I did not like Chris Cheng's tone and content. However, the remedy suggested is not balanced either. Emotional responses of different people differ in sophistication. Some times, they are way off of what is generally considered calm and rational. That has been very, very rare on the SIList island. Obviously, the list need to discuss about how the administrator might try to regulate eruptions. Deleting emails from list should be the last resort. Like throwing the noise out along with the signal... Sainath -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Charles Grasso Sent: Saturday, December 01, 2001 7:07 PM To: chris.cheng@xxxxxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Buried Capacitance thread comments (The whole thing) I would like to be the first to vote Chris Cheng off the SIList island. I have NEVER taken this position before but if he cannot present his thoughts ( and obvious dislike for consutants) in a calm and rational manner then I most certainly don't want him on this list. I therefore request the administrator of this list to delete his email from the list. ------------------------------------------ Charles Grasso Ansoft Corporation -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Chris Cheng Sent: Saturday, December 01, 2001 4:46 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Buried Capacitance thread comments (The whole thing) Mike, You are being to annoy me. You are running around saying in general terms what to do in PCB design but you have yet to explain a single reason why the above 200MHz decoupling is needed by using a Zycon plane in a PCB. You are throwing in terms like split planes and switching supplies none of which has anything to do with needing a Zycon plane. The former has to be managed by the planar capacitance sandwiching the signal traces(case 1b in my previous discussion)nothing you can do with Zycon planes. In the later case, I've never heard of 200MHz noise or even less than uf decoupling caps are needed for switch regulators. You continue to hide behind other people's paper to justified your claim. Ever wonder why those authors from that company didn't jump up to defend you or attack me ? (Well, actually one of them try to subtly agree with me.) Because they know my old group in that company pioneered most of the packaging and electrical analysis in that company. Some of them started those analysis under the guidance of my old group. I designed most of the original CPU packages and did most of the electrical analysis myself. I designed every single server processor modules in that company until I left and you better believe I know what are the package resonance and electrical characteristics of the things they designed. Like I said, BTDT. I am still in very good terms with their seniors and for sure I don't want/need to pull ranks in a technical discussion. You are so proud of your experiences in designing above GHz systems. I suggest you go get an NDA and take a look at those high power high frequency CPU platform design guides. Take a look at their power distribution guideline and you will know everything I said about not needing system decoupling above 200MHz is correct and you are totally out of line. Why do I know that ? Because I managed one of the first group in that PC chip company to performance these type of power distribution analysis and electrical characterization. It will be unfair advantage to me to quote the public domain design guide on their PC platform power distribution guideline because they are using sockets. However, their highend high power processors has a much more complicated but relative low impedance power pod connector. Even under those condition, NO NEED FOR ABOVE 200MHz DECOUPLING. Your reference to needing Zycon planes for decoupling core noise above 200MHz makes as much sense as trying to sell me a super soaker because there is a fire in a building down a block. No thanks, I will take a fire truck and park next to that building and turn on the fire hose. You continue to quote the Zycon paper on justifying their use. I have already pointed out the fundamental flaw in that experiment (lack of return current path necessitate the Zycon planes). I told you I used Zycon before and I didn't see any different in real world power distribution improvement. What I didn't say was I was presented the same paper you mentioned and I specifically pointed out that flaw and the presenter has no choice BUT TO AGREE WITH WHAT I SAID. It doesn't matter how many years you have worked in this industry or how many designs you have done. Some of the engineers who worked for me are fresh out of grad school doing their first design. Yet they have learned through their work and demonstrated a better understanding in electrical design and analysis than you. -----Original Message----- From: MikonCons@xxxxxxx [mailto:MikonCons@xxxxxxx] Sent: Friday, November 30, 2001 10:07 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Buried Capacitance thread comments (The whole thing) Scott presents a good summary of a portion of the questions raised on this thread by his comment below. This guidance is probably the most important one to SI engineers. "Chris has provided some additional excellent clarifications which I am generally in agreement with. The point that he (we) make is that if you engineer your return paths from die to die, the amount of noise which you have to contain through decoupling, thin dielectrics and extraordinary EMI control techniques is reduced drastically." However, other design areas impact the overall EMC performance of a design and must be integrated with the above. These include items noted by Chris such as beneficial planar stitching and the impact of myriads of vias. Additionally, there are planar splits (both power and ground), EMI confinement of on-board switching supplies (which are now often operating at 1 MHz or above), and a number of other special considerations that each different design seems to bring up. Most of these items have been discussed previously in the SI List forum. One of the most prominent solutions to these other EMC problems is the use of excellent planar bypassing/decoupling, which has been covered in-depth by many (especially by our distinguished colleagues at Sun Microsystems; i.e., Larry, Ray, and Istvan). Local and board-wide capacitor decoupling is the mainstay for lower frequency disturbances, but is limited (by inductance from physical construction and the length of connections to the planes) to under 200 MHz. That's where the interplanar capacitance, which inherently exhibits minimal inductance, takes over. The thinner the dielectric between the planes to be decoupled, the better the decoupling. This rationale was the stimulus for my earlier comments and was meant to assure our less educated colleagues were not misled as to the "simplicity" of achieving EMC in a design. A complex, high-density design requires implementation of all the techniques at our disposal. I apologize for any interpretation that I was personally attacking Chris in my initial comments. I was stating a heated difference of opinion on a subject I helped pioneer in the area of high-speed digital design. I'm glad Chris responded in depth to Scott's initial comments, as he has a lot to offer the forum. For the record, I only accept approximately one in five consulting requests that I perceive are the most challenging/difficult. All requests for my consulting services are by word-of-mouth recommendations as I do not advertise; i.e., there are no "scare tactics" in my portfolio. I have directly designed or guided over 1000 complex PCB designs in the last 16 years of consulting for an average exceeding 20 different clients per year. My client repeat rate is >98%. In the last two years, I have not worked on an active board that did not have some portion of the circuit(s) operating in excess of 1 GBPS (most above 2 GBPS), and not one of them had under 2000 vias. I critique and guide from one to five board designs per client. (How many boards does a corporate employee see each year?) My EMC modeling, analysis, and design techniques have achieved performance on (classified) programs that is over 60 dB (yes 60) below FCC Class B levels. Hopefully, this background experience constitutes enough "real world" evidence so no one thinks I am purely academic. Good engineering to all of you. Mike Michael L. Conn Owner/Principal Consultant Mikon Consulting Cell: (408)821-9843 *** Serving Your Needs with Technical Excellence *** ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu