an Alibaba seller comes through, again.

In 2012 Hitachi introduced the RJK6024, a small-die super-junction low-capacitance DPak 600-volt MOSFET, and its datsheet plot showed Crss = 0.65pF at 100V. I badly wanted a bunch for making faster high-voltage amplifiers. But I could never get any in the US, not even a sample. Eventually when I learned that Hitachi Renesas had discontinued the part, I thought perhaps they had never really put it into production.

But recently, working on an improved HV amplifier for LIGO experiments, I decided to make one more attempt to get some. I posted a request for quote on Alibaba, and hey, somebody responded, only 38-cents each. This morning a roll arrived DHL from Hong Kong, and they're fine, not counterfeits. I immediately put one on my HP 4280A C-V mater. Its Crss measured 7.87pF at 10V, 1.76pF at 15V, and 0.78pF at 100 volts. Yes that's 0.1pF higher than the datasheet plot, but then maybe my lead- zeroing efforts were off by 0.1pF. Coss 31pF at 15V, 18.8pF at 30V and 10.5pF at 100V. Yessir, it's real.

--
 Thanks, 
    - Win
Reply to
Winfield Hill
Loading thread data ...

More pedestrian-ly Ali seems to be the only place to get small quantities of alphanumeric LED displays (the kind with the diagonals in addition to 7 segments and decimal point) at a reasonable price

Reply to
bitrex

LIGO?

You've determined it's real from simply measuring its characteristics. Is that really good enough to bet your life on it?

--
This message may be freely reproduced without limit or charge only via  
the Usenet protocol. Reproduction in whole or part through other  
 Click to see the full signature
Reply to
Cursitor Doom

Laser Interferometer Gravitational-Wave Observatory.

Somebody more widely read than Cursitor Doom - like the average five-year-old - would have heard that they have now detected gravitational wave signals from black holes and neutron stars colliding and fusing.

--
Bill Sloman, Sydney
Reply to
bill.sloman

LIGO, Laser Interferometer Gravitational-Wave Observatory. Gravitational waves.

formatting link

Yes. A counterfeit MOSFET couldn't do that. The roll of labelled parts was immediately sent out after my order. No time to prepare a fake-labelled part. Why do that for 38 cents per part? No sir.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

He should've tried asking it directly, you have to shout at them though most semiconductors don't hear too good.

Reply to
bitrex

Did you actually work on the LIGO project ? That would be so CooL !

I used to live not far from the one in Washington state when I worked in Richland, WA.

boB

Reply to
boB

No, I didn't work on anything in the current LIGO observatories, that would have been very cool. But I am working with a group to improve the performance of some optical modulators, etc. This involves increasing the HV amplifier's slew rate, or making a higher bandwidth, or with much more mid-frequency loop gain. Apparently, as well as the LIGOs are doing now, they're working hard to further improve them. I'm creating an advanced version of my AMP-62 design, which some of you know about. I've given away bare AMP-62A boards and am creating a new AMP-62B version.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

Got a link to that? It doesn't google.

Ligo must have the lowest long-term s/n of any science experiment, except the ones with zero results. It took a lot of patience to get the first clear gravity wave.

--
John Larkin         Highland Technology, Inc 

lunatic fringe electronics
 Click to see the full signature
Reply to
John Larkin

Are you looking for an AMP-62 link? Here's one that's about 3 years out of date. I'm upgrading the stuff now.

formatting link

--
 Thanks, 
    - Win
Reply to
Winfield Hill

Stacked current sources! But with LND150s, it works.

--
John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
 Click to see the full signature
Reply to
John Larkin

Yes, but the scheme on the lower left of the diagram works much better, evenly distributes the dissipation. Along with changing to BSS126, and 10x higher critical node pullup current, get dramatically faster slewing.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

Would some newer wide BG devices like GaN or SiC be better for even higher slew rate ? I would think that John Larkin is also using some of that stuff for his pulse generators ?

Reply to
boB

Would some small caps across those two resistors help, reduce Miller effects in the upper fet? Maybe just across one resistor, since Cd-g is already there.

Sometimes adding inductors helps, if you can keep that under control.

You can also completely float the output gate drivers, but that takes more parts.

Bootstrapping is fun too. Sort of the same thing, I guess.

--
John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
 Click to see the full signature
Reply to
John Larkin

Some of the smaller EPC GaN parts are interesting, but only go up to about 200 volts.

I think someone is making 600 volt GaNs now.

I'm using the Cree SiCs, but they are mostly big for this sort of amp.

--
John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
 Click to see the full signature
Reply to
John Larkin

I've been using SiC for my 8ns HV pulser pickers, and I selected the smallest of the parts on offer, which did well driving 50-ohm coax with 6A switching. But sadly they don't offer small parts, so the smallest ordinary MOSFETs have less capacitance than the smallest SiC parts.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

And there were a lot of pre-LIGO experiments.

formatting link

Govert Schilling is Dutch, but he writes excellent English, and his book is a brilliant history.

I've been reading Physics Today on and off for quite a while now, and his book reminded me of quite a few articles that got published there. There were quite a few "resonant bar" gravity wave detectors, and none of them ever detected anything.

Cold fusion research hsn't been going on for anything like as long.

--
Bill Sloman, Sydney
Reply to
bill.sloman

Then they probably picked up your footsteps when you got up in the middle of the night to pee.

Rick C.

Tesla referral code -

formatting link
Get 6 months of free supercharging

Reply to
gnuarm.deletethisbit

That's why LIGO systems are paired. Only the noise that correlates between two LIGO machines that are a long way apart gets looked at.

--
Bill Sloman, Sydney
Reply to
bill.sloman

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.