Ray Anderson put the information at: http://groups.yahoo.com/group/si-list/files/Technical%20Documents/ under "SMA Launch Structure Info" I always went to microstrip. I would think your S11 resonance merely = indicates a noisy launch. I wouldn't be surprised to find that the = microstrip launch would be noisier than that for coplanar - the = transition (from SMA connector environment to PCB) is more complex and = easier to induce discontinuities. Jeff Loyer -----Original Message----- From: Perry Qu [mailto:perry.qu@xxxxxxxxxxx] Sent: Tuesday, April 22, 2003 7:29 AM To: scott@xxxxxxxxxxxxx; Loyer, Jeff Cc: si-list Subject: Re: [SI-LIST] Re: [Fwd: coax to PCB transition - return loss] Scott, Jeff: Thanks for your info. It's not clear to me what type of transmission = line you used on PCB, microstrip or coplannar waveguide ? Jeff, can you send me = the slides you are talking about ? I re-examined some of our measured data for various coax-to-PCB = interface and it appears that whenever microstrip is used, I see some resonance in S11 = frequency domain plot (10 - 240 MHz). This resonance basically screw up my return = loss out of -15 dB. However, for coplannar waveguide, it appears to be a = linearly-rising curve with no resonance and it meets -15dB faily well. BTW, I need to clarify a bit about the interface: The interface I'm = talking about here is the analogue link between SMZ connector and Tranceiver = analogue side. There are a bunch of passive elements in between (transformer, = protection diode, etc.). The "ground" in microstrip or coplannar waveguide is = completely isolated from PCB digital ground. Regards Perry Scott McMorrow wrote: > Bill, > > I'm not quite sure what you are asking. An SMA by nature is a > single-ended creature. Measurements were made single-ended with one > SMA, and differentially with two SMAs. But in both cases single-ended > cables and TDR heads were used. The TDR profiles matched simulation > with extremely good accuracy, including all high frequency resonances. > > In about a month we'll see how close the optimized SMA launch pattern > matches simulation. It will no doubt be better than our first try and > will allow us to further refine our modeling and simulation = techniques. > > scott > > bpanos wrote: > > >Scott- > >Were your measurements made with a single ended line or a = differential? > > > >-Bill > > > > > > > >Scott McMorrow wrote: > > > > > > > >> Ron, > >> > >>I have a vertical (top mount) SMA design that I've simulated and > >>measured with the following characteristics: > >> > >>Insertion loss -1 dB @ 16 GHz > >>Return loss -20 dB @ 12 GHz > >> > >>With this top mount sma we see a worst case TDR profile off a Tek > >>TDS8000 17 ps head of 49 to 54 ohms. > >> > >>This design has been correlated to 3D full-wave simulation by > >>measurement in both the time and frequency domain. As a result, I = have > >>redesigned the launch to have the following characteristics. > >> > >>Insertion loss -1 dB @ 27 GHz > >>Return loss -30 dB @ 12 GHz > >>-20 dB @ 22 GHz > >> > >>with a simulated TDR profile of 50 ohms +/- 1 ohm. > >> > >>Depending upon where the signal is that needs to be tested, the = launch > >>can either be done from top or the back side of the board, which = reduces > >>the via stub problem. > >> > >>regards, > >> > >>scott > >> > >>-- > >>Scott McMorrow > >>Teraspeed Consulting Group LLC > >>2926 SE Yamhill St. > >>Portland, OR 97214 > >>(503) 239-5536 > >>http://www.teraspeed.com > >> > >>ron miller wrote: > >> > >> > >> > >>>Hi > >>> > >>>It looks like whether coplanar or coax the vertical mount is not to = be > >>>recommended. > >>> > >>>The big problem is the via,and the via capacitance, and the via = stub. > >>>This can go as low > >>>as 30 ohms. Your worst case stub is .093 mils or about 10 ps one = way or > >>>20 ps round trip and > >>>about two degrees 1/200 of error at 240 Mhz so it should probably = be ok > >>>unless you must have a very > >>>accurate timing edge in your signal. > >>> > >>>However, be sure to remove internal pads, and keep the spacing to = the > >>>antipads as large as possible. > >>> > >>>For test purposes it is better to connect a piece of semirigid .047 = or > >>>.093 OD with a female sma > >>>attached to two surface pads. > >>> > >>>Ron Miller > >>> > >>>dmitrik@xxxxxxxxxxx wrote: > >>> > >>> > >>> > >>> > >>> > >>>>-------- Original Message -------- > >>>>Subject: [SI-LIST] coax to PCB transition - return loss > >>>>Date: Wed, 16 Apr 2003 10:50:17 -0400 > >>>>From: "Perry Qu" <perry.qu@xxxxxxxxxxx> > >>>>Reply-To: perry.qu@xxxxxxxxxxx > >>>>Organization: Alcatel Canada > >>>>To: si-list <si-list@xxxxxxxxxxxxx> > >>>> > >>>> > >>>>Hi, > >>>> > >>>>I have been having problems in designing STM1 electrical interface = to > >>>>pass return loss requirement (< -15 dB up to 240MHz). We don't = have a 3D > >>>>full wave tool in house so I can't really simulate the interface = and > >>>>provide proper design guidelines. My question, what will be the = best > >>>>coax to PCB transition (75 ohm vertically-mounted SMZ connector): > >>>> > >>>>1. a microstrip, where center conductor of SMZ is connected to > >>>>microstrip lines on PCB and the 4 ground pins are connected to the > >>>>reference copper on PCB; > >>>> > >>>>2. A coplannar waveguide structure, ground - signal -ground, where > >>>>signal is connected to center conductor and ground is connected to > >>>>ground pins on SMZ. > >>>> > >>>>As long as we maintain 75 impedance control, I don't see much = difference > >>>>in terms of return loss performance for the above two. > >>>> > >>>>Also, how significant will through hole via along the signal path = affect > >>>>return loss at 240 MHz (assume 0.093" thickness) ? > >>>> > >>>>Thanks for your input. > >>>> > >>>>Regards > >>>> > >>>>Perry > >>>> > >>>>-- > >>>>Perry Qu > >>>> > >>>>SDN D & Q | 600 March Road > >>>>Alcatel Canada | Ottawa, ON K2K 2E6, Canada > >>>> > >>>>DID: (613) 7846720 | FAX: (613) 5993642 > >>>> > >>>> > >>>>------------------------------------------------------------------ > >>>>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 > >>>> > >>>> > >>>> > >>>> > >>>> > >>>> > >>> > >>> > >>> > >>-- > >>Scott McMorrow > >>Teraspeed Consulting Group LLC > >>2926 SE Yamhill St. > >>Portland, OR 97214 > >>(503) 239-5536 > >>http://www.teraspeed.com > >> > >>------------------------------------------------------------------ > >>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 > >> > >> > >> > > > > > >-- Binary/unsupported file stripped by Ecartis -- > >-- Type: text/x-vcard > >-- File: bill.panos.vcf > >-- Desc: Card for bpanos > > > > > >------------------------------------------------------------------ > >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 > > > > > > > > > > -- > Scott McMorrow > Teraspeed Consulting Group LLC > 2926 SE Yamhill St. > Portland, OR 97214 > (503) 239-5536 > http://www.teraspeed.com > > ------------------------------------------------------------------ > 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 > -- Perry Qu SDN D & Q | 600 March Road Alcatel Canada | Ottawa, ON K2K 2E6, Canada DID: (613) 7846720 | FAX: (613) 5993642 ------------------------------------------------------------------ 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