building of things. I for one will be keeping an eye on what you're doing!🙂

- By the way, I think it is very nice, that you allow yourself to go through things with such patience and relatively low speed.:magnify:
 
#13
Michael Rothacher said:
SiC is a material type (Silicon Carbide). MOSFETs, JFETs, and SITs, could all be made in SiC.

SITs and VFETs are the same thing, tho VFETs could possibly be viewed as a subset of SITs. Both are types of JFETs, but they have a burried gate, which is similar to a vacuum tube's grid, giving them triode-like saturation characteristics
Click to expand...

Would that burried gate be something like what is described in this 1974 patent?

FIELD EFFECT SEMICONDUCTOR DEVICE HAVING AN UNSATURATED TRIODE VACUUM TUBE CHARACTERISTI
 
#15
C2M0280120D $5.43 vs GA03JT12-247 $9.24
Digikey qty1 at time of this posting...

These are both 1200V, similar in gate capacitance
with Cree being slightly less. Also similar Coss, with
Genesic being slightly less.

Cree's offering conducts twice as much current,
has 5 times less Miller capacitance, and costs
half as much. Capacitance is linear above 25Vds,
yet balloons like mad below that voltage.

Genesic's stores only half as many Joules in Eoss.
In hard switching, that could be a big advantage.
Lacks a body diode, which could be good or bad.
Capacitance only becomes linear above 100Vds.
Below that knee is much rounder gentler balloon
you may be able to live with. But unfortunately,
it is also entirely Miller, you'll have to drive it,
and drive DC into the gate as well...

-----

Mind you, the worst ballooning capacitance of all
I have ever survey'd would be Infineon C7 series
Silicon Superjunction. Neither of the above SIC
are into that category of non-linear capacitance.

If Cree's low voltage capacitance was mad, then C7
gets full Gingham knee-sock bizarre below 40Vds.
Not that such a feature is all bad news. It can be
very useful to achieve soft switching for both edges.

You won't enjoy low Vds for linear audio purposes.
How much rail V are you willing to throw away to
play keep away from the capacitance monster???
Volts standing about unused, increase dissipation.
 
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