Hi James & Jagdeep, I would like to add if the absolute delay is <1ns then the trace is has little attenuation and is relatively short for rise times in the order of 1 ns (<ns is mentioned) and therefore of moderate consequence on the load of the receiver. i would assue that you would match the line impedance to the receiver impedance with a terminating resistor. It the source is an oscillator and presumably free-running, why would you have a requirement for an absolute delay of <1ns. Have I misunderstood or could you clarify. -- Regards, __________ James G Roberts /___ ____ | jrobert@xxxxxxxxxxxxxxxxxxxxx Jim __ / /___/ / jgroberts@xxxxxxxxxx / /_/ /---| | Room: BE436, Hilversum \____/ /_/ Tel: +31 35 687 4308 Fax: 5976 "Jones, James R" wrote: > 1. You could use a rule of thumb of 180ps/inch for stripline, say 160ps for > microstrip. Keep in mind that you would need to use a 2D field solver if > you want to get a closer approximation for propagation velocity. > > 2. Yes, trace length does have an effect on rise/fall times. Let me > explain... for an infinitely long trace, the impedance looking into the > trace is equal to the characteristic impedance. For an infinitely short > trace, the impedance looking into the trace is the load of the receiver, > usually much larger than the characteristic impedance. You will be using a > trace of some finite length, so the load that the driver sees will be > somewhere in between these two extremes. As you can imagine, the amount of > driver loading will affect the rise/fall time. I recommend simulating this > if you know that you have to meet a certain rise/fall time spec. > > Hope this helps, > James R. Jones > Dell > > -----Original Message----- > From: jagdeep singh [mailto:jagsim@xxxxxxxxx] > > 2. Given the device parameters, how does trace length effect 10-90 Rise/Fall > time of a particular signal. I thot rise/fall times are a factor of only > knee freq., but does trace length has any effect on rise/fall times? > > >From an oscillator to a device, how do I make sure that the rise/fall time ------------------------------------------------------------------ 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