Oops! Posted the signs wrong for the single termination case after bouncing off the driver. Corrected table: Z Line One Term Two Term 80% +11.1% +1.2% 85% +8.1% +0.7% 90% +5.3% +0.2% 95% +2.6% +0.1% 98% +1.0% +0.0% 102% -1.0% +0.0% 105% -2.4% +0.1% 110% -5.8% +0.2% 115% -7.0% +0.5% 120% -9.1% +0.8% Steve steve weir wrote: > Richard, VSWR causes ISI ( as does frequency dependent loss ): Signal > energy reflects first off the receiver back up the line to the > transmitter where it distorts currently transmitted data. Since the > distortion depends on prior data patterns it manifest as ISI. A simple > chart for line impedances: > > Reflected amplitude: ( Zline - Zload ) / ( Zline + Zload ) > One term pessimistically assumes 0 Ohm driver > Z Line One term Two term > 80% -11.1% +1.2% > 85% -8.1% +0.7% > 90% -5.3% +0.2% > 95% -2.6% +0.1% > 98% -1.0% +0.0% > 102% +1.0% +0.0% > 105% +2.4% +0.1% > 110% +5.8% +0.2% > 115% +7.0% +0.5% > 120% +9.1% +0.8% > > In older signaling topologies with just one termination, tightening up > tolerances buys ISI margin. In double terminated topologies there is > little to gain ISI wise with matches better than 15%. This has some > nice implications: > > 1. We can get away with skinnier traces and thinner dielectrics without > worrying too much about etch tolerance for Z control, and > 2. We also don't need to be concerned about placing etch across prepreg > from return planes for Z control. That makes putting the top power > cavity on layers 2/3, and the bottom one on N-1/N-2 where they perform > best and reduce the number of bypass caps needed a no-brainer. With > older singly-terminated signaling schemes there was an argument for > putting signal on one side of a core and plane on the other for low-cost > Z control. Typically that put Gnd on layer 2, signals on layers 3 and > 4, and the first power cavity down on layers 5/6, which really hurts Z > axis inductance for both bypass caps and the ICs. It is also > incompatible with thin core dielectrics for power delivery. > > If you are making a piece of measurement equipment then depending on > what you want to see the extra precision may be justified. > > Best Regards, > > > > Steve. > > Richard Jungert wrote: > >> Steve. >> >> Its not about ISI, ( intersymbol interference) as I recall. Its all >> about test equipment, accuracy and precision results in smaller >> reflections and better VSWR within the bandwidth of interest.. Good >> quality test equipment is all about precision, but precision costs >> money as we all know. We were making a tester box that connected to >> multi channel wide bandwidth cable ( single ended 50 ohms ) and tested >> with 35ps risetime signaling from Tek equipment. It worked but was >> expensive to make. >> >> Richard Jungert >> >> >> >> >> >>> Date: Sat, 6 Sep 2008 14:44:39 -0700 >>> From: weirsi@xxxxxxxxxx >>> To: r_jungert@xxxxxxxxxxx >>> CC: wftinghi@xxxxxxxxxxxxxx; bdempsey85@xxxxxxxxx; >>> >> costel_t@xxxxxxxxx; si-list@xxxxxxxxxxxxx >> >>> Subject: Re: [SI-LIST] Re: NELCO N-13ep HiTg > 170C >>> >>> We're not in Kansas anymore. ( Well Eric is but that's only because he >>> likes watching cows spin in tornadoes. ) The days of TTL/CMOS signaling >>> with one end terminated at speed are long gone. So, why the drive for >>> such tight Z control as +/-5%? The difference in ISI energy at the >>> receiver between a +/-10% match and a +/-5% match for both ends >>> terminated signaling standards is less than 1%. Why throw any time or >>> money at such a small improvement? >>> >>> Steve >>> >>> Richard Jungert wrote: >>> >>>> Steve. >>>> >>>> Yes, +/- 5% is higher, how much depends on your fab house. I would >>>> >> have to shop around if we needed lower cost. At the time 3 years ago I >> was building test equipment and yes the board was expensive. The >> application we were working on demanded tight impedance control. >> >>>> BTW. >>>> >>>> This guy.. >>>> Vince BeusanMEI Inc(949)460-9500www.mei4pcbs.comTells me in a >>>> >> recent email that his fab shop can do +/-5% all day long no problem >> but I have not worked with them in the past. Maybe these guys have an >> updated fab process set up where they can do tighter tolerance at >> lower cost. Only way to find out is to try it. >> >>>> Richard >>>> >>>> >>>> >>>> >>>> >>>>> From: wftinghi@xxxxxxxxxxxxxx >>>>> To: r_jungert@xxxxxxxxxxx; bdempsey85@xxxxxxxxx; >>>>> >> costel_t@xxxxxxxxx; si-list@xxxxxxxxxxxxx >> >>>>> Subject: RE: [SI-LIST] Re: NELCO N-13ep HiTg > 170C >>>>> Date: Sat, 6 Sep 2008 10:22:01 +0800 >>>>> >>>>> Richard, >>>>> >>>>> So how about the cost? I feel +/-5% tolerance impedance control will >>>>> increase the PCB cost a lot. >>>>> The most local FAB houses I worked with will increase the cost if >>>>> >> we are >> >>>>> trying to specify tolerance less than 10% due to their worse >>>>> >> yield rate. >> >>>>> Specifying 5% tolerance can easily double the cost according to their >>>>> feedbacks. >>>>> >>>>> Steve >>>>> >>>>> -----Original Message----- >>>>> From: si-list-bounce@xxxxxxxxxxxxx >>>>> >> [mailto:si-list-bounce@xxxxxxxxxxxxx] On >> >>>>> Behalf Of Richard Jungert >>>>> Sent: Saturday, September 06, 2008 5:12 AM >>>>> To: Bill Dempsey; costel_t@xxxxxxxxx; si-list@xxxxxxxxxxxxx >>>>> Subject: [SI-LIST] Re: NELCO N-13ep HiTg > 170C >>>>> >>>>> I promote Data Circuits Systems/Merix because they can spec 50 >>>>> >> ohms +/- 5% >> >>>>> tolerance which in my experience is rare in the high speed pcb >>>>> >> fab business. >> >>>>> Or at least it was 3 years ago.. Tektronix also uses this material in >>>>> building fast TDR test equipment last I heard. >>>>> >>>>> Richard >>>>> >>>>> >>>>> >>>>> >>>>> >>>>>> From: bdempsey85@xxxxxxxxx >>>>>> To: r_jungert@xxxxxxxxxxx; costel_t@xxxxxxxxx; si-list@xxxxxxxxxxxxx >>>>>> Subject: RE: [SI-LIST] Re: NELCO N-13ep HiTg > 170C >>>>>> Date: Fri, 5 Sep 2008 16:02:59 -0500 >>>>>> >>>>>> 13EP is available as 13EP-SI as well and is used for higher temp >>>>>> >>>>>> >>>>> processing >>>>> >>>>> >>>>>> used in lead-free assembly. >>>>>> *Most* customers I deal with are moving over to EP and EP-SI for >>>>>> >> RoHS >> >>>>>> products. Something to consider. >>>>>> >>>>>> -----Original Message----- >>>>>> From: si-list-bounce@xxxxxxxxxxxxx >>>>>> >> [mailto:si-list-bounce@xxxxxxxxxxxxx] >> >>>>> On >>>>> >>>>> >>>>>> Behalf Of Richard Jungert >>>>>> Sent: Friday, September 05, 2008 3:58 PM >>>>>> To: costel; si-list@xxxxxxxxxxxxx >>>>>> Subject: [SI-LIST] Re: NELCO N-13ep HiTg > 170C >>>>>> >>>>>> Costel. >>>>>> >>>>>> I would talk to the engineers at Data Circuits in San Jose about >>>>>> >> this >> >>>>>> material. Merix recently bought them out but in the old days it >>>>>> >> was Data >> >>>>>> Circuits Systems Inc who built equipment with this type of material. >>>>>> >>>>>> Have you considered Nelco N4000-13SI ? This is also a very high >>>>>> >>>>>> >>>>> performance >>>>> >>>>> >>>>>> material and in my recent designs/projects have found this >>>>>> >> material works >> >>>>>> clear up to 15Ghz bandwidth. >>>>>> >>>>>> I recommend calling the FAB house your working with. These folks >>>>>> >> have that >> >>>>>> info readily available. >>>>>> >>>>>> Richard Jungert >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>>> Date: Fri, 5 Sep 2008 03:31:05 -0700 >>>>>>> From: costel_t@xxxxxxxxx >>>>>>> Subject: [SI-LIST] NELCO N-13ep HiTg > 170C >>>>>>> To: si-list@xxxxxxxxxxxxx >>>>>>> >>>>>>> Can anybody tell me the prepreg thicknesses for NELCO N4000-13EP >>>>>>> much apreciated >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> ------------------------------------------------------------------ >>>>>>> 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 technical documents are available at: >>>>>>> http://www.si-list.net >>>>>>> >>>>>>> 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 >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>> _________________________________________________________________ >>>>>> See how Windows Mobile brings your life together-at home, work, >>>>>> >> or on the >> >>>>>> go. >>>>>> http://clk.atdmt.com/MRT/go/msnnkwxp1020093182mrt/direct/01/ >>>>>> ------------------------------------------------------------------ >>>>>> 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 technical documents are available at: >>>>>> http://www.si-list.net >>>>>> >>>>>> 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 >>>>>> >>>>>> >>>>>> >>>>>> >>>>> _________________________________________________________________ >>>>> Want to do more with Windows Live? Learn ?0 hidden secrets?from >>>>> >> Jamie. >> >> http://windowslive.com/connect/post/jamiethomson.spaces.live.com-Blog-cns!55 >> >>>>> 0F681DAD532637!5295.entry?ocid=TXT_TAGLM_WL_domore_092008 >>>>> ------------------------------------------------------------------ >>>>> 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 technical documents are available at: >>>>> http://www.si-list.net >>>>> >>>>> 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 >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>> _________________________________________________________________ >>>> See how Windows Mobile brings your life together—at home, work, or >>>> >> on the go. >> >>>> http://clk.atdmt.com/MRT/go/msnnkwxp1020093182mrt/direct/01/ >>>> ------------------------------------------------------------------ >>>> 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 technical documents are available at: >>>> http://www.si-list.net >>>> >>>> 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 >>>> >>>> >>>> >>>> >>>> >>> -- >>> Steve Weir >>> Teraspeed Consulting Group LLC >>> 121 North River Drive >>> Narragansett, RI 02882 >>> >>> California office >>> (866) 675-4630 Business >>> (707) 780-1951 Fax >>> >>> Main office >>> (401) 284-1827 Business >>> (401) 284-1840 Fax >>> >>> Oregon office >>> (503) 430-1065 Business >>> (503) 430-1285 Fax >>> >>> http://www.teraspeed.com >>> This e-mail contains proprietary and confidential intellectual >>> >> property of Teraspeed Consulting Group LLC >> >> ------------------------------------------------------------------------------------------------------ >> >>> Teraspeed(R) is the registered service mark of Teraspeed Consulting >>> >> Group LLC >> >> ------------------------------------------------------------------------ >> See how Windows Mobile brings your life together—at home, work, or on >> the go. See Now >> <http://clk.atdmt.com/MRT/go/msnnkwxp1020093182mrt/direct/01/> >> > > > -- Steve Weir Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 California office (866) 675-4630 Business (707) 780-1951 Fax Main office (401) 284-1827 Business (401) 284-1840 Fax Oregon office (503) 430-1065 Business (503) 430-1285 Fax http://www.teraspeed.com This e-mail contains proprietary and confidential intellectual property of Teraspeed Consulting Group LLC ------------------------------------------------------------------------------------------------------ Teraspeed(R) is the registered service mark of Teraspeed Consulting Group LLC ------------------------------------------------------------------ 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 technical documents are available at: http://www.si-list.net 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