Agree. It takes a bit more to cross the line and usually you only see that in areas such as medical or politics. Invitations to ritzy resorts for a "seminar", and oh yeah, of course the family can tag along.
-- Regards, Joerg http://www.analogconsultants.com
Actually that's easy. It's modeling parts that DO exist, accurately, that's hard.
Ask your expert to run monte carlo over the temperature range using real parts, if he's going to get silly. Perhaps he just meant
22000 or 33000pF mjay very well look like 18000pF, in a crappy 10V or 6V dielectric at 3V or 5V.RL
Where are you located? If it's near San Francisco, I'll review your signal integrity for free. We mix microvolts and amps and picoseconds all the time.
John
Spice simulating a capacitor as a resonant LC, in free space, is useless as regards power plane design and bypassing. That doesn't keep it from being a popular sport.
If this is critical to you, plop a few SMA or H.FL coax footprints on the board layout to bring out plane voltages against ground. Or even pads you can solder a coax onto. Then you can TDR the unloaded board, then the bare board+bypass caps, and finally measure the noise on an operating board. Expect a lot of the problems to be caused by low-frequency noise, so an old Tek scope with a 7A22 plugin will resolve microvolts of noise up to 1 MHz. Most of our picosecond jitter drivers turn out to be low-frequency noise on power rails.
And borrow or rent a spectrum analyzer if frequency-domain stuff is critical.
Yup. And the planes themselves, and their losses, are dominant at high frequencies... enough to make Spice models of free-space capacitors meaningless.
So, if you don't fire this guy, at least don't delegate the whole thing to him. You have a lot more to lose then he does. Take control along a parallel path. And you *must* be intimately involved in the pcb layout.
John
We use Pads 5.0. Since it's perfect, any later versions must by definition be worse, so we quit upgrading. One hint was when they started offering courses to current PADS-LOGIC users so that they could learn how to drive the new version.
Ditto using PADS from the DOS days.
John
I should post our latest signal-integrity puzzle horror story, the one that involves the low-conductance diodes and hundreds of uA pouring out of CMOS gate input pins. We just fixed it.
John
The thinner the dielectric between a power pour and ground, the higher the plane-plane capacitance and the lower the high-frequency noise. The planes are the real hf bypasses, and the "bypass" caps only really supply the low-frequency currents, which is why they're not all that critical.
John
We used to, until we sent all our production to a CM. I used to do the purchasing and tracking production too, at least until my third nervous breakdown. I used to get samples and stuff but since we always sent out stuff out to be assembled anyways, we now let the CM sort out the mess.
There's yet another advantage to being a smoker. I can collect my butts, soak them, and spray the roses with the water. The aphids disappear almost instantly, and the plants perk up in a matter of hours. :-)
Cheers! Rich
Ok, I must have been thinking about the thickness of the plane itself. Since capacitance doesn't depend on that... just the area.
OT: With the crooked voting machines from Diebold, politics is so bad it's not even worth discussing:
Medicine is perhaps even worse:
"Nearly all US doctors have links with drug companies"
US and Australian researchers said in the study that 25 percent of doctors surveyed said they had received direct payments from pharmaceutical producers.
In addition, fully 94 percent of practicing doctors "have at least one type of relationship with the drug industry," though this most often means receiving food in the workplace or sample prescription drugs.
"Relationships with industry are a fundamental part of the way medicine is practiced today. The real questions relate to how much is too much and how far is too far," said a summary of the study released Wednesday.
The study, to be published in the April 26 issue of the New England Journal of Medicine, comes in the wake of several scandals in the health and research industries over conflicts of interest.
Last year, for instance, Dr Trey Sunderland of the US National Institutes of Health was shown to have received 285,000 dollars from Pfizer, the world's largest drug company, for cooperating with them without having informed his superiors at the government health research agency.
The study found that drug and medical device manufacturers single out doctors in certain areas and doctors with influence over others to develop close relationships, offering things like payments for consulting and honoraria for speaking engagements.
Cardiologists are a key target of the industry's consulting and other payments, in part because they can influence what drugs and devices other doctors choose, said lead researcher Eric Campbell of the Institute for Health Policy at Massachusetts General Hospital and Harvard Medical School.
"Cardiology is a highly influential specialty within the medical profession. If the drug and device industry can influence cardiologists, they can likely influence the prescribing practices of other doctors," said Campbell.
"It appears that these relationships benefit physicians and industry, but the important policy question is to what extent do these relationships benefit patients in the terms of the care they receive," he said.
The researchers note that more payments go to doctors who develop clinical guidelines and mentor other doctors in training than to other types of doctors.
"I know it's cliche, but if it didn't work, drug companies wouldn't do it," said David Blumenthal, director of the Institute for Health Policy.
"It appears pretty clear that industry forms tighter relationships with doctors who are really the thought leaders, the ones who are likely to affect the behavior of other doctors," Blumenthal said.
According to the summary, the authors of the study said their findings should "raise alarms" to do more to prevent health manufacturers from having too much influence over doctors.
The original article in the New England Journal of Medicine:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ It makes you wonder if these relationships have anything to do with the high cost of medicine. Here's an example:
"Uninsured patient billed more than $12,000 for broken rib"
There are 47 million people in this country without health insurance. Richmond resident Joey Palmer is one of them.
He learned how costly this can be after fracturing a rib in a relatively minor motorcycle accident and subsequently being hit with a bill for more than $12,000 from San Francisco General Hospital.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The cost directly affects health insurance. This was discussed here recently, and it is a serious problem.
"Health insurance options dwindle for self-employed"
Group plans are being dropped or becoming unaffordable to many.
A major source of health insurance for people who work for themselves is disappearing, casting thousands of contractors, freelancers and solo practitioners into the ranks of the uninsured with little hope of obtaining new coverage.
Regards,
Mike Monett
Once upon a time a tailor came before the emperor with a cloth that was woven so finely, he said, that only the wise could see it.
Bye. Jasen
Fight any move to have it run by the Feds. It should be run by the states, with the Feds just setting minimum benefits and providing part of the finances - like Canada.
When the USA was founded, if you got sick you mostly died. The doctors often made it worse - like Lincoln. This is something never contemplated by the founders.
Yeah, but the grass is not always greener on the other side. I have met Canadians who have come here to the US to get medical care which they either couldn't obtain in Canada or were on too long a waiting list. Out of pocket, they said there was some kind of law up there that they weren't allowed to take out a US policy for that. I guess that this boils down to basic care for regular folks but new cancer treatments only for rich folks.
But something needs to happen in the US, and soon. We can't have about
1/5th of the population without any health insurance at all and just play sitting duck.-- Regards, Joerg http://www.analogconsultants.com
I guess that was the case in pretty much all countries back then. Look at ancient death certificates: Died of an uncureable disease.
-- Regards, Joerg http://www.analogconsultants.com
For some of us its a lot closer to "Dead duck".
-- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
I guess it depends on the situation. I've hear of it happening, but my Mom and all her friends have had no problems getting care. They are all pretty old and have just about every problem you could imagine.
I guess it depends on the individual situation and where you live. Here in the small town of Midland, I had to wait a month for a CAT scan at the local hospital. But it wasn't critical, and if it were, I could have gone to Barrie which is only 45 minutes away.
As far as cancer, I believe about one-third are caused by viruses such as human papillomavirus, Epstein-Barr, etc. Google shows 44,900,000 hits for the words _cancer virus_.
But if you kill the virus, you kill the cancer. Silver is one of the very few substances that has any effect on viruses, and it has shown some very remarkable effects on some cancers. You might mention this to some of your doctor friends.
Agree. And in many cases, you have to take responsibility for your own health care.
Regards,
Mike Monett
Right. I don't have much sympathy for people moaning about their aches and lack of health care while they have let themselves slip into full-blown obesity. There are a lot of people who don't even know how to cook a simple meal. So they go to fast food places all the time, which also doesn't exactly help in prying themselves out of the typical humongous credit card debt. Pathetic.
-- Regards, Joerg http://www.analogconsultants.com
I thought the point was to kill aphids, not roses. Nicotine is, in fact, a natural insecticide that accidentally turned out to be addictive to humans.
Oh, don't get me wrong, smoking isn't the problem. Tobacco will cause cancer if you chew it, too. The secondary effects are just different; emphysema and heart disease if you smoke, gum necrosis and heart disease if you chew.
John
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