I thought one of the things that make X2Y capacitors lower inductance is
that the current in each terminal flows in opposite directions causing a
cancellation effect. This is from X2Y website:
- Low inductance due to cancellation effect
I used them on some boards back when they came out. I can't say they worked
better than 0402 capacitors because I did not do any detailed measurements.
You really need to consider the whole PDN system including the mounting
inductance, spreading inductance, IC package parasitics, frequency
spoectrum of IC switching current, any decoupling that might be inside the
IC package which is often an unknown. I think this detailed kind of
analysis would be nice to do but is rarely done. IME I have never had a
problem just following good design practices.
On Fri, Mar 11, 2016 at 9:50 AM, Grasso, Charles <
Charles.Grasso@xxxxxxxxxxxx> wrote:
Hello,
Current thinking has it that the PDN performance is only as good as the
first pwb resonance
(typically in the few hundreds of MHZ - I have seen 300 as a commonly used
number) and
that the BGA decoupling is (for the most part) taken care of by the
substrate capacitance.
In other words - it is my understanding that the board decouplers don't
really need to be
"high" performers are the frequencies of interest are (relatively) low.
I'd appreciate the communities thoughts on this.
[Hello Mike - Good to "see" you again!]
Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) 3032042974@xxxxxxxxx
(e) charles.grasso@xxxxxxxxxxxx
(e2) chasgrasso@xxxxxxxxx
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Michael Vrbanac
Sent: Friday, March 11, 2016 9:42 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: X2Y equivalent circuit model
I agree that Steve had this correct. I had some offline discussions
w/Steve back in that timeframe and between that and the decoupling
capacitor/PDN performance optimization research studies we did at in my EMC
design research lab at Compaq on this topic back in the early 90's, also
considering "side mounted decoupling capacitors" (yes, that format was
around back then) because we were already seeing EMC issues long before
anyone became concerned about PDN performance. Anyway, Steve and I were in
agreement that they worked well enough but that the layout and placement
were absolutely critical which agrees with Scott's recent input on this re:
spreading inductance and placement distance. If it matters, we had the test
boards micro-sectioned after the fact to make absolutely sure that we made
no assumptions about mounting dimensional parameters. IIRC, someone on that
team later wrote a paper on part of that study (not all) but I have since
forgotten its title and the name of fe
llow who wrote it. Sorry I cannot remember who but that was back in the
days when my head was handed to me daily for saying what this forum has
rightly understood these days as good engineering practice. It was heresy
back then. BTW, as you might guess, the results of that study back then
were in good agreement with most of what has been posted on here as good
design practice for quite some time. I hope that helps.
Michael E. Vrbanac
EMC Forensics, President
On 03/11/2016 10:00 AM, David Anthony wrote:
Lee, the vendors dimensionally detail land pad 'recommendations' forX2Y, but stay away from dimensioning specific via layouts. Scroll down to
Johanson's 'PCB mounting' tab at this link:
http://www.johansondielectrics.com/x2y-filter-decoupling-capacitors#pcbin the PDN Bypass applications section, notice the 'recommended' and 'poor'
Below the land pad dimensions, Johanson shows 'stick' figure via layouts
layout depictions, no dimensions. If any vendor sent you, or you downloaded
a vendor document specifying the poor layout please send it to me. Steve
would not specify that poor layout as you suggest, these early 2004-05
papers are just a few examples of the low inductance he preached:
http://www.ipblox.com/pubs/DesignConEast_2005/DesignCon%20East%202005%20TF2_ipb.pdf
Bypass Capacitor Inductance, Data Sheet Simplicity to Practical Reality
On Behalf Of Lee Ritchey
Considerations for Capacitor Selection in FPGA Designs
http://www.x2y.com/publications/decoupling/mar21-05.pdf
-Dave
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
Sent: Friday, March 11, 2016 1:07 AMCharles.Grasso@xxxxxxxxxxxx; 'Ray Anderson'
To: tom@xxxxxxxxxxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx; 'Ray Anderson'; cristian.gozzi@xxxxxxxxx;
Subject: [SI-LIST] Re: X2Y equivalent circuit modelvendor. I believe that that layout was specified by Steve. IT looks like
The board layout complied exactly with what was specified by the
what is on his test PCB.
On Behalf Of Tom Dagostino
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
Sent: Wednesday, March 9, 2016 10:19 AMcristian.gozzi@xxxxxxxxx; Charles.Grasso@xxxxxxxxxxxx; 'Ray Anderson' <
To: leeritchey@xxxxxxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx; 'Ray Anderson' <raya@xxxxxxxxxx>;
ray.anderson@xxxxxxxxxx>
Subject: [SI-LIST] Re: X2Y equivalent circuit modelwas incorrect.
Lee you know that board was not the optimal layout. Steve told you it
Tom Dagostinoleeritchey@xxxxxxxxxxxxx> wrote:
Tom Dagostino
Teraspeed LabsOn Mar 9, 2016 8:30 AM, Lee Ritchey <
03/11/16We mounted the X2Y capacitors exactly as specified in the applications------------------------------------------------------------------
notes provided by the vendor.
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Grasso, Charles
Sent: Monday, March 7, 2016 7:46 AM
To: leeritchey@xxxxxxxxxxxxx; cristian.gozzi@xxxxxxxxx; 'Ray Anderson'
<ray.anderson@xxxxxxxxxx>; si-list@xxxxxxxxxxxxx
Cc: 'Ray Anderson' <raya@xxxxxxxxxx>
Subject: [SI-LIST] Re: X2Y equivalent circuit model
Hello Lee - What method is used for a capacitor to be properly
mounted? So, if an X2Y capacitor is properly mounted the <insert
metric here> will not improve?
Best Regards
Charles Grasso
Compliance Engineer
Echostar Communications
(w) 303-706-5467
(c) 303-204-2974
(t) 3032042974@xxxxxxxxx
(e) charles.grasso@xxxxxxxxxxxx
(e2) chasgrasso@xxxxxxxxx
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Lee Ritchey
Sent: Saturday, March 05, 2016 5:44 AM
To: cristian.gozzi@xxxxxxxxx; 'Ray Anderson'; si-list@xxxxxxxxxxxxx
Cc: 'Ray Anderson'
Subject: [SI-LIST] Re: X2Y equivalent circuit model
Our tests show that the X2Y capacitor is no better than a properly
mounted
0402 capacitor.
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Cristian Gozzi
Sent: Friday, March 4, 2016 10:57 AM
To: Ray Anderson <ray.anderson@xxxxxxxxxx>; si-list@xxxxxxxxxxxxx
Cc: Ray Anderson <raya@xxxxxxxxxx>
Subject: [SI-LIST] Re: X2Y equivalent circuit model
Thanks
it worked ;-)
Regards
Cristian
Il giorno gio 3 mar 2016 alle ore 10:04 Ray Anderson <
ray.anderson@xxxxxxxxxx> ha scritto:
Cristian-attachments immediately.
Johanson Dielectrics has downloadable spice models available from
this web
page:
http://www.johansondielectrics.com/x2y-filter-decoupling-capacitors
download link:
http://www.johansondielectrics.com/downloads/JDI_X2Y_H-Spice_Files.z
ip
They should be usable in ADS using the ADS 'Hspice Compatibility
Component' Wizard. (in fact I just confirmed that they import OK).
-Ray Anderson
Xilinx Inc.
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Cristian Gozzi
Sent: Thursday, March 03, 2016 9:07 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] X2Y equivalent circuit model
Hi Si expert
I was looking for a good circuit model for X2Y capacitor to be used
in my ADS circuit simulation
on internet I found this
http://www.x2y.com/bypass/X2Y%20Equivalent%20Circuit%20for%20Models.
pd
f
but when I tried to implemented it, something was wrong The
impedance vs freq. shapes on log/log scale does not seem correct
can someone give to me any feedback or good reference to look for?
thanks in advance
Regards
Cristian
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