"Henry Kiefer" wrote in message
...
OK Jim -

I simulated your question in a first trial. Here is the result:
approx. 70MegHz resonance for 100pF, 30mOhm ESR and 5nH for the trace.
Surely I would prefer smd chips having better results.

But that wasn't the question. THe question was to simulate a 1000 pf (1 nf)
capacitor at 150 MHz. with an inch of lead or an inch of normal pcb trace
and tell me what you get.




BTW: I cannot understand why you're so aggressive and I would prefer that
the thread will go in direction of my FIRST posting.

OK by me.



I'm doing electronics
since I was 12 years old

8 years old.


and that is 25 years back.

54 years back.


I have for example a
patent application made

I've got a few more.



and worked in the communication industry.

38 years straight now.


So you can
surely think I know what I'm doing.

Then answer the question.

Jim

jw\ wrote...

The question was to simulate a 1000 pf (1 nf) capacitor at
150 MHz. with an inch of lead or an inch of normal pcb trace
and tell me what you get.

Such a question is stupid and incomplete. First of all, in
cases where impedance matters, one wouldn't dare use an inch
of lead at 150MHz, we'd cut that short, 0.1-inch max. And
we certainly wouldn't use an inch of pcb trace unless it was
field-controlled with a ground plane. This is true whether a
1nF cap is involved or not. If you were to insist on analyzing
an inch of lead, we'd insist on knowing *all* about the ground
scene. Since you aggressively put your question without any
relevant information about what the ground is like, and where
it is, the question is intrinsically-stupid and incomplete.

Sorry, jw\, but that's the way it is.

BTW: I cannot understand why you're so aggressive ...

Indeed.

Then answer the question.

Answered repeatedly already.


--
Thanks,
- Win

Mark wrote [WITHOUT CONTEXT]:
there are lots of parts...

http://groups.google.com/group/sci.electronics.design/browse_frm/thread/1e72eb22780bfcee/6939ac83d77b8ded?q=don't-click-the-reply-link-that-is-in-plain-sight+To-get-context-the-easy-way+on-Google+zzz+show-options*-*-*-snip-*-*-*-*-the-automated-blockquote-*-*-*+click-THAT-Reply-link

RST Engineering (jw) wrote:
. . .
Then answer the question.

Did you find my answer to be inadequate or incorrect? If so, in what
ways? If not, why do you need it to be answered again?

Roy Lewallen, W7EL
-- one of the "'spice' folks"

"RST Engineering (jw)" schrieb im Newsbeitrag
...
I simulated your question in a first trial. Here is the result:
approx. 70MegHz resonance for 100pF, 30mOhm ESR and 5nH for the trace.
Surely I would prefer smd chips having better results.

But that wasn't the question. THe question was to simulate a 1000 pf (1
nf)
capacitor at 150 MHz. with an inch of lead or an inch of normal pcb trace
and tell me what you get.

Then answer the question.

OK - playing on:
I got nothing. There is no power supply. No antenna interaction. No thermal
noise source. You circuit is bull****!

Maybe we have a communication problem and should drink a beer??
- Henry

"Winfield Hill" wrote in message
...

jw\ wrote...

The question was to simulate a 1000 pf (1 nf) capacitor at
150 MHz. with an inch of lead or an inch of normal pcb trace
and tell me what you get.

Such a question is stupid and incomplete.

No, Win, the question is well formed and quite complete. Sleep off the ten
shots of Old Rammycackle and let's have the discussion when you are sober.



First of all, in
cases where impedance matters, one wouldn't dare use an inch
of lead at 150MHz, we'd cut that short, 0.1-inch max.

No, Win, neither you nor I would do such a thing. But somebody who is (as
the OP posted) new to the RF world would do so without a second thought.
You and I have been playing this game all our lives and take self-resonance
into account without even thinking about it. However, a student new to the
field (as my freshman engineering students are) makes the mistake
repeatedly, even when using a decent text called ... um ... The Art Of
Something Or Other. When their RF amplifier starts squeeging or
motorboating, I tell them that the power supply isn't bypassed well enough,
and I'll be damned if the first thing they do is put a BIGGER capacitor on
the supply line.

I'll then ask them what they think the bypass impedance is and get the stock
answer "1/(2*pi*f*c)". Hm, says I, how about the three inches of wire
between the capacitor and the supply line. Oh, says them, that's a direct
short. Straight wire doesn't have a reactive component. Hm, says I, let's
see what the network analyzer says about that. Hm, says student, it says 60
nanohenries. How can that be? Mm, 20 nanohenries per inch for #20 wire
sounds about right, so what does that series circuit look like? Hm.
Inductive at the frequency of interest. Now, grasshopper, tell me about
self-resonance of capacitors with long leads.




And
we certainly wouldn't use an inch of pcb trace unless it was
field-controlled with a ground plane.

That's not always an option in commercial gear, Win.



This is true whether a
1nF cap is involved or not. If you were to insist on analyzing
an inch of lead, we'd insist on knowing *all* about the ground
scene. Since you aggressively put your question without any
relevant information about what the ground is like, and where
it is, the question is intrinsically-stupid and incomplete.


If I didn't say what the ground is, then we can assume that I formulated the
question without ground plane. 99% of the commercial products run this way.



Sorry, jw\, but that's the way it is.

Sorry, Win, that's NOT the real world.

Jim

On Wed, 23 Nov 2005 15:05:42 -0800, "RST Engineering \(jw\)"
wrote:


"Henry Kiefer" wrote in message
...
OK Jim -

I simulated your question in a first trial. Here is the result:
approx. 70MegHz resonance for 100pF, 30mOhm ESR and 5nH for the trace.
Surely I would prefer smd chips having better results.

But that wasn't the question. THe question was to simulate a 1000 pf (1 nf)
capacitor at 150 MHz. with an inch of lead or an inch of normal pcb trace
and tell me what you get.



The question is unclear. Any component must have a return path, either
when you measure it or when you use it in a circuit. The entire loop
determines the "lead" inductance. If I solder an axial cap, with 1" of
extra leads, onto the end of a hunk of coax, and analyze it with a VNA
or TDR, I can bend the cap leads into various fat/flat loops and push
the L all over the place.

John

And why, Jim, you don't comment my effort?

Maybe I'm newer to rf as you but where is the difference between a
microprocessor decoupling from the power supply at 100MegHz and a rf stage
at the same frequency? Truly the cpu is more challenging because of the
broad used spectrum above 100MegHz.

Done PowerPC, PCI stuff and others....

- Henry

RST Engineering (jw) wrote:


"Winfield Hill" wrote in message
...

jw\ wrote...

The question was to simulate a 1000 pf (1 nf) capacitor at
150 MHz. with an inch of lead or an inch of normal pcb trace
and tell me what you get.

Such a question is stupid and incomplete.

No, Win, the question is well formed and quite complete. Sleep off the
ten shots of Old Rammycackle and let's have the discussion when you are
sober.

It is not a complete question. You could get all sorts of different
parasitic inductance values by putting the component near or far from other
metallic objects, which usually occurs to some extent in any practical
situation. Many other things will affect the answer.

You have not yet supplied anything other than a single dimension measurement
for the component. If you want the inductance, skin effect, etc. then you
would have to give me a dimensioned drawing showing the placement of the
wires, the plating material, plating thickness and the internal
construction of the capacitor. (You would also have to pay me enough to
make it worth me bothering to simulate it.) Your question is incomplete.

First of all, in
cases where impedance matters, one wouldn't dare use an inch
of lead at 150MHz, we'd cut that short, 0.1-inch max.

No, Win, neither you nor I would do such a thing. But somebody who is (as
the OP posted) new to the RF world would do so without a second thought.
You and I have been playing this game all our lives and take
self-resonance
into account without even thinking about it. However, a student new to
the field (as my freshman engineering students are) makes the mistake
repeatedly, even when using a decent text called ... um ... The Art Of
Something Or Other. When their RF amplifier starts squeeging or
motorboating, I tell them that the power supply isn't bypassed well
enough, and I'll be damned if the first thing they do is put a BIGGER
capacitor on the supply line.

I'll then ask them what they think the bypass impedance is and get the
stock
answer "1/(2*pi*f*c)". Hm, says I, how about the three inches of wire
between the capacitor and the supply line. Oh, says them, that's a direct
short. Straight wire doesn't have a reactive component. Hm, says I,
let's
see what the network analyzer says about that. Hm, says student, it says
60
nanohenries. How can that be? Mm, 20 nanohenries per inch for #20 wire
sounds about right, so what does that series circuit look like? Hm.
Inductive at the frequency of interest. Now, grasshopper, tell me about
self-resonance of capacitors with long leads.




And
we certainly wouldn't use an inch of pcb trace unless it was
field-controlled with a ground plane.

That's not always an option in commercial gear, Win.
Well as you have not specified whether this is "commercial gear" and what
type of PCB material, dielectric thickness, trace width etc. of course we
can't tell you the answer. Neither could a guy who was going to answer
your question by building one and measuring it. He could find one possible
answer but there are lots of possible answers which differ because you have
not given us a complete problem to solve.


This is true whether a
1nF cap is involved or not. If you were to insist on analyzing
an inch of lead, we'd insist on knowing *all* about the ground
scene. Since you aggressively put your question without any
relevant information about what the ground is like, and where
it is, the question is intrinsically-stupid and incomplete.


If I didn't say what the ground is, then we can assume that I formulated
the
question without ground plane. 99% of the commercial products run this
way.
You still gave insufficient information on the wire geometry. I would
refute your claim that 99% of commercial products don't use a ground plane.
The cell-phone market is in the high hundreds of millions of units this
year, and is likely to reach 1 billion units per year next year, and I
guarantee you that every one will contain a multi-layer PCB with ground
planes and microstrip traces etc. every one of them designed using field
simulators and some version of SPICE to model the integrated circuit
packages and bondwires, as well as the antenna. I don't believe that this
one billion units would fit into the 1% minority of products that you think
have ground planes!

Sorry, jw\, but that's the way it is.

Sorry, Win, that's NOT the real world.

Jim

Anyhow, until you tell me how long a piece of string is, (to the nearest
micron or micro-inch whichever you prefer), I have had enough of this
thread.

Chris

Am Thu, 24 Nov 2005 09:55:13 -0800 schrieb RST Engineering (jw)
:

into account without even thinking about it. However, a student new to
the
field (as my freshman engineering students are) makes the mistake
repeatedly, even when using a decent text called ... um ... The Art Of
Something Or Other. When their RF amplifier starts squeeging or
motorboating, I tell them that the power supply isn't bypassed well
enough,
and I'll be damned if the first thing they do is put a BIGGER capacitor
on
the supply line.

Like some of us could lough nicely, when a new guy at a customer
(semiconductor fab/asics) of the last company I worked for had to test an
RF Chip. Another engineer came to look what the guy is doing, saw he
didn't bypass the power supply and recommended to do so. The young
engineer put a nice 2200µF electrolytic at the terminals of the
lab-power-supply.



--
Martin