In my classes I often tell my students unvalidated simulations are worth the
paper they are written on. That's a bit severe, but it is based on designs I
have had to fix that were designed based only on simulations.
Lee Ritchey
Speeding Edge
P.O. Box 817
Bodega Bay, CA
94923
408-781-0253
I took the energy needed to be mad
And wrote some blues
Count Basie
Worry is like a rocking chair,
It keeps you busy, but doesn’t get you anywhere.
Ross Ritchey
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On Behalf Of
Lee Ritchey
Sent: Monday, December 23, 2019 3:18 PM
To: asparky@xxxxxxxxxxxxxxxxxxxxxxxx; djschaef42@xxxxxxxxx
Cc: 'si-list' <si-list@xxxxxxxxxxxxx>; si-list-bounce@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Surface roughness of copper
Good simulation models are build by measuring real hardware. How do you think
we get loss and er data?
Lee Ritchey
Speeding Edge
P.O. Box 817
Bodega Bay, CA
94923
408-781-0253
I took the energy needed to be mad
And wrote some blues
Count Basie
Worry is like a rocking chair,
It keeps you busy, but doesn’t get you anywhere.
Ross Ritchey
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On Behalf Of
Aubrey Sparkman
Sent: Monday, December 23, 2019 2:14 PM
To: djschaef42@xxxxxxxxx
Cc: si-list <si-list@xxxxxxxxxxxxx>; si-list-bounce@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Surface roughness of copper
Measurements or simulations? Without both (in agreement) I don’t believe
either.... someone once said that both were wrong but they may be useful.
Or something like that.
Aubrey
Sent from my iPhone
On Dec 23, 2019, at 2:32 PM, Dave Schaefer <djschaef42@xxxxxxxxx> wrote:
Simulations must be proven/calibrated by measurements to be a useful tool.
Measured results on their own provide a clear indication of product
performance.
The same cannot be said for simulations alone.
Dave
On Mon, Dec 23, 2019 at 1:56 PM Tom Dagostino <tom@xxxxxxxxxxxxxxxxx> wrote:
Measurements are a great way of calibrating simulations. And
measurements are a way of verifying simulations; they can catch
errors in simulations or their setups. For most things you need both
simulations and measurements.
Tom Dagostino
971-279-5325
tom@xxxxxxxxxxxxxxxxx
Teraspeed Labs
9999 SW Wilshire Street
Suite 102
Portland, OR 97225
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
On
Behalf Of Chuck Corley
Sent: Monday, December 23, 2019 10:11 AM
To: al@xxxxxxxxxxxxxxxxx
Cc: Lyndell.Asbenson@xxxxxxxxxxx; leeritchey@xxxxxxxxxxxxx;
maruthi934@xxxxxxxxx; shlepnev@xxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx;
si-list-bounce@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Surface roughness of copper
I think Lee was also right. My understanding was he was saying
measurements are required. I agree.
But I wouldn't choose one over the other (simulations vs. measurements).
I want both. This lets me maximize the odds the design works
correctly on the first board turn.
Lee may have had something to say we missed. I noticed he tried to
reply but it was garbled by the server.
Chuck
Chuck Corley, National Instruments
Full disclosure: My company and I design and build very high
frequency RF and microwave test and measurement equipment. Including
Network Analyzers and Spectrum Analyzers. So I could be slightly
biased towards making measurements as part of a design flow ... !
;-)
On 2019-12-23 09:23, al@xxxxxxxxxxxxxxxxx wrote:measurement
Chuck, right on! Lee, really, again? Rating simulation over
slights the concept of a high confidence concerted design flowdays
capable of achieving 1 spin signal integrity IEEE P370 rated performance
to 50GHz.
It reminds me when I was applications engineering TDR/VNA in my
early
and folks asked what is better: VNA or TDR? Is night better thandark,
what is better the Ying or the Yang; they are both parts of aflow.
balanced
Stellar signal integrity design teams can usually predict simulationhow
to measurement within 2-3ohms simulation to measurement impedance
profile,
many fab-measurement cycles do you need to achieve that? Thatsimulation
capability achieves less spins and much higher performance. The partB
if this paradigm is most/all simulation packages have issues withsomething:
meshing, memory management, loss model/material identification andon
benchmarking the tools is really important also.
Having said that we (track chair folks) recently rated the track 12
Test/Measurement DesignCon papers and there are some very good
papers
PDN analysis, jitter analysis, etc. and the quality of the papersyear
this
looks really good this year. When your management explains "thecompanies
policy" is that only 1 or 2 folks are selected to attend, and youhappy
didn't make the cut, you should explain "my policy" is that I go
every year, whether the company sponsors it or not, then go!
Ping me to discuss signal integrity, fly fishing, the conference,
etc. in the bar at the DesignCon 2020 convention center during
breaks, will be
to buy you a beer or beverage. Happy Holidays SI folks!Behalf
- Al Neves
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On
Of Chuck Corleyshlepnev@xxxxxxxxxxxxx;
Sent: Sunday, December 22, 2019 9:39 AM
To: Lyndell.Asbenson@xxxxxxxxxxx
Cc: leeritchey@xxxxxxxxxxxxx; maruthi934@xxxxxxxxx;
si-list@xxxxxxxxxxxxx; si-list-bounce@xxxxxxxxxxxxxsimulating,
Subject: [SI-LIST] Re: Surface roughness of copper
Nicely said. Still, I'll take a good measurement over a simulationday.
any
That's why we make such elegant measuring equipment.Measurements and simulations go together. You need both. When
I am amazed at your statement?
measurements are needed to verify the simulation results.compare
In the Network/Spectrum Analyzer world we call it "calibration".
Your Spectrum/Network Analyzer measurements don't have good quality
unless you calibrate the instrument to a known measurement standard.
I should have said this in my earlier post: I double-check my board
simulation work and parameters by verifying them against actual
measurements. When I'm doing board design I do simulations and then
them to an actual board that's the same or close in materials andto
stackup
what I want to do, and then use measurements from that board totune/adjust
the parameters ("calibrate") until I match up with the measurementresults.
Then I have both "checked" and "calibrated" my simulations.and
I suspect Lee's comment might be directed to when people do
simulations
don't check or calibrate their simulations against real boardmeasurements.
If that's what he means than he's right. Often people cancome
accidently
up with simulation results that don't match reality.surface roughness parameters of the copper used in PCB ?
For example they may have entered a parameter wrong for the
frequency or the board material characteristics without knowing it,
and simulate incorrect results.
Chuck
Chuck Corley, National Instruments
On 2019-12-21 17:09, Lyndell Asbenson wrote:
Lee,day. That's why we make such elegant measuring equipment.
I am amazed at your statement?
-Lyndell Lee Asbenson
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Lee Ritchey
Sent: Friday, December 20, 2019 11:34 AM
To: corley@xxxxxxxxx
Cc: maruthi934@xxxxxxxxx; shlepnev@xxxxxxxxxxxxx;
si-list@xxxxxxxxxxxxx; si-list-bounce@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Surface roughness of copper
Chuck,
Nicely said. Still, I'll take a good measurement over a simulation
any
Lee Ritchey
Speeding Edge
P.O. Box 817
Bodega Bay, CA
94923
408-781-0253
I took the energy needed to be mad
And wrote some blues
Count Basie
Worry is like a rocking chair,
It keeps you busy, but doesn't get you anywhere.
Ross Ritchey
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On
Behalf Of Chuck Corley
Sent: Friday, December 20, 2019 9:45 AM
To: leeritchey@xxxxxxxxxxxxx
Cc: maruthi934@xxxxxxxxx; shlepnev@xxxxxxxxxxxxx;
si-list@xxxxxxxxxxxxx; si-list-bounce@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Surface roughness of copper
Hi Maruthi,
What's the minimum bitrate after which I should start worrying about
the
copper
You were probably hoping for a one-word answer. But instead you
might have heard back many more words than you had wished for.
Here's what I suggest as the best answers to your question in order
of
quality:
1. Best quality results: Use a simulator and enter the values as
part of your simulations. This will also allow you to learn how big
an effect this has by modifying your simulation to include or remove
the roughness effects on different runs.
2. Use Lee's list of measurements below as a rough guideline of the
losses you could expect. Not quite as good as actually simulating
it (no offence Lee ;-) but still a good estimate of how much loss
you can expect at the frequencies Lee documented.
3. Lowest quality answer: 10 Gbit/sec. This is probably the simple
one-word answer you were hoping for. This is about the speed where
I start to worry about it. But it also depends on the trace length and
other factors, so this is not an absolute answer. This is more of a
"somewhere around 10 Gbit/sec, but it depends" kind of answer. Not
nearly as high quality of an answer as #1 or #2.
Chuck
Chuck Corley, National Instruments
On 2019-12-19 11:09, Lee Ritchey wrote:
Here is some measured data that you can use to decide whether smooth
VLP copper.
is worth the cost.
In 2013 we build a test PCB with a set of trace layers built from
Reverse treat copper ( what you get if you don't specify a finish)
and
The paper was 5-TP5 Titled High Speed Losses in various materialsare,
The test traces were 8" long (20 cm) and 4.5 mils (.11 mm) wide.
At 5 GHz (10 Gb/S) the loss was 0.2 db.
At 14 GHz (28 Gb/S) the loss was 2 db.
When you need to specify smooth copper depends on how good your
serdes
how long the path is and how good the laminate is. Some newerBehalf
serdes
toleratet38 db loss at 28 Gb/S. Takes a pretty long path to need
smooth copper with such serces.
Lee Ritchey
Speeding Edge
P.O. Box 817
Bodega Bay, CA
94923
408-781-0253
I took the energy needed to be mad
And wrote some blues
Count Basie
Worry is like a rocking chair,
It keeps you busy, but doesn't get you anywhere.
Ross Ritchey
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx>
On
Of MARUTHI PRASANNA Cwrote:
Sent: Thursday, December 19, 2019 8:18 AM
To: shlepnev@xxxxxxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Surface roughness of copper
Thank you Yuryl , I'll go through them .
On Wed, Dec 18, 2019, 8:45 PM Yuriy Shlepnev
<shlepnev@xxxxxxxxxxxxx>
Hi Maruthi,
The best way to figure it out is with a numerical experiment.
To start with, pick up a realistic roughness model that correlates
with the measurements - a number of such models for different type
of copper treatments is available in our app notes at
https://www.simberian.com/AppNotes.php Build a model of your link ;
and see the impact by turning the roughness on and off.
The impact of different signal degradation factors, including
roughness, for different data rates was a subject of the recent SIJ
webinar - see #9 at https://www.simberian.com/Webinars.php
Best regards,
Yuriy
Yuriy Shlepnev, Ph.D.
President, Simberian Inc.
www.simberian.com [1] [1 [1]] [1 [1]] Simbeor - Accurate, Productive
and Cost-Effective Electromagnetic Signal Integrity Software to
Design Predictable Interconnects!
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
On
Behalf Of MARUTHI PRASANNA C
Sent: Wednesday, December 18, 2019 2:10 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Surface roughness of copper
Hi everyone
What's the minimum bitrate after which I should start worrying about
the surface roughness parameters of the copper used in PCB ?
Does the amount of signal energy in the first harmonics , second
harmonics have any impact on this ?
I appreciate answers on this , thanks in advance .
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