Agilent's app note 1491 (5989-0553EN.pdf) illustrates the points Steve made below. (Never mind that it is written by Agilent and naturally shows that Agilent's solution is "far superior" to Tektronix' one.) - Vadim On Wed, Jun 9, 2010 at 11:49 PM, steve weir <weirsi@xxxxxxxxxx> wrote: > Be wary of specifications and marketing hype and FUD. Modern scopes are > very dependent on the signal processing: analog and especially digital. > Where one vendor claims advantage in slew rate another claims advantage > in noise floor. Overactive DSP algorithms have been seen in various > scopes that create waveform artifacts that are not real. I've gone > through considerable pain with customers whose scopes were lying to > them, where we had to set-up experiments with better behaved instruments > in order to get them to see the truth. You want to know that if you > follow good measurement practice that what your scope tells you is > faithful, and not a DSP induced fantasy. > > Claims are all find and good, but for the kind of money that you are > spending, you owe it to yourself to have each vendor come in with their > scopes and put them through paces with a clock / pulse generator that > you supply in probing configurations that you set-up as representative > of the type of work you expect to do. > > The other thing that you should take into careful account is that modern > scopes represent an investment in probes that is often similar to the > price of the scope itself. It is just as important to evaluate the > probes: How they perform, do they meet your physical access needs, how > much do replacement supplies cost for things like solder ins cost, what > probes are you already invested as anything else about the scope. > > Steve. > prasad wrote: > > Hi every one.... > > > > i am evaluating high bandwidth oscilloscopes (12GHz) from different > > vendors. I was looking the data sheets of them. One of the > > them(DSO91204A) has very good noise floor compared to others. Though > > its a good thing for me but when it comes to the jitter measurements , > > the lowest jitter that can be measured on that is dependatnt on the > > slew rate of the signal ,which is actually true(since the voltage > > noise will have a second order effect on the timing of the signal). > > But when i looked at one more vendor (SDA13Zi) the noise floor is poor > > compared to other. In which case the lowest jitter that can be > > measured (jitter measurement floor)should be higher than earlier. But > > if you look at the datasheet, they have specified a fixed value for > > this which is very less . > > My question is , if the noise floor is high in the second box how > > would the jitter measurement floor be less? > > second one is , since the timing noise(jitter) is dependatnt on slew > > rate, how a fixed value is given in datasheet? > > > > > > please help me understand. Am i missing some other factor here? > > Welcome all your suggestions and ideas... > > > > > > thanks in advance... > > prasad > > > > h > > > > On 09/06/2010, colin_warwick@xxxxxxxxxxx <colin_warwick@xxxxxxxxxxx> > wrote: > > > >> (Note: I sent this info to Hermann off-list but he suggested it might be > of > >> general interest. Send flames to me, not Hermann, if it isn't.) > >> > >> In ADS the implementation is: > >> > >> > >> "Fast" corner > >> (a) the max values are selected for all the I-V data (Pullup, Pulldown, > >> Power Clamp a Ground Clamp) and for the waveform data (Ramp, Rising > Waveform > >> and Falling Waveform), and > >> (b) the min values are selected for all R, L, C, delay and TT data. > >> > >> > >> "Slow" corner is the reverse obviously > >> (a) the min values are selected for all the I-V data (Pullup, Pulldown, > >> Power Clamp a Ground Clamp) and for the waveform data (Ramp, Rising > Waveform > >> and Falling Waveform), and > >> (b) the max values are selected for all R, L, C, delay and TT data. > >> > >> > >> > >> -- Colin > >> > >> -----Original Message----- > >> . > >> . > >> . > >> > >> Any feedback from the tool vendors how they implemented this selection ? > >> > >> Thanks and Regards > >> > >> Hermann > >> > >> EKH - EyeKnowHow > >> Hermann Ruckerbauer > >> www.EyeKnowHow.de > >> Hermann.Ruckerbauer@xxxxxxxxxxxxx > >> Veilchenstrasse 1 > >> 94554 Moos > >> Tel.: +49 (0)9938 / 902 083 > >> Mobile: +49 (0)176 / 787 787 77 > >> Fax: +49 (0)3212 / 121 9008 > >> ------------------------------------------------------------------ > >> 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 > >> > >> Old (prior to June 6, 2001) list archives are viewable at: > >> http://www.qsl.net/wb6tpu > >> > >> > >> > >> > > > > > > > -- > Steve Weir > IPBLOX, LLC > 150 N. Center St. #211 > Reno, NV 89501 > www.ipblox.com > > (775) 299-4236 Business > (866) 675-4630 Toll-free > (707) 780-1951 Fax > > > ------------------------------------------------------------------ > 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 > > 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 technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu