KumarThere are no standards for S-parameter data either. Would you care to define one that ensures simulation accuracy and fidelity to the original source? The problem is not with the S-parameters, it is in how you create or measure them.
Scott Scott McMorrow Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 (401) 284-1827 Business (401) 284-1840 Fax http://www.teraspeed.com Teraspeed® is the registered service mark of Teraspeed Consulting Group LLC C. Kumar wrote:
arpad:you are correct. if the pole/zero is derived form analytic/near anlytic model it would do fine.However problems will show up for reduced order models (complex structures) and data from measurements. There are no standards for it. The problem is not the pole/zero but how you derive it.--- On *Mon, 6/30/08, Muranyi, Arpad /<Arpad_Muranyi@xxxxxxxxxx>/* wrote: From: Muranyi, Arpad <Arpad_Muranyi@xxxxxxxxxx> Subject: [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled sources?) To: "IBIS Macro" <ibis-macro@xxxxxxxxxxxxx> Date: Monday, June 30, 2008, 12:26 PM This may be a mute point if the pole/zero data is derived from other than S-parameter data... From the EMD perspective, I don't think we care where the pole/zero data was derived from, we would take the pole/zero data "as is", I guess...Arpad================================================== ------------------------------------------------------------------------ *From:* C. Kumar [mailto:kumarchi@xxxxxxxxx] *Sent:* Monday, June 30, 2008 11:09 AM *To:* Muranyi, Arpad; scott@xxxxxxxxxxxxx *Cc:* IBIS Macro *Subject:* Re: [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled sources?) translating to pole/zero merely hides the inadequacy of the original data. There is no guarantee that pole/zero produced by two different vendors will give the same results. They can yieldsurprising and unacceptably different answers especially if pole/zero is used non transparently used to extrapolate theoriginal data. Even the same may produce inconsistent results based on frequency range. The fundamental problem is the s-parameter data not pole/zero derived from it. The only way this problem can be solved is if everybody applies the same algorithm for pole/zero extraction. (so even if it is incorrect everybody is equally incorrect!!) --- On *Mon, 6/30/08, Scott McMorrow /<scott@xxxxxxxxxxxxx>/* wrote: From: Scott McMorrow <scott@xxxxxxxxxxxxx> Subject: [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled sources?) To: Arpad_Muranyi@xxxxxxxxxx Cc: "IBIS Macro" <ibis-macro@xxxxxxxxxxxxx> Date: Monday, June 30, 2008, 11:41 AM Arpad I think the piece you are missing is why controlled sources and pole-zero are needed. There are several reasons: 1) currently a number of vendors have realized that s-parameter models do not always simulate well in a number of environments. Sometimes they are not implemented, and when they are, simulation is often slow, and/or problematic in numerous ways. 2) having realized this, some companies have developed tools to translate s-parameters into pole/zero approximations using various methods. These models are often corrected for passivity and run extremely fast in classical environments like HSPICE. Ansoft, Sigrity and IDEMworks, among others, can all provide excellent pole-zero models from S-parameters or the output of their tools. 3) some manufacturers are already delivering models in multiple forms: coupled ideal spice, s-parameter, and HSPICE pole-zero format. 4) implementation of the HSPICE pole-zero format requires G-element or E-element controlled sources, because these are the elements that implement pole-zero polynomials in that software. 5) There are two ways to implement coupling in classical coupled spice models, using either K-elements or controlled sources. Controlled sources are sometimes preferred for simulator performance reasons. Ansoft coupled Spice models developed by their quasi-static 3D FEM tool use controlled sources for coupling. I would restrict the use of controlled sources to only those cases where they are needed. Otherwise you get into the case where a controlled source could be arbitrarily placed in signal path, thus creating an amplified model, or a model with feedback, which then could break the LTI assumption. Scott Scott McMorrow Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 (401) 284-1827 Business (401) 284-1840 Fax http://www.teraspeed.com Teraspeed® is the registered service mark of Teraspeed Consulting Group LLCMuranyi, Arpad wrote:Walter,Let's put aside for a moment all detail questions about LTI,the format of pole/zero, and consistency. My question still stands:How are we going to guarantee that this new language willtranslate into anyone's SPICE easily if we put NEW capabilities into it (such as pole/zero and impulse response based T-line data) which were never supported in any SPICE before? I can see how limiting ourselves to LTI may help to simplify this new Interconnect-SPICE specification so that this translation may be doable (although when it comes to the controlled sources I am not that sure), but I don't see how the new T-line features could be translated easily. Do you have any thoughts on how that would be done?Thanks, Arpad===================================================================------------------------------------------------------------------------ *From:* ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] *On Behalf Of *Walter Katz *Sent:* Monday, June 30, 2008 8:37 AM *To:* kumarchi@xxxxxxxxx; bob@xxxxxxxxxxxxx *Cc:* IBIS Macro *Subject:* [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled sources?) Kumar,There is an interesting analogy between Pole-Zero vs. S element, and RLGC with Ro, Lo, Co, Go, Rs, Gd data vs. R, L, G, C table data. When ICM was developed, IBIS chose to exclude Ro, Lo, Co, Go, Rs, Gd because it was only an approximation to R, L, G, C table data. Should we be *consistent* and exclude Pole-Zero, or should we include both Pole-Zero and Ro, Lo, Co, Go, Rs, Gd data?The first question is “Do we implement Pole-Zero?”. An independent question is “What format do we choose for Pole-Zero?”. First lets resolve the first question. You said “I fail to see how IBIS 'inventing' its own form and convince vendors and users to adopt the yet another new/even improved form.”. But did we not take this path already with ICM. There were several forms of s elements and RLGC element instances but IBIS chose to invent a new one for ICM. Should we be *consistent* with the ICM approach or consistent with one of the various proprietary simulators.I believe that one needs to pick a form that can easily be translated into all EDA vendors’ simulator tools. Please remember that there are unique node and element naming rules in each simulator (case sensitive for one). Should we be *consistent* with Hspice, Verilog, VHDL, QCD, …Some notable quotes on being “*Consistent*”Consistency requires you to be as ignorant today as you were a year ago. <http://www.quotationspage.com/quote/990.html> *Bernard Berenson <http://www.quotationspage.com/quotes/Bernard_Berenson/> (1865 - 1959)* Consistency is the last refuge of the unimaginative. <http://www.quotationspage.com/quote/23578.html> *Oscar Wilde <http://www.quotationspage.com/quotes/Oscar_Wilde/> (1854 - 1900)* A foolish consistency is the hobgoblin of little minds, adored by little statesmen and philosophers and divines. <http://www.quotationspage.com/quote/26760.html> *Ralph Waldo Emerson <http://www.quotationspage.com/quotes/Ralph_Waldo_Emerson/> (1803 - 1882)*, /Self-Reliance/I would be *consistent* with “If IBIS approves a standard, the members of IBIS should the new standard." What this means to me is that the choice of including Pole-Zero elements and the format of a Pole-Zero element should be driven by the needs of the user committee, the ability of vendors to create these models, and the unanimous consent of EDA vendors to agree that they can translate these models into their simulation environment.Walter-----Original Message----- *From:* C. Kumar [mailto:kumarchi@xxxxxxxxx] *Sent:* Monday, June 30, 2008 7:25 AM *To:* bob@xxxxxxxxxxxxx; wkatz@xxxxxxxxxx *Cc:* IBIS Macro *Subject:* Re: [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled sources?)before you go on to pole/zero approximation you should have an 'S' elements which directly provides the original s-parameter data either in time domain or freq domain. all the others like pole/zero are approximations, except in the case of circuit elements with analytic forms. You can add to your list controlled sources with data provided multi dimensional tables; controlled elements with hysterisis; a generic expression controlled source of the form f(v,i, parameters)=0 and so on and so forth. It is possible to reduce the controlled sources to a finite set (order of 10;s) however I am still with Arpad on this one here, unless I am not seeing something fundamental . These elements have been already implemented in equivalent forms in various flavors of spice and yes AMS and -A flavors. I fail to see how IBIS 'inventing' its own form and convince vendors and users to adopt the yet another new/even improved form. --- On *Mon, 6/30/08, Walter Katz /<wkatz@xxxxxxxxxx>/* wrote: From: Walter Katz <wkatz@xxxxxxxxxx> Subject: [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled sources?) To: bob@xxxxxxxxxxxxx Cc: "IBIS Macro" <ibis-macro@xxxxxxxxxxxxx> Date: Monday, June 30, 2008, 12:54 AM Bob,Thanks for digging this up on the use of controlled voltage source for the Laplace and Pole-Zero form of transfer functions.Is the following a correct summary:* A Touchstone file is a matrix of "Transfer Functions", where the "Transfer Function" is represented as a "Vector" of complex coefficients. o Each element of the "Vector" is the amplitude of the "Transfer Function" at a specific frequency. * Each of the "Transfer Functions" can be translated to Laplace form with a numerator and denominator polynomial. o Hspice implements the Laplace form using the E and G LAPLACE controlled voltage source. * The numerator and denominator Laplace polynomials can be factored, the numerator polynomial factored into a list of zeros, and the denominator factored into a list of poles. o Hspice implements the Pole-Zero form using the E and G POLE controlled voltage source. * Alternatively, each of "Transfer Functions" can be translated into "Impulse Responses"If this is correct, then Lossy RLGC, Touchstone, Laplace, Pole-Zero interconnect blocks can simply be represented as an EMD "Block" of the form:EMD_Block_xxxx <list of nodes> len=<length> type=<type> file=<file> * Where o EMD_Block_xxxx * Instance Designator o <list of nodes> * List of nodes o <length> * Length of interconnect in meters (applies only to RLGC) o <type> * RLGC * Touchstone * Laplace * Pole * Impulse o <file> * RLGC * Contains RLGC table data * Touchstone * sNp * Laplace * Contains Laplace polynomial coefficients * Format needs specification * Pole * Contains Pole Zero data * Format needs specification * Impulse * Contains Impulse Response data * Format needs specificationIt is a trivial exercise to convert any one of these "Types" of EMD_Blocks to Hspice W, S, E and G elements.If all of the above is correct, then there is no need for EMD_Blocks that are specifically voltage controlled sources.To answer your question: An EMD models for a group of interconnect pins is essentially an ICM [Nodal Path Description] where each of the N_sections is essentially an EMD_Block. The [Nodal Path Description] becomes a subckt with nodes consisting of external EMD pins and IBIS component pins. In ICM all of the N_section can either be all RLGC or all Touchstone. In EMD the EMD_Blocks can be any combination of RLGC, Touchstone, Laplace, Pole, Impulse, Resistor, Capacitor, Inductor, Conductance or K (coupling) elements.Walter-----Original Message----- From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]On Behalf Of Bob Ross Sent: Sunday, June 29, 2008 10:53 PM To: wkatz@xxxxxxxxxx Cc: IBIS Macro Subject: [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled sources?)Walter:Here are some responses to your questions1. HSPICE and some other SPICEs implement the Laplace and pole-zero elements as a network function WITHIN controlled sources including the VCVS (E) and VCCS (G) elements. The documention is hard to find, but the HSPICE syntax is in the HSPICE Applications Manual:Exxx n+ n- LAPLACE in+ in- k0 k1 ... kn / b0 b1 ... bm Gxxx n+ n- LAPLACE in+ in- k0 k1 ... kn / b0 b1 ... bmExxx n+ n- POLE in+ in- a {cmpl zeros) / b (cmpl poles} Gxxx n+ n- POLE in+ in- a {cmpl zeros) / b (cmpl poles}2. I think of a pole-zero block, not as the single Laplace transfer element, but as an n-port block such as proposed in some private Touchstone-like formats and possibly implemented internally and automatically from n-port table data.My question:When you say interconnect block modules of Resistor/Inductor/ Capacitor, do you really mean a low-level SPICE or SPICE-like syntax within "SPICE" subcircuits for interconnect structures?That is where K and controlled sources are valuable for many reasons. While we have not really discussed this, I have beenassuming that we need such low-levelcapability for EMD. We could formally add a basic SPICE-syntax subcircuit to the list below as one of the modules with its internal SPICE-like netlist used for connecting the R/L/C/K/E/F/G/H ... elements.BobWalter Katz wrote: > All, > > > > Based on the following assumptions for an EMD: > > > > * A module as a netlist of IBIS components and external pins > * Interconnect models between these IBIS component pins consist of a > netlist of interconnect blocks > * Interconnect block models are: > o Resistors > o Inductors > o Capacitors > o Distributed RLGC models > o S parameter Models > o Impulse Response Models > o Pole-Zero Models > >>> The purpose of this e-mail is to raise the issue of what is a Pole-Zero > model and why do we need voltage controlled sources. > > > > I refer to http://www.ece.uci.edu/docs/hspice/hspice_2001_2-217.html > > > > > Understanding Pole/Zero Analysis > > In pole/zero analysis, a network is described by its network transfer > function which, for any linear time-invariant network, can be written in > the general form: > > > > In the factorized form, the general function is: > > > > It seems to me that a Pole-Zero model can either be represented as a set > of numbers like the polynomial coefficients a0, b0, a1, b1, a2, b2, .. > or the factorized form a0, b0, z1, p1, z2, p2, ? > > Where is the controlled voltage source? > > I assume that one can model the pole-zero form into Spice, Verilog, and > VHDL primitives, and doing so might utilize controlled voltage sources > and other simulator specific models. > > Why it is not sufficient to just have a Pole-Zero model (either with > polynomial coefficients and/or pole-zero coefficients). > > Walter >-- Bob Ross Teraspeed Consulting Group LLC Teraspeed Labs 121 North River Drive 13610 SW Harness Lane Narragansett, RI 02882 Beaverton, OR 97008 401-284-1827 503-430-1065 http://www.teraspeed.com 503-246-8048 Direct bob@xxxxxxxxxxxxxTeraspeed is a registered service mark of Teraspeed Consulting Group LLC--------------------------------------------------------------------- IBIS Macro website : http://www.eda.org/pub/ibis/macromodel_wip/IBIS Macro reflector: //www.freelists.org/list/ibis-macroTo unsubscribe send an email: To: ibis-macro-request@xxxxxxxxxxxxx Subject: unsubscribe--------------------------------------------------------------------- IBIS Macro website : http://www.eda.org/pub/ibis/macromodel_wip/ IBIS Macro reflector: //www.freelists.org/list/ibis-macro To unsubscribe send an email: To: ibis-macro-request@xxxxxxxxxxxxx Subject: unsubscribe