I suppose some of us audiophools should get specific about what we'ld like to see in the future papers authored by fellow member Mike M, but, it"s a big complicated subject. Putting all this down in clear consise... wait a minute I'm not workin! Speaking of work. What do you know about GaN? their not letin me play with it but, everybody including customers thinks it hopeless after years of marketing bla anyway... like some of the other SiC players I suppose...
Back to the subject at hand...I'd like lower exponectial C increase and at a lower Vds! what's the deal, these things look worse than MOSFETs in that regard??? As long as we're here these things have the C and leakage also
I'd like to see the Vds vs. Ids transfer curves from the data sheet below the Ids of the data sheet (lower than Vgs1.5V for R100 and greater than -2V Vgs for R085), like 1-5A and at least up to 6-8Vds.
I'd like too see a SOA graph, transconductance vs. Ids(@0-5A) graph and real Typ Rthj numbers??? The Tc of the Vgs sounds Negative but excelent from what I've seen, read, heard???
I'm just dumpin whats in my head so I can think up more stuff but, these are all important factors to have in one of our output parts. Since we're not swicthing 100s of Volts with inductors and Cs that stuff dosen't make the datasheet???
I know I missed a bunch of important stuff, maybe someone will pick it up? I've had all kinds of electronic expeirience from Moto OpAmp device guy in the 80's to ASICs. Wafer Processing, Test (Mostly) and Assembly. SMPs server Apps now. But, it don't matter. If your into audio, you aren't learning this stuff in school or work and most of the PhDs I work with, can't even understand what I'm taling about??? and won't bother, and, they think I'm some nut? But I never saw my CTO do anything but take the money they could be paying me? One of these days I think I'll challenge our classD group to a contest of Class A to Our class D. Probably best done after I have another job...
Wow, that's a lot to digest. I'll limit my comments to a couple of thoughts cause I gotta work too.
- "everybody including customers thinks it hopeless after years of marketing bla anyway"
- "I'd like to see the Vds vs. Ids transfer curves from the data sheet below the Ids of the data sheet (lower than Vgs1.5V for R100 and greater than -2V Vgs for R085), like 1-5A and at least up to 6-8Vds."
My next article will be looking at this aspect of the R100 in experimental and modeling detail. The issue of transconductance vs. Id will be touched tangentially (ha ha, literally!).The company has one of the most vertically complete SiC fabs outside of Cree. (Notice I use the word "has" because it is still there across the street from where I write this.) After raw wafers were received, only implantation was outsourced. Back end outsourcing began with packaging (meaning sawing was done in house), but with commodity packaging like TO247, this is common.
Dr. Mazzola and flg. Future power JFETs for the audio diy community may have a better chance competing with and be priced like IRFP240. This old faithful MOSFET is very much admired and used [liberally?] by the students of Mr. Pass. DIYers may ask: Do we need the 1200 V rating of the CREE MOSFET device? This impressive spec may have intentions to compete with 600 V IGBTs and 1200 V SiC JFETs in power conversion end uses. Is there evidence that the 1200 V rating impacts the coveted sonic attributes of R100A?
Best regards
Best regards
frew thoughts/q's from Mighty ZM :
- sort of humorous - if I'm going to ask SSFan - where we can expect new SJEP and SJDP , in quantities ...... whatever you are going to name them ..... I'm expecting that your answer will be of much greater verity than answers from Linear Systems guys,claiming that their small sig pfets are right around the corner
-while we are at it - is there any need in pro field for small - I mean really small - SIC ?
these will be fine as triodish thingie ; gimme something in range of EC8010 , EC8020 ........ or even 7788 (I'm going to Shade it , then )
life is fun , for Greedy Boyz , in Papaland
- sort of humorous - if I'm going to ask SSFan - where we can expect new SJEP and SJDP , in quantities ...... whatever you are going to name them ..... I'm expecting that your answer will be of much greater verity than answers from Linear Systems guys,claiming that their small sig pfets are right around the corner
-while we are at it - is there any need in pro field for small - I mean really small - SIC ?
these will be fine as triodish thingie ; gimme something in range of EC8010 , EC8020 ........ or even 7788 (I'm going to Shade it , then )
life is fun , for Greedy Boyz , in Papaland
frew thoughts/q's from Mighty ZM :
- sort of humorous - if I'm going to ask SSFan - where we can expect new SJEP and SJDP , in quantities ...... whatever you are going to name them ..... I'm expecting that your answer will be of much greater verity than answers from Linear Systems guys,claiming that their small sig pfets are right around the corner
-while we are at it - is there any need in pro field for small - I mean really small - SIC ?
these will be fine as triodish thingie ; gimme something in range of EC8010 , EC8020 ........ or even 7788 (I'm going to Shade it , then )
life is fun , for Greedy Boyz , in Papaland
- Well, I think we can agree that we don't need a 1200 V part. No need for me to make that into a rhetorical question.
- You do want the "soft" saturation (or even SIT like) output curves of the R100, but that is not a unique feature of SiC, but instead a consequence of the design of the channel. That could certainly be built into a silicon part if there was a market to justify it. After all, SIT's were first built in silicon and some MOSFETs deliver at least some of the soft saturation that can be used to balance the square law non-linearity. The problem is that in power switching, soft saturation transitions are considered less than ideal, hence there is a market force working against the DIY'ers interests.
- Can we deliver a SiC part at the price of a IRFP240? No. (I didn't even bother with "not yet.")
- Do we need a part made of SiC? Depends. At first, I thought the answer was definitely "no." But I have had second thoughts. You see, you all insist on going Class A and that means you want a little eny weeny tiny part to dissipate tens of Watts. Why do you want it to be eny weeny tiny? Cause you hate input and Miller capacitance! That means you all are at least partially in the market for power density. That is the value proposition for SiC, and it comes out dollars and cents ahead of silicon as we increase the voltage. That's why you've been stuck with 1200 V when you don't need it. But SiC also has one other crucial feature that enables power density. The thermal conductivity of SiC is about three times greater than silicon. In contrast, gallium arsenide is one half that of silicon. No semiconductor with a greater band gap than silicon can actually deliver higher power density in a practical application if it sacrifices thermal conductivity. Yikes!
Here's a thought. Diamond (cubic carbon) has the highest band gap of the practical semiconductors and even higher thermal conductivity than SiC! Cost?
Here's a thought. Diamond (cubic carbon) has the highest band gap of the practical semiconductors and even higher thermal conductivity than SiC! Cost?
Carbon is just above silicon on the perodic table. What is the band gap voltage?
I would like to see a depletion mode device with Gm 1 mho, Vgs(off) 2V, Idss 2A. Or a device that could be paralleled to be equivalent.
Attachments
......Cost?
OK - what I meant - I don't mind capacitance and highish voltage ; give us ( chasing primarily big guys energy related market ) what you already had (SS SJEP and SJDP) , and we are (more than ) good
dreaming - give us ( chasing again big guys market , hopefully ) small power SIC , (hopefully ?) with triodish transfer function ...... so we'll have those small ones to drive those big ones , and spare a little gain for little NFB , local or overall
thinking about 2SK77B ( as biggie ) and 2SK78B & 2SJ78B (as eenieweenies) , used by guys at Š”Ž®‰ïŽÐ ƒfƒWƒ^ƒ‹ƒhƒ�ƒCƒ“
Got RO85SJDP in this very configuration. I like ZM idea of small signal version.
GB time
Now that you've been around a bit Mike:
"Do we need a part made of SiC? Depends. At first, I thought the answer was definitely "no." But I have had second thoughts. You see, you all insist on going Class A and that means you want a little eny weeny tiny part to dissipate tens of Watts. Why do you want it to be eny weeny tiny? Cause you hate input and Miller capacitance! That means you all are at least partially in the market for power density. That is the value proposition for SiC, and it comes out dollars and cents ahead of silicon as we increase the voltage. That's why you've been stuck with 1200 V when you don't need it. But SiC also has one other crucial feature that enables power density. The thermal conductivity of SiC is about three times greater than silicon. In contrast, gallium arsenide is one half that of silicon. No semiconductor with a greater band gap than silicon can actually deliver higher power density in a practical application if it sacrifices thermal conductivity. Yikes!"
Now that you've been around a littlte, I need to munch on these morsels for a while myself, HHmmmm...
"Do we need a part made of SiC? Depends. At first, I thought the answer was definitely "no." But I have had second thoughts. You see, you all insist on going Class A and that means you want a little eny weeny tiny part to dissipate tens of Watts. Why do you want it to be eny weeny tiny? Cause you hate input and Miller capacitance! That means you all are at least partially in the market for power density. That is the value proposition for SiC, and it comes out dollars and cents ahead of silicon as we increase the voltage. That's why you've been stuck with 1200 V when you don't need it. But SiC also has one other crucial feature that enables power density. The thermal conductivity of SiC is about three times greater than silicon. In contrast, gallium arsenide is one half that of silicon. No semiconductor with a greater band gap than silicon can actually deliver higher power density in a practical application if it sacrifices thermal conductivity. Yikes!"
Now that you've been around a littlte, I need to munch on these morsels for a while myself, HHmmmm...
Well, ZM, why didn't you say so? Actually, you did. My apology for misunderstanding what you were asking about. It just so happens that the company made small parts for the kind of small signal applications you have in mind. Where is my head? I should have thought of that myself!
They were originally created as a special order for a customer that wanted the high temperature capability of the SiC JFET, not the high power density / high voltage capability. The customer liked them a lot. I'll have to look into whether any of those are still around...
Mike: "I had beers with my business partner this evening talking about all of this. It is definitely more interesting that some other stuff I have to do to earn a living."
Hey bud, Next time your close R.I. there is nothin like a few brews to create somin new! How 'bout Rock Bottom in Boston, Havent been to one in 5-6 years. Since I left Phx... I'm open...
Ruogh!
Hey bud, Next time your close R.I. there is nothin like a few brews to create somin new! How 'bout Rock Bottom in Boston, Havent been to one in 5-6 years. Since I left Phx... I'm open...
Ruogh!Mike: "I had beers with my business partner this evening talking about all of this. It is definitely more interesting that some other stuff I have to do to earn a living."
Hey bud, Next time your close R.I. there is nothin like a few brews to create somin new! How 'bout Rock Bottom in Boston, Havent been to one in 5-6 years. Since I left Phx... I'm open...
Hey, you might be surprised when I take you up. I have business in Boston from time to time.
Small parts? We don't need to cloud your mind but, The 550 part I've been thinking would be cool in a X1000 style circuit. A Pass Classic! High current (50-100mA) diff pr. of 550s in folded cascode driving the output stage. 2 stages with the Pass supersymetry! But, I wouldn't ask you to cloud your mind with the http://www.diyaudio.com/forums/pass-labs/99-x100-backengineered-here.html thread
O.K. 1 other thing What's the deal with Pd or shoud I say MaxTj? Everybody seems to be thinking with these SiC devises that it is the TO-247 plastic pkg is the device Temp limit not the so called 300 Degree Sic Die limit??? Before my foot is in the way of my mouth, can you comment on that? Say for instance I want to run my amp for a MTBF or whatever of 20 years? What's the recomended max Tj?
This is also one of those times when I wonder what is on N.P.'s mind? Reading all this and every few minutes a MMMuuuhhhahahaha, and Jill in the background asking, "what's that sweety?"
Hey, that's what happens at my house
What's the deal with Pd or shoud I say MaxTj? Everybody seems to be thinking with these SiC devises that it is the TO-247 plastic pkg is the device Temp limit not the so called 300 Degree Sic Die limit??? Before my foot is in the way of my mouth, can you comment on that? Say for instance I want to run my amp for a MTBF or whatever of 20 years? What's the recomended max Tj? This is also one of those times when I wonder what is on N.P.'s mind? Reading all this and every few minutes a MMMuuuhhhahahaha, and Jill in the background asking, "what's that sweety?"
Hey, that's what happens at my house
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O.K. 1 other thing
This is also one of those times when I wonder what is on N.P.'s mind? Reading all this and every few minutes a MMMuuuhhhahahaha, and Jill in the background asking, "what's that sweety?"
Hey, that's what happens at my house
175 C Tj(max) with plastic parts. There is still some doubt in my mind that we know the parts will last "20 years" at elevated temperatures. The SiC is not the issue. A SemiSouth JFET contains other stuff too, like nickel silicide ohmic contacts, aluminum final metal and wire bonds, oxide for trench fill and passivation, etc. I once managed a research project with NASA in which the parts "survived" at more than 400 C, but this was over a matter of days or weeks and the die were made with gold metal and interred in special packaging by the Jet Propulsion Laboratory. The parts were being evaluated for a one way trip to Venus. MMMuuuhhhahahaha!
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