another board

ftp://jjlarkin.lmi.net/Board39.jpg

This is an 8-layer mixed-signal thing. On the left is a PCIe interface to a Kontron mini-ITX sbc.

Upper-right is a cluster of five spread-spectrum switching regulators, all inductor isolated from everything coming and going. I may slice some ground planes around there just to terrify Joerg.

The brown pour is where the pipeline ADC is, differential fed from the two SMB connectors to its right.

This also has a couple of 128 Ms/s arbs and tons of various digital i/o things and some DDR2 dram to feed the arbs, and a programmable microengine to fire shots. The FPGA is a Spartan 6/45, which we actually have now.

The Brat did the layout; not bad for a psychology/softball/beer pong major.

John

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John Larkin
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Which CAD program did he use ??

don

Reply to
don

She. Boys don't play softball in college. It's PADS, version 5.

John

Reply to
John Larkin

Do you think she'll take over the biz some day when you decide to retire?

--
Regards, Joerg

http://www.analogconsultants.com/
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Reply to
Joerg

Sweet, do you use Hyperlynx or whatever it's called to simulate voltage drops on planes?

Reply to
a7yvm109gf5d1

Gee, lots of wasted space, and it looks like only two layers for the most part (the tan colored area). I'd guess that board could be about half size if you wanted to?

Tim

Reply to
Tim Williams

I don't think I'll _decide_ to retire. But I offered it to her and she thought about it for about 19 milliseconds and said yes.

I have a technical guy I might involve, too. All I want is a desk and a workbench over in the corner, and a lucrative buyout contract.

John

Reply to
John Larkin

The plane DC drops are small and don't matter. I do need to keep AC ground loops out of the ADC section. I used TXline and Appcad to calculate trace impedances. The PCIexpress signal pairs need to be exact differential impedances and matched lengths, and PADS reports the routed lengths. I tweaked the more critical high-speed stuff, clock traces, impedances, bypassing, stuff like that, myself. It's hard to explain that part to a layout person, especially when it's half instinct anyhow.

John

Reply to
John Larkin

It could be smaller, but it's sort of connector dominated. It's 8 layers: four routing, one ground, three power plane layers. The horrible part is getting in/out of the FPGA; everything converges there.

It doesn't show, but the left side of the board is very trace+via dense on all layers. I like PCB layout; it's sort of a video game.

John

Reply to
John Larkin

On a sunny day (Fri, 16 Oct 2009 17:48:23 -0700) it happened John Larkin wrote in :

Yea, but does it work?

Reply to
Jan Panteltje

Spartan 6 looks nice. Too bad they don't come in PQ208 packages.

Well, some people can do PCB layouts and others can't.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
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Reply to
Nico Coesel

Great!

Probably to get the money for the Jeep back that she bought from your generous college funding :-)

Maybe they let you set up one of the Tek sampling scopes at Zeitgeist ...

--
Regards, Joerg

http://www.analogconsultants.com/
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Reply to
Joerg

It's not built yet. Of course it will work, hopefully the rev A etch.

John

Reply to
John Larkin

We've come to prefer BGA packages. Placement/soldering yield is better than leaded parts. In fact, we've had zero BGA problems, if you don't count the one that was placed 90 degrees off.

John

Reply to
John Larkin

On a sunny day (Mon, 19 Oct 2009 13:35:12 -0700) it happened John Larkin wrote in :

Once I designed a circuit with some digital and also some analog audio on it. Gave the diagram to a (very good actually) PCB design house, for prototype print. When testing it found a noise from the digital in the audio. The differential audio lines were not kept together (as I told them to do), but one went for a detour.... It is very difficult if you are not an electronics designer very familiar with the circuit's operation to make a good PCB. psychology and softball does not help a bit, may work for digital, to a point, but for very low level signals it would be a real miracle if it all worked as intended. Same for RF stuff. And [talking of miracles] again I did not win the lotto!

Reply to
Jan Panteltje

Thanks so much for providing ample data for a troll-feeder filter.

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

If your intention is not just to filter out people you class as "liberals", but also anyone who ever replies to someone who you think is a "liberal"...

I think you'll find that is pretty much everyone :)

--

John Devereux
Reply to
John Devereux

print.

Thou shalt not release a design without at least a final Gerber check.

I have a very seasoned layouter but still we go through 5-10 rounds of Gerber checks on every layout. Minor stuff but needs to be done. It's so easy for an important drill size or something to fall through the cracks.

--
Regards, Joerg

http://www.analogconsultants.com/
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Reply to
Joerg

print.

Yes. That's why the circuit designer must stay very close to the layout.

We pass PCB file ownership back and forth, and talk about things a lot. I'd do that with any layout person. I re-routed the PCIe lines and a bunch of clocks, and did the power switcher section myself, and played around with the bypassing. Two more people will review the schematic and layout, too. This board is a real mix of technologies and functions.

Even when you win you usually lose. It's designed that way.

John

Reply to
John Larkin

Of course you fail to note that some troll feeders also provide some sound engineering advice on occasion. My filter "simply" (:-) discerns when the normally cogent individual has decided to stray and feed the troll, then deletes that post only.

That takes more than Agent's standard filters, requiring a macro (script) to tell the difference.

I'm also happy to admit that many of you don't like my politics, but I don't care... in your whole lifetime you'll _never_ catch up to the number of successful designs I've done.

So back to your books, and pray a lot to Dear Leader Obama to subsidize your worthless asses ;-) ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

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