[ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled sources?)
- From: "Walter Katz" <wkatz@xxxxxxxxxx>
- To: <scott@xxxxxxxxxxxxx>
- Date: Mon, 30 Jun 2008 11:29:22 -0400
Scott,
My EMD proposal includes a concept of ?Views?. One view might be as simple
as a lumped RLC, other views would include distributed RLGC (lossy and
lossless), as well as S-parameter and Pole-Zero. Each view would contain
information about the nature of the model and its bandwidth. I would not
exclude the ability to include proprietary models as well, as long as
comparably accurate non-proprietary models were included as well.
Walter
-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]On Behalf Of Scott McMorrow
Sent: Monday, June 30, 2008 11:08 AM
To: kumarchi@xxxxxxxxx
Cc: bob@xxxxxxxxxxxxx; wkatz@xxxxxxxxxx; IBIS Macro
Subject: [ibis-macro] Re: [!! SPAM] Re: EMD Pole-Zero Models (Why voltage
controled sources?)
What IBIS would provide is the encapsulation and mapping to
device/board/connector/cable pins in an EDA environment. For example,
several connector companies provide models of their connectors in the
following form:
uncoupled spice
lossless coupled spice
S-parameter
Pole-zero
All of these could be provided as options in an EMD model, with the correct
pin mapping.
There is currently no IBIS model type available for boards with components,
coupled and lossy interconnect.
There is currently no IBIS model type available that can describe an
actively equalized cable assembly.
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:
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>
<mailto:wkatz@xxxxxxxxxx> wrote:
From: Walter Katz <wkatz@xxxxxxxxxx> <mailto:wkatz@xxxxxxxxxx>
Subject: [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled
sources?)
To: bob@xxxxxxxxxxxxx <mailto:bob@xxxxxxxxxxxxx>
Cc: "IBIS Macro" <ibis-macro@xxxxxxxxxxxxx>
<mailto: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 specification
It 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>
[ mailto:ibis-macro-bounce@xxxxxxxxxxxxx]On Behalf Of Bob Ross
Sent: Sunday, June 29, 2008 10:53 PM
To: wkatz@xxxxxxxxxx <mailto:wkatz@xxxxxxxxxx>
Cc: IBIS Macro
Subject: [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled
sources?)
Walter:
Here are some responses to your questions
1. 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 ... bm
Exxx 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 been
assuming that we need such low-level capability 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.
Bob
Walter 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@xxxxxxxxxxxxx <mailto:bob@xxxxxxxxxxxxx>
Teraspeed is a registered service mark of Teraspeed Consulting Group LLC
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