Fangyi, We had extensive discussions on this topic earlier this year when Scott expressed his concerns about the S-parameter based analog buffer models described in the various versions of the "analog modeling BIRD-s". The summary of that discussion was captured in a PPT file based on the comments and discussions of the participants of the ATM task group. The decisions we made are noted in red letters on the last slide. I wrote this presentation to document the outcome of our discussion and so that at the time when we write/edit the analog BIRD(s), we would have our decisions ready to go without having to rehash the same discussions again. The intent is to put the definitions and statements in this presentation into the IBIS specification in the area where the analog models using S-parameter models are described. Please refer to this document with your questions and discussions on this topic. I do not want to go through the same conversation again... (it was long, complicated, and at times somewhat painful). Thanks, Arpad ================================================================= From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Walter Katz Sent: Thursday, December 01, 2011 9:05 PM To: fangyi_rao@xxxxxxxxxxx; ibis-macro@xxxxxxxxxxxxx Subject: [ibis-macro] Re: Jitter BIRD issues, and Buffer Tstonefile Issues Fangyi, Why not let the EDA tool decide how to terminate it, based on the simulator being used? Walter From: fangyi_rao@xxxxxxxxxxx<mailto:fangyi_rao@xxxxxxxxxxx> [mailto:fangyi_rao@xxxxxxxxxxx]<mailto:[mailto:fangyi_rao@xxxxxxxxxxx]> Sent: Thursday, December 01, 2011 9:04 PM To: wkatz@xxxxxxxxxx<mailto:wkatz@xxxxxxxxxx>; ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx> Subject: RE: [ibis-macro] Jitter BIRD issues, and Buffer Tstonefile Issues Hi, Walter; Regarding touchstone file, the Rx E element is equivalent to terminating the Rx S-parameter block with open. Since some internal tools used by IC vendors don't assume the same termination condition, it's better to allow model developers to specify termination to avoid confusion when correlating with internal tools. Regards, Fangyi From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx> [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]<mailto:[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]> On Behalf Of Walter Katz Sent: Tuesday, November 29, 2011 2:31 PM To: IBIS-ATM Subject: [ibis-macro] Jitter BIRD issues, and Buffer Tstonefile Issues All, The remaining major issue is the handling of Rx_Rj, Rx_DCD, and Rx_Sj. 1. It has been requested that Rx_Dj be added. 2. First a discussion on how the Rx clock is handled in the following two cases a. Time Domain i. Rx AMI_GetWave returns clock ticks in *clock_times. b. Statistical i. Rx AMI_GetWave does not return clock ticks in *clock_times. ii. Using Rx AMI_Init 3. The current BIRD 123 states that Rx_Rj, Rx_DCD, and Rx_Sj shall be applied to both Time Domain and Statistical methods. a. In Time Domain, Rx_Rj, Rx_DCD, and Rx_Sj can be applied to times in clock_times, statistically to the clock_times PDF, or statistically to the persistent eye. b. In Statistical, Rx_Rj, Rx_DCD, and Rx_Sj are combined statistically along with Rx_Clock_PDF, Rx_Clock_Recovery_Rj, Rx_Clock_Recovery_DCD, and Rx_Clock_Recovery_Sj. 4. It has been suggested that Rx_Rj, Rx_DCD, and Rx_Sj shall apply to just Time Domain. a. In Time Domain, Rx_Rj, Rx_DCD, and Rx_Sj can be applied to times in clock_times, statistically to the clock_times PDF, or statistically to the persistent eye. b. In Statistical, only Rx_Clock_PDF, Rx_Clock_Recovery_Rj, Rx_Clock_Recovery_DCD, and Rx_Clock_Recovery_Sj are applied. Regarding Tstonefile. 1. Fangyi and I agreed the there is no requirement that S12=S21, and that S21 can be small or zero. 2. Fangyi and I agreed that the input to the Tx, and the output of the Rx S element be isolated with a unit gain amplifier (E element) as in the following example of a Tx Tstonefile wrapped in an ISS subckt: a. .subckt Intrinsic_Tstonefile_Tx DieP PadP DieN PadN file='NA' b. * Port order of Touchstone file is DieP PadP DieN PadN c. E_H EDieP 0 VCVS DieP 0 1. d. E_L EdieM 0 VCVS DieN 0 1. e. S1 EDieP PadP EDieN PadN 0 mname=A f. .model A TSTONEFILE=file g. .ends Intrinsic_Tstonefile_Tx 3. There are now three proposals to implement Tstonefile in .ibs and/or .ami files. a. BIRD 120 proposes the following example, where (Voh-Vol) = Peak to Peak voltage swing: i. (Tstonefile (List "xwc.s4p" "wc.s4p" "nc.s4p" "bc.s4p" "xwc.s4p") ii. (Usage Info) (Type String) iii. (Description "Extreme Worst, Worst, Nominal, Best, Extreme Best")) iv. (Vol (Value 0.) (Usage Info)(Type Float)) v. (Voh (Range 1 .3 1.2) (Usage Info)(Type Float)) b. There are a number of BIRDs submitted by Arpad and Ambrish. I have requested that the above example be implemented using the syntax proposed in these alternative BIRDs. Walter Walter Katz wkatz@xxxxxxxxxx<mailto:wkatz@xxxxxxxxxx> Phone 303.449-2308 Mobile 720.333-1107