Nanoamp calibrator again

May 31, 2012 49 Replies

Here's the trick how to do that: Place the standard symbol for NPN, shift-rightclick into it, change the prefix to X and the value to BFP640FESD, then copy the subcircuit into the SPICE file via the command text box. That's it. Just tried that with Q4 in your circuit -> woiks.

Basically the old Ayton-Perry trick but only half turn. Not sure if you have HoJo's book but if not, this works as illustration what you'd have without any tricks:

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Take the 0402 side case but place the vias in the pads. Should get you under 0.2nH. Now place two of those, super-close to each other, run the signal trace down the middle of them (sideways), connect one on the left and one on the right. GND would then be vice versa, first right, then left. Now the loops are opposing and so are the parasitic magnetic fields, helping the cancel each other. Well, to some extent.

There are also caps with four pads but not sure how low they'll get you down in inductance.

You can also get 01005 size caps from Murata and if still not good enough parallel a few, then the parasitic inductance is miniscule. But you'll probably need lasered vias in order to have them in-pad, I don't think those can be drilled.

Have the ground plane right underneath and use a very thin board so the via lengths are small. Because they niow become a significant contributor to the parasitic inductance.

With stuff like this you either have to sit next to the layouter or do the layout yourself.

Back to the darn irrigation valve now, but this time I'll first test it in the driveway. If you hear *POP* from out west then the contraption I made to pressurize it has burst.

Regards, Joerg http://www.analogconsultants.com/

You don't have to, it's much easier than that. See my other post from a few minutes ago.

Regards, Joerg http://www.analogconsultants.com/

PS: Right-click is enough, no need to press the shift key. I was just used to that from another program

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Regards, Joerg http://www.analogconsultants.com/

It's all about the / issues for the most part.

most of the time, that can be fixed, copy and paste in note pad, and set the line returns. Move that into spice afterwards.

These browsers don't lend themselves to generating plan ASCII text very well, especially of you are moving from uni-code text.

But then again, it could be some other problem with just incompatible scripts.

jamie..

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I had no problems. You have to copy the *.sub file into the sub folder and the *.lib file into the lib folder.

George H.

Yes, I did that and then it worked. All you have to do is copy it into the same directory where the *.asc file is. That's why I posted the method to have it all inside the *.asc file, makes it much easier for others to download and simulate.

Regards, Joerg http://www.analogconsultants.com/

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I used Firefox to look at your website, and cut and pasted from there into Notepad, which is the most innocuous of the Microsoft editors. I use Notepad to open my own .asc files, and cut and paste from Notepad into Firefox to transfer LTSpice .asc files into my postings here, and that seems to work.

-- Bill Sloman, Nijmegen

Am 02.06.2012 23:03, schrieb Joerg:

I find those x2y capacitors quite convincing.

(and 400 others)

They lead to a via placement that cancels some of the inductance. I have bought samples, but had no time to really test them.

Gerhard

Yeah, Phil needs to buy a bunch of this stuff and also get used to the

01005 SMT size if he has more such design jobs coming. You can't even see those anymore. And absolutely positively no sneezing on the job :-)
Regards, Joerg http://www.analogconsultants.com/

You can't even breath with those.

tm

Am 03.06.2012 16:51, schrieb Joerg:

I once showed the Murata 01005 capacitor kit to a customer's solder ladies. They were not amused :-)

Gerhard

I highly doubt we'll ever use them. The MEs are balking at a few 0201 decoupling capacitors (needed for fine-pitched BGAs). Everything (that can be) is 0402s. That's more than enough for my eyes (and dexterity), even with a Mantis.

That's basically what I did, except I used gedit, rather than Notepad.

"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

Maybe just right click and download it directly.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net

And exactly that is one of the sad, sad problems we have in the western world. "Oh, that's too difficult!". In Asia they usually say "Ok, let's see if we can get that done". If we don't push the envelope, someone else will. Followed by jobs going away.

That's ok, same here. But production folks need to get their hands around that. Else their jobs will go away some day. At my previous employer our MEs encountered the same attitude at the major semiconductor equipment makers that your MEs professed: "You cannot do flip-chip bonding to 5um precision". So we built it ourselves together with a contract manufacturer where they didn't wet their pants when looking at those specs. Not just one but untimately three machines. Old saying: Man who says it cannot be done shall not stand in the way of man doing it.

Regards, Joerg http://www.analogconsultants.com/

Not too difficult. Not reliable enough, or at least not proven so.

OTHO, just because it can be done, doesn't mean it should be done. ;-)

I already had one, but called it subckt_NPN, so, rather than rename that, I used yours instead.

I've got subcircuit FETs, too.

"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

Ooh - I like that!

"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

THen you were not listening to the man that said "It will not" be done :)

I've had to deal with a prior engineer that filed a failure report on a project and stated that it was a fail concept, not a failure their part, just a bad concept that can not work.

It's funny, because one of these concepts that I know of, got put in operation, working of course, and he got very testicle about it.

It's amazing how one person can hold back advancement, just because they refuse to get others in involved that may have the answer to their quest. You know, that face saving thing?

In the old days, people would disappear if you crossed the line of the old mighty! Now days, they are found dead by an apparent suicide they could of no way done themselves.

Jamie

I have seen boards with lots of 0201 on there where the solder job was of excellent quality. From Asia. I don't think they'll have an issue with 01005.

True, but if it provides an upside for the end customer then it has to be done. One of our competitors found out the hard way and a few years into it they threw in the towel, essentially ditching their whole intravascular ultrasound business. This was HP Medical, no less.

Regards, Joerg http://www.analogconsultants.com/

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