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I am using the latest greatest Windows install of ModelSim SE. I have compiled all the ISE and EDK simulation libraries using the tools in command line mode. That is another story all together, but the wizard in the EDk did NOT work. I kept getting errors. Anyways, all the libraries are compiled with NO errors. I then ran the 'Generate Simulation Files' in the EDk and everything finishes OK. All the files are created and placed in the simulation/behavioral directory. The top level is system.v so I start ModelSim and change directories to my EDK project/simulation/behavioral directory. I then run 'do system.do' at the ModelSim prompt. It goes through the process and reports everything OK. Then I type in 'vsim system system_conf glbl' from the ModelSim prompt. It runs through the process and gives errors. The errors are given for my custom IP cores located in the pcores directory. These cores instantiate Xilinx primitives (FDCPE's, DCM's, IDELAY's, etc) in their Verilog code. The errors say that those primitives are not defined. An example is: C:/<project directory>/pcores/clock_generator_v1_00_a/hdl/verilog/ dcm6x.v(76): Module 'DCM_ADV' is not defined. It appears that ModelSim cannot resolve these back to the compiled libraries. Everything else is OK. All the libraries are listed in ModelSim's workspace window. Is there something I am missing with respect to using the custom IP cores? Do I need to add a flag to the vsim command? Thanks!Article: 115651
> work. I can imagine that John J. may well also. When you're aiming
> at 100+dB isolation among traces, you do have to be pretty careful,
> even at "low" frequencies.
>
> Cheers,
> Tom- Hide quoted text -
>
> - Show quoted text -
______________________________________
Its all theory . If its open , the RF will leak
out . Like the holes in a MicroWave dish
----------------
10:1 SWR , open lines ,
and NO radiation .
-------------------
Transmission lines repulse , but that
does NOT mean magnetic fringing
and sending mag flds everywhere .
----------------------
BTW
Study CAT5e Ethernet cable .
garbage !
USB cables are much faster .
I think ppl limit themselves to
whats avail in PCB , then complain
when it dont work , but if they'd
experiment , they'd find the problem
is using thin PCB .
Then they limit on putting down
100 transmission lines per mm .
You cant learn , unless you experiment.
you can't choke the dimensions
and get good results , a transmission
line needs exact dimensions , or you
lose .
In coax for 2.5 Ghz , for example ,
it WILL have a large diameter and
the center will have an exact dia and
ratio .. No substitutes .
Sending signals that will be amplified
use high Z ( ~65 ohms ) and
sending power needs low Z .
These rules can't be bent .
Thats what you're doin , is bending
rules ...
.
Article: 115652On Feb 13, 7:51 am, John Larkin <jjlar...@highNOTlandTHIStechnologyPART.com> wrote: > On Tue, 13 Feb 2007 20:46:04 +1300, Jim Granville > > > > > > <no.s...@designtools.maps.co.nz> wrote: > >werty wrote: > >> On Feb 12, 2:30 pm, "john jardine" <j...@jjdesigns.fsnet.co.uk> wrote: > > >>>"Geronimo Stempovski" <geronimo.stempov...@arcor.de> wrote in message > > >>>news:45d04b34$0$27624$9b4e6d93@newsspool2.arcor-online.net...> I think transmitting high-speed signals is very easy when you have a > > >>>>360-degree ground reference, round conductors, > >>>>and no other nearby signals like in coaxial cables. My aim is to design > > >>>PCB > > >>>>tracks as much like a coaxial cable as > >>>>possible. Anyone tried this before? Is it possible with regular FR4, > > >>>anyway? > > >>>>Thanks for your help. > > >>>>Gero > > >>>Had trouble with crosstalk on a mass of video signals. Cured with a > >>>multilayer board where each signal was 'boxed in' by ground plane to the > >>>sides, above and below. Sort of square coax. > > >> ---------------------------------------------------------- > > >> Boxed ! the wavelength is far greater than > >> your dimensions , thus higher modes can not > >> exist , thus you do NOT need sides . > >> When you reach 10 Ghz , then maybe > >> you need sides in ur boxed "coax" . > ><snip> > > >Seems video distribution is not one of your areas of expertise ? > > > Note that John was talking about crosstalk, in the analog domain, > >and yes, what he did certainly will have a measurable improvement, and > >is somewhat 'industry practise' when minimising crosstalk. > > Note he says 'cured', that means he is on both sides of the problem, > >and it is a brave (or something else?) person that counters such direct > >experience > > >I imagine in extreme digital cases, such as where you are worried not > >only about sending the clock, but also about the ps/fs of jitter, then > >this design approach would also help : it's not hard to do. > > >-jg > > I do stuff down to a few ps RMS jitter on a regular 6 or 8-layer > board, microstrip traces, with switching supplies and uPs and display > drivers on the same board. Picoseconds aren't tough these days. > > John- Hide quoted text - > > - Show quoted text - ____________________________________ You are hoping that we believe switchers cause lots of noise .... Zero ripple is what switchers do ! The sudden pulse of current is only around a very short loop , it does not cause noise . They dont even have "ground loops"Article: 115653
"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> schrieb im Newsbeitrag news:fkt8t25shgq88ejbi56j4ubcaahnlntp3c@4ax.com... > > But FR-4 varies a lot, so there's no definitive data. > > What are you trying to do? > Hi John, I'm trying to compare several loss tangent values (I think that's the decisive parameter..!?) from several materials, FR4-, PE, etc. over the frequency. But it's hard to find such diagrams.Article: 115654
> Do you have Lattice tools there ? I'd also suggest taking a look at Lattice and the new ECP2M parts. Ricky.Article: 115655
Am I the only one who finds him tiring? I guess it would be funny if I wasn't using so many Xilinx parts. Ricky. On Feb 15, 6:10 pm, Austin <aus...@xilinx.com> wrote: > Tim, > > Well, that is odd, because we have ES material in stock (for V5). > > In the V5 program, we have met, or met early every public date we gave. > > After the V4 issues with FX MGT, we promised ourselves to never do that, > ever. Never. Ever. So, if you are with-holding your vote because of > your V4FX experience, we apologise, and promise to do much better (and > are doing much better). > > Peter and I have personally helped a few folks get their hands on their > V5 ES parts, when it seemed that the distributors had failed them. If > your distributor has failed you, we want to know. > > As to who you want to vote for, you can always vote (in another beauty > contest) for the "most innovative product in 2006 -- the Stratix III." > (Note, quotes are from a press release!). That is a good one: the > product will sample in September, 2007.... > > Of course, it is a free Internet, and the chip you should vote for is > the one that best fit the criteria as you decide. > > AustinArticle: 115656
spartan3wiz wrote: > On Feb 15, 1:03 pm, David Brown <d...@westcontrol.removethisbit.com> > wrote: >> Nico Coesel wrote: >>> "llandre" <llan...@libero.it> wrote: >>>> In this message >>>> http://groups.google.it/group/comp.arch.fpga/browse_thread/thread/4b6... >>>> Josh Rosen provided detailed information about comparative performance >>>> tests he made (see alsohttp://www.polybus.com/linux_hardware/ >>>> index.htm). >>>> When he posted that message AMD processors were definitively the best >>>> choiche. Did something changed since then? Have Intel processors >>>> released in the meanwhile filled the gap? >>> Based on 10 years of experience I recommend to stay away from AMD >>> based system for any serious computing. AMD based systems are low >>> budget systems based on crappy chipsets and crappy components and >>> because of that they lack a very important feature: stability. I've >>> never seen an AMD based system survive a day in the office without >>> crashing. Most people will tell you their AMD system _at home_ works >>> perfectly. But tell me, is a PC at home used extensively for 10 hours >>> straight? I don't think so. >> That may have had some merit as an argument 10 years ago, but it is >> totally at odds with most people's experiences since then. AMD has been >> the manufacturer of choice for serious computing since the Opteron's >> first came out - again and again, they have given more powerful and >> scalable than Intel's solutions, and the processors left stability >> problems behind with the K6 generation. There have been issues with >> heat - many of AMD's chips in the last five years have run particularly >> hot, and if you buy a cheap system then it's cooling system might not be >> good enough. And if you want to talk about motherboard and chipset >> issues, then Intel has far outweight AMD for problems in recent years - >> mostly because, until the Core 2, it has been rushing out everything it >> can in hopes of competing with AMD. >> >> In my own experience, I have picked AMD on almost every occasion in the >> last fifteen years - first purely for value for money, and later for >> reliability as well. Were I buying a new machine today, I would >> probably go for a Dual Core 2, simply because of better value for money >> at the moment, although for a server I might pick AMD for stability (and >> for a four-core or more machine, AMD is the only realistic choice). >> >> If your machines crash after a day at the office, you are doing >> something terribly wrong, and the processor is the least of your >> worries. Most of the machines I use and administer, at home and at the >> office, are AMD's, and most of them are never turned off. I have a >> server here at the office with a 300 MHz AMD K6 that has been running >> for around 8 years, and has only been off a half-dozen times for power >> cuts and a replacement power supply (this is probably a world record for >> NT 4.0). >> >> And in the world of gaming, people run their machines for much longer >> than 10 hours at a time, and often with more demanding loads than any >> professional use - they generally choose AMD. >> >> There is a reason why AMD captured a large proportion of the server >> market, especially for multi-core systems, despite Intel's entrenchment >> (and illegal and/or unethical behaviour, for which they are currently on >> trial). >> >>> If you want a computer get an Intel cpu based professional workstation >>> from the business section from Dell or HP. You'll probably notice the >>> price difference between the computer shop around the corner, but >>> believe me, the price difference is worth having a PC that just works >>> fine every day. Large companies buy PCs like these by the thousands >>> for a good reason: a PC which doesn't work/crashes costs a lot of >>> money. >> This is a totally different issue. If you want a reliable machine, be >> prepared to spend money on it and get it from a reliable supplier. No >> one will argue with that. Don't buy AMD processors because they are >> cheap - buy the appropriate chip for the job. > > There is a major risk for me missing the point here, but I'll give it > ago anyway! The original question takled about the ISE and Dual > Cores.... why would you need Dual Core for ISE? It does never use more > than one of them anyway! OK it'll give your windows/Linux better > response for other things while running ISE but it will NOT speed up > the actual Synthesis+P&R action. Have any of you guys had ANY luck > with using the "second" one within ISE? Maybe someone from Xilinx care > to answer. If my memory serves me Xilinx made a statement that the ISE > 8.1 would add support for Dual-Cores when running the tools. OK i > gogled for that too.. http://www.eeproductcenter.com/pld-fpga/ > showArticle.jhtml?articleID=174918452 > > I did NOT notice any improvement between 7.1 and 8.1 using my AMD > 3800+ X2 when building a bigger project (a big project for me is a > project that fills my S3 StarterKit 200K). It actually got slower! And > now in ISE 9.1 (webpack) I did not see any signs of the normal ISE > toolchain having any support at all for Dual Cores? I did a more > through post here: http://www.journalforums.com/cgi-bin/ikonboard.cgi? > act=ST;f=1;t=57 > that you can read and comment on here in this newsgroup. > The Intel Dual Core 2 chips are about the fastest available cpus at the moment, at least for sensible prices. I've heard several times that fpga tools like larger caches, which these chips have. The fact that you have two cores is almost incidental for ISE at the moment. However, there are always a few things going on in the background while waiting for a place and route - the second core can save you as much as a step up in clock speed even if you are not using the computer for anything else. There is also the future to look to - Quartus now has partial parallelism, and can use two cores for part of the work. It might only save something like 10-20% time at the moment, but we can look forward to competition between X and A in the race to get more parallelism out of their tools.Article: 115657
Hi there, I've heard that some Lattice FPGAs support M-LVDS signalling. Did anyone has any experience with lattice M-LVDS? Are they true M-LVDS driver/receivers? What are the deviations from the TIA/EIA-899 specification? Finally are They current-mode drivers? Thanks.Article: 115658
Tim <tim@nooospam.roockyloogic.com> wrote: > If you, or anyone else in Xilinx, would like to improve matters, could > you please publish a comprehensive price and availability list for the > various families. Then the poor old working engineer can make a > cost/benefit/risk analysis - after all, that's what you want your > customers to do before setting forth on designs. To get an idea what information is needed, take a look at the Texas Instruments webpage and go to a particular device, like the just announced ADS5231 and follow the links to the part to reach e.g. http://focus.ti.com/docs/prod/folders/print/ads5231.html You find - package option - budget price - Inventory - Lead time - distributors (if any yet) - and a sample request entry -- Uwe Bonnes bon@elektron.ikp.physik.tu-darmstadt.de Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt --------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------Article: 115659
On 15 Feb 2007 22:26:30 -0800, "werty" <werty@swissinfo.org> Gave us: >On Feb 13, 7:51 am, John Larkin ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> On Tue, 13 Feb 2007 20:46:04 +1300, Jim Granville >> >> >> >> >> >> <no.s...@designtools.maps.co.nz> wrote: >> >werty wrote: >> >> On Feb 12, 2:30 pm, "john jardine" <j...@jjdesigns.fsnet.co.uk> wrote: >> >> >>>"Geronimo Stempovski" <geronimo.stempov...@arcor.de> wrote in message >> >> >>>news:45d04b34$0$27624$9b4e6d93@newsspool2.arcor-online.net...> I think transmitting high-speed signals is very easy when you have a >> >> >>>>360-degree ground reference, round conductors, >> >>>>and no other nearby signals like in coaxial cables. My aim is to design >> >> >>>PCB >> >> >>>>tracks as much like a coaxial cable as >> >>>>possible. Anyone tried this before? Is it possible with regular FR4, >> >> >>>anyway? >> >> >>>>Thanks for your help. >> >> >>>>Gero >> >> >>>Had trouble with crosstalk on a mass of video signals. Cured with a >> >>>multilayer board where each signal was 'boxed in' by ground plane to the >> >>>sides, above and below. Sort of square coax. >> >> >> ---------------------------------------------------------- >> >> >> Boxed ! the wavelength is far greater than >> >> your dimensions , thus higher modes can not >> >> exist , thus you do NOT need sides . >> >> When you reach 10 Ghz , then maybe >> >> you need sides in ur boxed "coax" . >> ><snip> >> >> >Seems video distribution is not one of your areas of expertise ? >> >> > Note that John was talking about crosstalk, in the analog domain, >> >and yes, what he did certainly will have a measurable improvement, and >> >is somewhat 'industry practise' when minimising crosstalk. >> > Note he says 'cured', that means he is on both sides of the problem, >> >and it is a brave (or something else?) person that counters such direct >> >experience >> >> >I imagine in extreme digital cases, such as where you are worried not >> >only about sending the clock, but also about the ps/fs of jitter, then >> >this design approach would also help : it's not hard to do. >> >> >-jg >> >> I do stuff down to a few ps RMS jitter on a regular 6 or 8-layer >> board, microstrip traces, with switching supplies and uPs and display >> drivers on the same board. Picoseconds aren't tough these days. >> >> John- Hide quoted text - >> >> - Show quoted text - > >____________________________________ > > You are hoping that we believe switchers > cause lots of noise .... > > Zero ripple is what switchers do ! > The sudden pulse of current is only > around a very short loop , it does > not cause noise . > They dont even have "ground loops" > > We cannot use switchers to feed to rails on our 2 to 12 GHz designs. NOISE CAN AND DOES get injected into such systems BY SWITCHING POWER SUPPLIES. YOU may not be aware of it, but those of us that work in such bands are aware of high frequency switching noise, and it DOES show up under spectrum analysis. Your brain has a ground loop.Article: 115660
> >Cores.... why would you need Dual Core for ISE? It does never use more > >than one of them anyway! > > Because the fast (2.4GHz and above) Core 2 Duo chips get you 4MB of > level-2 cache which, if you're using ISE on only one core and not > doing anything very intensive in the background, is all available to > the ISE process. Given how much of a boost people saw with 1MB-cache > versus 512k-cache AMD chips, and how memory-intensive FPGA compilation > is, I would expect 4MB to be distinctly useful. Also the machine I'm going to buy will be occasionally used by two people working on two different FPGA projects at the same time. Since they will run two different ISE istances, I expect they will be benefit from the dual core cpu. Is this speculation reasonable?Article: 115661
On Fri, 16 Feb 2007 09:54:47 +0100, David Brown wrote: > spartan3wiz wrote: >> On Feb 15, 1:03 pm, David Brown <d...@westcontrol.removethisbit.com> >> wrote: >>> Nico Coesel wrote: >>>> "llandre" <llan...@libero.it> wrote: >>>>> In this message >>>>> http://groups.google.it/group/comp.arch.fpga/browse_thread/thread/4b6... >>>>> Josh Rosen provided detailed information about comparative performance >>>>> tests he made (see alsohttp://www.polybus.com/linux_hardware/ >>>>> index.htm). >>>>> When he posted that message AMD processors were definitively the best >>>>> choiche. Did something changed since then? Have Intel processors >>>>> released in the meanwhile filled the gap? >>>> Based on 10 years of experience I recommend to stay away from AMD >>>> based system for any serious computing. AMD based systems are low >>>> budget systems based on crappy chipsets and crappy components and >>>> because of that they lack a very important feature: stability. I've >>>> never seen an AMD based system survive a day in the office without >>>> crashing. Most people will tell you their AMD system _at home_ works >>>> perfectly. But tell me, is a PC at home used extensively for 10 hours >>>> straight? I don't think so. >>> That may have had some merit as an argument 10 years ago, but it is >>> totally at odds with most people's experiences since then. AMD has been >>> the manufacturer of choice for serious computing since the Opteron's >>> first came out - again and again, they have given more powerful and >>> scalable than Intel's solutions, and the processors left stability >>> problems behind with the K6 generation. There have been issues with >>> heat - many of AMD's chips in the last five years have run particularly >>> hot, and if you buy a cheap system then it's cooling system might not be >>> good enough. And if you want to talk about motherboard and chipset >>> issues, then Intel has far outweight AMD for problems in recent years - >>> mostly because, until the Core 2, it has been rushing out everything it >>> can in hopes of competing with AMD. >>> >>> In my own experience, I have picked AMD on almost every occasion in the >>> last fifteen years - first purely for value for money, and later for >>> reliability as well. Were I buying a new machine today, I would >>> probably go for a Dual Core 2, simply because of better value for money >>> at the moment, although for a server I might pick AMD for stability (and >>> for a four-core or more machine, AMD is the only realistic choice). >>> >>> If your machines crash after a day at the office, you are doing >>> something terribly wrong, and the processor is the least of your >>> worries. Most of the machines I use and administer, at home and at the >>> office, are AMD's, and most of them are never turned off. I have a >>> server here at the office with a 300 MHz AMD K6 that has been running >>> for around 8 years, and has only been off a half-dozen times for power >>> cuts and a replacement power supply (this is probably a world record for >>> NT 4.0). >>> >>> And in the world of gaming, people run their machines for much longer >>> than 10 hours at a time, and often with more demanding loads than any >>> professional use - they generally choose AMD. >>> >>> There is a reason why AMD captured a large proportion of the server >>> market, especially for multi-core systems, despite Intel's entrenchment >>> (and illegal and/or unethical behaviour, for which they are currently on >>> trial). >>> >>>> If you want a computer get an Intel cpu based professional workstation >>>> from the business section from Dell or HP. You'll probably notice the >>>> price difference between the computer shop around the corner, but >>>> believe me, the price difference is worth having a PC that just works >>>> fine every day. Large companies buy PCs like these by the thousands >>>> for a good reason: a PC which doesn't work/crashes costs a lot of >>>> money. >>> This is a totally different issue. If you want a reliable machine, be >>> prepared to spend money on it and get it from a reliable supplier. No >>> one will argue with that. Don't buy AMD processors because they are >>> cheap - buy the appropriate chip for the job. >> >> There is a major risk for me missing the point here, but I'll give it >> ago anyway! The original question takled about the ISE and Dual >> Cores.... why would you need Dual Core for ISE? It does never use more >> than one of them anyway! OK it'll give your windows/Linux better >> response for other things while running ISE but it will NOT speed up >> the actual Synthesis+P&R action. Have any of you guys had ANY luck >> with using the "second" one within ISE? Maybe someone from Xilinx care >> to answer. If my memory serves me Xilinx made a statement that the ISE >> 8.1 would add support for Dual-Cores when running the tools. OK i >> gogled for that too.. http://www.eeproductcenter.com/pld-fpga/ >> showArticle.jhtml?articleID=174918452 >> >> I did NOT notice any improvement between 7.1 and 8.1 using my AMD >> 3800+ X2 when building a bigger project (a big project for me is a >> project that fills my S3 StarterKit 200K). It actually got slower! And >> now in ISE 9.1 (webpack) I did not see any signs of the normal ISE >> toolchain having any support at all for Dual Cores? I did a more >> through post here: http://www.journalforums.com/cgi-bin/ikonboard.cgi? >> act=ST;f=1;t=57 >> that you can read and comment on here in this newsgroup. >> > > The Intel Dual Core 2 chips are about the fastest available cpus at the > moment, at least for sensible prices. I've heard several times that > fpga tools like larger caches, which these chips have. The fact that > you have two cores is almost incidental for ISE at the moment. However, > there are always a few things going on in the background while waiting > for a place and route - the second core can save you as much as a step > up in clock speed even if you are not using the computer for anything > else. There is also the future to look to - Quartus now has partial > parallelism, and can use two cores for part of the work. It might only > save something like 10-20% time at the moment, but we can look forward > to competition between X and A in the race to get more parallelism out > of their tools. PAR in the Xilinx tools has been multithreaded for years as long as you run it on a *nix system.Article: 115662
Tim <tim@nooospam.roockyloogic.com> writes:
>If you think I'm exaggerating, try the Avnet site:
<...>
>Spartan-3E parts: prototype parts only and no higher volume pricing
And funny enough, Avnet gave us a first price estimation for quantity 1000 of an
1600E higher than the prototype price in their webshop. I don't know what they
are smoking...
--
Georg Acher, acher@in.tum.de
http://www.lrr.in.tum.de/~acher
"Oh no, not again !" The bowl of petunias
Article: 115663
On 2007-02-16, werty <werty@swissinfo.org> wrote:
> BTW
> Study CAT5e Ethernet cable .
> garbage !
> USB cables are much faster .
>
>
> I think ppl limit themselves to
> whats avail in PCB , then complain
> when it dont work , but if they'd
> experiment , they'd find the problem
> is using thin PCB .
> Then they limit on putting down
> 100 transmission lines per mm .
> You cant learn , unless you experiment.
Shite man, what are you using for a computer, a 40-column
Commodore PET?
[...]
> Sending signals that will be amplified
> use high Z ( ~65 ohms ) and
> sending power needs low Z .
> These rules can't be bent .
> Thats what you're doin , is bending
> rules ...
Even a PET wouldn't explain the random indentation.
--
Grant Edwards grante Yow! Remember, in 2039,
at MOUSSE & PASTA will
visi.com be available ONLY by
prescription!!
Article: 115664On 2007-02-16, General Schvantzkoph <schvantzkoph@yahoo.com> wrote: > PAR in the Xilinx tools has been multithreaded for years as long as > you run it on a *nix system. Are you thinking about the -m option to par? Because that is really only useful if you need to run par several times on a design and pick the best design as far as I understand it. So you will not really speed up par but you might get a little better results out of it. According to the documentation only the cost table entry is varied for each run so you should be able to do essentially the same thing in Windows by running par with different -t options on a number of Windows machines. /AndreasArticle: 115665
I can build other designs and have them work using the ACE CF, however the GSRD does not seem to kick off the software application. I'm very frustrated - is there an issue loading the external ddram through the mpmc? I'm using gsrd v7.1 w/edk 7.1 Any ideas?Article: 115666
Grant Edwards <grante@visi.com> writes: > On 2007-02-16, werty <werty@swissinfo.org> wrote: > >> BTW >> Study CAT5e Ethernet cable . >> garbage ! >> USB cables are much faster . >> >> >> I think ppl limit themselves to >> whats avail in PCB , then complain >> when it dont work , but if they'd >> experiment , they'd find the problem >> is using thin PCB . >> Then they limit on putting down >> 100 transmission lines per mm . >> You cant learn , unless you experiment. > > Shite man, what are you using for a computer, a 40-column > Commodore PET? > > [...] > >> Sending signals that will be amplified >> use high Z ( ~65 ohms ) and >> sending power needs low Z . >> These rules can't be bent . >> Thats what you're doin , is bending >> rules ... > > Even a PET wouldn't explain the random indentation. And the random word and punctuation spacing. Some kind of mobile phone? The Microsoft Word Usenet Export Filter? I think it's the usenet equivalent of green ink. <http://en.wikipedia.org/wiki/Green_ink> -- John DevereuxArticle: 115667
On Fri, 16 Feb 2007 08:01:13 +0100, "Geronimo Stempovski" <geronimo.stempovski@arcor.de> wrote: > >"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> schrieb im >Newsbeitrag news:fkt8t25shgq88ejbi56j4ubcaahnlntp3c@4ax.com... >> >> But FR-4 varies a lot, so there's no definitive data. >> >> What are you trying to do? >> > >Hi John, I'm trying to compare several loss tangent values (I think that's >the decisive parameter..!?) from several materials, FR4-, PE, etc. over the >frequency. But it's hard to find such diagrams. > No, what are you trying to *do*? WHY do you want a "coax on a pc board"? JohnArticle: 115668
On 2007-02-16, John Devereux <jdREMOVE@THISdevereux.me.uk> wrote:
> Grant Edwards <grante@visi.com> writes:
>
>> On 2007-02-16, werty <werty@swissinfo.org> wrote:
>>
>>> BTW
>>> Study CAT5e Ethernet cable .
>>> garbage !
>>> USB cables are much faster .
>>>
>>>
>>> I think ppl limit themselves to
>>> whats avail in PCB , then complain
>>> when it dont work , but if they'd
>>> experiment , they'd find the problem
>>> is using thin PCB .
>>> Then they limit on putting down
>>> 100 transmission lines per mm .
>>> You cant learn , unless you experiment.
>>
>> Shite man, what are you using for a computer, a 40-column
>> Commodore PET?
>>
>> [...]
>>
>>> Sending signals that will be amplified
>>> use high Z ( ~65 ohms ) and
>>> sending power needs low Z .
>>> These rules can't be bent .
>>> Thats what you're doin , is bending
>>> rules ...
>>
>> Even a PET wouldn't explain the random indentation.
>
> And the random word and punctuation spacing. Some kind of mobile
> phone? The Microsoft Word Usenet Export Filter?
>
> I think it's the usenet equivalent of green ink.
>
><http://en.wikipedia.org/wiki/Green_ink>
I love it! I'd never heard the phrase "green ink" before. It's
a keeper.
--
Grant Edwards grante Yow! Now, I think it would
at be GOOD to buy FIVE or SIX
visi.com STUDEBAKERS and CRUISE for
ARTIFICIAL FLAVORING!!
Article: 115669George Acher posted on Fri, 16 Feb 2007 13:12:14 +0000 (UTC): "And funny enough, Avnet gave us a first price estimation for quantity 1000 of a n 1600E higher than the prototype price in their webshop. I don't know what they are smoking..." I checked the price of a component (not an F.P.G.A. though) we needed on a few websites in December 2006. One of them was Avnet's and Avnet's website had the engineering (prototype, commercial quality) model priced at $11122.80 whereas Avnet's website had the radiation hardened space qualified (better quality) version priced much less at $3738. I performed this search due to miscommunication: we had actually already bought the radiation hardened version before December for far less than $5000 (though I do not know for how much exactly, nor from whom).Article: 115670
On 15 Feb 2007 22:22:50 -0800, "werty" <werty@swissinfo.org> wrote: > In coax for 2.5 Ghz , for example , > it WILL have a large diameter and > the center will have an exact dia and > ratio .. No substitutes . Never heard of micro hardline, I guess. Or non-TEM propagation modes in large-diameter coax. JohnArticle: 115671
On 15 Feb 2007 22:26:30 -0800, "werty" <werty@swissinfo.org> wrote: >On Feb 13, 7:51 am, John Larkin ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote: >> On Tue, 13 Feb 2007 20:46:04 +1300, Jim Granville >> >> >> >> >> >> <no.s...@designtools.maps.co.nz> wrote: >> >werty wrote: >> >> On Feb 12, 2:30 pm, "john jardine" <j...@jjdesigns.fsnet.co.uk> wrote: >> >> >>>"Geronimo Stempovski" <geronimo.stempov...@arcor.de> wrote in message >> >> >>>news:45d04b34$0$27624$9b4e6d93@newsspool2.arcor-online.net...> I think transmitting high-speed signals is very easy when you have a >> >> >>>>360-degree ground reference, round conductors, >> >>>>and no other nearby signals like in coaxial cables. My aim is to design >> >> >>>PCB >> >> >>>>tracks as much like a coaxial cable as >> >>>>possible. Anyone tried this before? Is it possible with regular FR4, >> >> >>>anyway? >> >> >>>>Thanks for your help. >> >> >>>>Gero >> >> >>>Had trouble with crosstalk on a mass of video signals. Cured with a >> >>>multilayer board where each signal was 'boxed in' by ground plane to the >> >>>sides, above and below. Sort of square coax. >> >> >> ---------------------------------------------------------- >> >> >> Boxed ! the wavelength is far greater than >> >> your dimensions , thus higher modes can not >> >> exist , thus you do NOT need sides . >> >> When you reach 10 Ghz , then maybe >> >> you need sides in ur boxed "coax" . >> ><snip> >> >> >Seems video distribution is not one of your areas of expertise ? >> >> > Note that John was talking about crosstalk, in the analog domain, >> >and yes, what he did certainly will have a measurable improvement, and >> >is somewhat 'industry practise' when minimising crosstalk. >> > Note he says 'cured', that means he is on both sides of the problem, >> >and it is a brave (or something else?) person that counters such direct >> >experience >> >> >I imagine in extreme digital cases, such as where you are worried not >> >only about sending the clock, but also about the ps/fs of jitter, then >> >this design approach would also help : it's not hard to do. >> >> >-jg >> >> I do stuff down to a few ps RMS jitter on a regular 6 or 8-layer >> board, microstrip traces, with switching supplies and uPs and display >> drivers on the same board. Picoseconds aren't tough these days. >> >> John- Hide quoted text - >> >> - Show quoted text - > >____________________________________ > > You are hoping that we believe switchers > cause lots of noise .... > > Zero ripple is what switchers do ! > The sudden pulse of current is only > around a very short loop , it does > not cause noise . > They dont even have "ground loops" > > > > Please post the schematic of a zero-ripple switcher. JohnArticle: 115672
Jim Granville posted on Fri, 16 Feb 2007 13:56:22 +1300:
"Peter Alfke wrote:
> Do you like Virtex-5 ? Then please vote for it...
>
> The editors of Electronic Design News think Virtex-5 is an innovative
> product;
> they have nominated for their 17th Annual EDN Innovation Awards:
>
> the Xilinx Virtex-5 Design Team for "Innovator of the Year," and
>
> the Virtex-5 LXT platform for "Innovation of the Year" (in the
> Digital ICs category)
>
[..]
They also miss a [none of the above] vote, so readers cannot indicate
if they agree with the shortlists."
A very good point.
"Digital ICs, programmable logic, and memory:
PEX 8548 PCI Express switch (PLX Technology)
MR2A16A MRAM (Freescale)
Virtex-5 LXT FPGAs (Xilinx)
and since the award is for innovation :
Adj.
1. innovative - ahead of the times;
2. innovative - being or producing something like nothing done or
experienced or created before;
then the clear winner (by a large margin) is the MRAM.
That's far closer to innovative than "another iteration in FPGAs" ?"
Nah, the concept of randomness was mentioned hundreds of years ago but
called "chaos".
It would be great to have Jim Granville as a reviewer for what passes
as research in Europe: I attended doctoral workshops here in which
many of the abstracts were written with the word "innovative" or
"novel" to describe something which is a minor adaptation of existing
work, and many of the abstracts were written as if it is amazing that
civilization even managed to survive before the brilliant Ph.D. candidate
managed to come up with something which will supposedly change the
world.
Sincerely,
Colin Paul Gloster
Article: 115673"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> schrieb im Newsbeitrag > > No, what are you trying to *do*? WHY do you want a "coax on a pc > board"? > Ah, okay, what I am actually trying to find out is what makes FR4 act worse than e.g. teflon at data rates beyond 2,5 Gbps. Is it the loss tangent or the epsilon r? How is the frequency-dependent attenuation physically describable? Where does the energy go? Heat, ...? It was my opinion that higher frequencies can be transmitted over coax but not over FR4 because of the geometry. Because in a coax there is (almost) no energy loss because the TEM wave is "captured" by the outer shield and in a planar setup like stripline or microstrip there are E-field and H-field lines vanish into the air environment (or somewhere else...). Therefore I'm trying to design a coax on a PCB. Am I right with my thoughts, anyway?Article: 115674
On Fri, 16 Feb 2007 18:58:54 +0100, "Geronimo Stempovski" <geronimo.stempovski@arcor.de> wrote: > >"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> schrieb im >Newsbeitrag > >> No, what are you trying to *do*? WHY do you want a "coax on a pc >> board"? >> > >Ah, okay, what I am actually trying to find out is what makes FR4 act worse >than e.g. teflon at data rates beyond 2,5 Gbps. Is it the loss tangent or >the epsilon r? How is the frequency-dependent attenuation physically >describable? Where does the energy go? Heat, ...? It was my opinion that >higher frequencies can be transmitted over coax but not over FR4 because of >the geometry. Because in a coax there is (almost) no energy loss because the >TEM wave is "captured" by the outer shield and in a planar setup like >stripline or microstrip there are E-field and H-field lines vanish into the >air environment (or somewhere else...). Therefore I'm trying to design a >coax on a PCB. Am I right with my thoughts, anyway? > A couple of things make pcb's lossy: the loss tangent of the material (and FR4 is pretty bad) and the copper losses. Copper loss gets bad on conventional FR4 boards because 1. FR4's Er is high, so for a given impedance traces are skinny. 2. The underside of the copper is treated to bond to the epoxy/glass, and the treatment (black oxide or something) greatly increases skin losses. Peel some up and look... it's gross. 3. In the case of microstrip, the current is concentrated on the underside (the dirty side) of the trace, so losses are that much worse... the shiny topside of the copper is underutilized. Stripline would be better, with balanced current density, except that the trace will be much thinner, which has its own penalty. A good microwave pcb has a low Er, low loss dielectric; is thick, for low current density and wide traces; has very smooth copper, which means traces and pads peel off easily. I don't think any simple geometry tricks (ie, emulating coax) will make FR4 any better, and would probably make it worse. For low losses, microstrip on a thick board is probably as good as it gets. John
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