Hi Perry: To my understanding in order to produce an eye pattern providing comprehensive SI and timing data at the input of a receiver, it is often necessary to apply a pseudo- random bit pattern at the output of the the driver. Use of .sif file with RANDOM option provides a simple way of accomplishing this objective in XTK simulations. The XTK/TLC manual states, " By using the RANDOM option, each edge defined by the PERIOD, %HIGH and CYCLES statements uses a random bit to determine if the edge will be rising or falling The first cycle is always RISING then FALLING." It is interesting to note that the pattern produced by the .sif RANDOM feature repeats after a 2**32 cycles so that the bit pattern is pseudo-random. It should be also noted that sometimes a very large CYCLES number is desirable to achieve most accurate eye diagrams. In the example .sif file given in my previous post, the number of CYCLES was set at 200. I have also used cycles numbers exceeding several thousands but the draw back is that simulation speed is then significantly reduced. Regards, Abe -----Original Message----- From: Perry Qu [SMTP:Perry.Qu@xxxxxxxxxxx] Sent: Monday, November 18, 2002 2:09 PM To: 'si-list@xxxxxxxxxxxxx' Subject: [SI-LIST] Re: A question about XTK Thanks, Abe. What exactly is "Random" option trying to accomplish ? Does it give us the random bit pattern ? I tried the "eye diagram" option in the new XTK/Eplanner on UNIX without using SIF. The "eye" does not look as expected as what we have in HSPICE, where a user-defined PRBS excitation is used. Regards Perry Abe Riazi wrote: > Perry Qu Wrote: > > Hi, Abe: > > I'm interested to know how to do this in SIF also. Could you give a short > example showing the syntax in SIF to generate a pseudo-random bit pattern ? > I'm > interested in this mainly for pre-layout simulation in scratchpad. > > THanks > > Perry > > > > > Hi Perry: > > Here is an example .sif file utilizing the RANDOM option: > > Netname PERIOD: 10 %HIGH 50 CYCLES: 200 RANDOM OFFSET: 0.0 JTTER: 0.0 > > Using a recent Nutcracker version of XTK (on a Windows NT > platform), I have been able to select any driver of the net and then > produce an eye pattern at the input of a desired receiver. As noted in my > ea rlier post, the eye pattern can reveal information related to ringback, > jiiter, > min/max slew rates, source synchronous timing, etc. > > Best Regards, > > Abe Riazi > ServerWorks ------------------------------------------------------------------ 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