Better power transistors. (?)

** But 5V gate IGBTs already exist.

Threshold nominally 1.7V and full conduction(30A) at 4 to 5V.

..... Phil

There's also teeny MSOPs that handle 400V and 300A (pulsed), with similar Vge(on).

Both have embarrassing speed. I don't know if anyone makes those at high voltages either?

Hopefully the article is talking about regular (fast) speed parts, which would be handy indeed.

Also, hopefully they're not just talking about something chintzy, like a nice GaN transistor below a depletion mode regular-IGBT. Which, I mean, that would work, but it won't be as cheap as a proper Si-only part, and won't switch the load any faster, just take less drive.

Or SiC IGBT, or... can they make IGBTs out of GaN? IGHBT? That'd be fancy as hell...

Tim

--
Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Design 
Website: https://www.seventransistorlabs.com/

Assuming you're not limited by source lead inductance. Tom McEwan found that was so much of an issue he got a patent for matching it with an inductive gate kicker - I recall Win Hill trying that and switching 1kv in

this means AM radio will become even more useless due to the interference

m

Perhaps also recently, but I'm referring to these two threads: and

from 19 years ago :)

Clifford Heath.

The recent work was Win's SiC pulser. But I see this predates me; good memory. ;-)

Current link to patent:

The table is excellent, rare that articles on these subjects actually disclose the values used. A bit curious what the layout looked like. The inductors are small, I wonder if a microstrip construction would do.

1N5408s don't exactly have low inductance themselves (maybe 5nH when mounted flush over ground plane?). Much better should be possible today, say with SMC or TO-277 or other low-profile diodes.

SiC schottky also interesting (for the shock line, not so much the final avalanche bit), but basically impossible to find outside of leaded packages, grumble.

Hm, so dynamic avalanche is the same thing that BJTs do, but in a PN junction, and since it's not three-layer punch-through*, it takes extreme conditions to trigger (rapid dV/dt, peak voltage >> Vrrm)?

seems to suggest that's vaguely true: the avalanche mechanism does indeed have a speed limit (despite what the TVS manufacturers will tell you), and exceeding that speed limit makes for interesting physics.

*Or whatever the exact mechanism is, I'm not sure I've seen an analysis of it.

Tim

--
Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Design 
Website: https://www.seventransistorlabs.com/

I think I triggered the discussion, because I was very interested in McEwan's low-tech UWB implementations at the time. My OP doesn't seem to exist in Google's archives.

That's where he uses a common rectifier as an SRD. PIN structure, so why not! But it's not the patent where he generates the 1000V step from a MOSFET. I was referring to this:

The rectifier-as-SRD patent also says this, which I don't find discussed elsewhere: "The present inventor has also built a current-mirror driver circuit (not disclosed in this application) that uses MOSFETs to generate -1 kV,

2 ns voltage steps to drive transmission line 12 with a 1 Watt power supply."

That's a pattern with McEwan. His stud-finder doesn't just give enough for a full schematic, it even mentions preferred chip manufacturers for the common CMOS he used:

They're just bloody big diodes, so they need a big whack.

McEwan and LLNL got mired in an international patent dispute with Time Domain Systems, which prevented us from getting all the nice impulse radar goodies that might have flowed from McEwan's work. I'm sure TDS were legally justified, but I detest them on ethical grounds, because they failed to deliver any earth-shaking technology from it. Now that enough time has passed and the patents are expiring, people here should get busy building all the nice things.

Clifford Heath.

Dunno about that one, but explored my computer, found a SPICE exploration I did Sept 2000, using McEwan's recipe in patent 5,332,298 where he achieved 900V 36A switching in 2ns with a Motorola type 4N100. No datasheet found. I used Motorola's SPICE model for their MTP3N100, and SPICE was indeed able to switch 900V in 2ns, documented in "900V 30kW 2ns with a 3N100". McEwan did amazing stuff.

--
 Thanks, 
    - Win

The second reference is Mikes analysis of McEwans pulse circuit. He references this web page:

But of course the link is broken

Anyone got a copy of it?

Regards

Klaus

I might. I saved three of Mike Monett's html files, dated 19 Sept, 2000. But they don't deal with the 5274271 patent, but instead the 5332298 MOSFET switching patent. Going over Mike's document and my notes, Mike showed that McEwan's patent couldn't work, but my SPICE modeling showed that it could do 900V 2ns high-current falling edges. But just now I noticed that I had used McEwan's 4nH value for source inductance, but datasheet SPICE models say 13nH for a standard TO-247 package.

What's current FCC status on allowing UltraWideband pulsing?

--
 Thanks, 
    - Win

I did my modeling on 23 Sept, but now don't remember doing it, let alone Mike's response after posting it.

--
 Thanks, 
    - Win

Would be interesting if you had a copy :-)

For CISP14, the emission limits are quasi peak and average. So if you keep the average energy low enough, I think you can do whatever pulse you like

I believe the FCC15 has the same measuring definition

Cheers

Klaus