Can't do T-LINE?

( I am reposting this question in hopes of a more helpful response )

Hi All,

Concerning [Path Description] section in Ver 3.x of .ibs...

The 'len' parameter is given in 'units' which is 'arbitrary' (i.e. not
meters) such that a distributed T-LINE model cannot be built with the
proper physical length.

** I DO NOT WANT TO BUILD A LUMPED MODEL, I WANT TO BUILD A T-LINE MODEL
**

Is this an oversight or am I not understanding the parameters?

Best Regards,

Chris Rokusek
Viewlogic Systems

     
     
|=============================================================================
| Keyword: [Path Description]
| Required: Yes
| Description: This keyword allows the user to describe the connection
| between the user accessible pins of a part and the pins
of the
| ICs mounted on that part. Each pin to node connection
is
| divided into one or more cascaded "sections", where each
| section is described in terms of it's L/R/C per unit
length.
| The Fork and Endfork subparameters allow the path to
branch to
| multiple nodes, or another pin. A path description is
| required for each pin whose signal name is not "GND",
"POWER"
| or "NC".
|
| Board Description and IC Boundaries:
|
| In any system, each part interfaces with another part at
some
| boundary. Every part model must contain the components
| necessary to represent the behavior of the part being
modeled
| within its boundaries. The boundary definition depends
upon
| the parts being represented by the model.
|
| For CARD EDGE CONNECTIONS such as a SIMM or a PC
Daughter
| Card plugged into a SIMM Socket or Edge Connector, the
| boundary should be at the end of the board card edge
pads as
| they emerge from the connector.
|
| For any THROUGH-HOLE MOUNTED PART, the boundary will be
at the
| surface of the board on which the part is mounted.
|
| SURFACE MOUNTED PART models end at the outboard end of
their
| recommended surface mount pads.
|
| If the board level component contains an UNMATED
CONNECTOR,
| the unmated connector will be described in a separate
file,
| with its boundaries being as described above for the
| through-hole or surface mounted part.
|
| Sub-Params: Len, L, R, C, Fork, Endfork, Pin, Node
| Usage Rules: Each individual connection path (user pin to node(s))
| description begins with the [Path Description] keyword
and a
| path name, followed by the subparameters used to
describe the
| path topology and the electrical characteristics of each
| section of the path. The path name must not exceed 40
| characters, blanks are not allowed, and each occurrence
of the
| [Path Description] keyword must be followed by a unique
path
| name. Every signal pin (pins other than POWER, GND or
NC)
| must appear in one and only one path description per
[Begin
| Board Description]/[End Board Description] pair. Pin
names do
| not have to appear in the same order as listed in the
[Pin
| List] table. The individual subparameters are broken up
into
| those that describe the electrical properties of a
section,
| and those that describe the topology of a path.
|
| Section Description Subparameters:
|
| The Len, L, R, and C subparameters specify the length,
the
| series inductance and resistance and the capacitance to
ground
| of each section in a path description.
|
| Len The physical length of a section. Lengths are
given
| in terms of arbitrary 'units'. Any non-zero
length
| requires that the parameters that follow must be
| interpreted as distributed elements by the
simulator.
| L The series inductance of a section, in terms of
| 'inductance/unit length'. For example, if the
total
| inductance of a section is 3.0 nH and the length
of
| the section is 2 'units', the inductance would
be
| listed as L = 1.5 nH (i.e. 3.0 / 2).
| C The capacitance to ground of a section, in terms
of
| capacitance per unit length.
| R The series DC (ohmic) resistance of a section,
in
| terms of ohms per unit length.
|
| Topology Description Subparameters:
|
| The Fork and Endfork subparameters denote branches from
the
| main pin-to-node or pin-to-pin connection path. The
Node
| subparameter is used to reference the pin of a component
or
| board as defined in a .ibs or .ebd file. The Pin
subparameter
| is used to indicate the point at which a path connects
to a
| user visible pin.
|
| Fork This subparameter indicates that the sections
| following (up to the Endfork subparameter) are
part
| of a branch off of the main connection path.
This
| subparameter has no arguments.
| Endfork This subparameter indicates the end point of a
branch.
| For every Fork subparameter there must be a
| corresponding Endfork subparameter. As with the
Fork
| subparameter, the Endfork subparameter has no
| arguments.
| Node reference_designator.pin
| This subparameter is used when the connection
path
| connects to a pin of another, externally defined
part.
| The arguments of the Node subparameter indicate
the
| pin and reference designator of the external
| component. The pin and reference designator
portions
| of the argument are separated by a period
("."). The
| reference designator is mapped to an external
| component description (another .ebd file or .ibs
file)
| by the [Reference Designator Map] Keyword. Note
that
| a Node MUST reference a model of a passive or
active
| component. A Node is not an arbitrary
connection
| point between two elements or paths.
| Pin This subparameter is used to mark the point at
which
| a path description connects to a user accessible
pin.
| Every path description must contain at least one
| occurrence of the Pin subparameter. It may also
| contain the reserved word NC. The value of the
Pin
| subparameter must be one of the pin names listed
in
| the [Pin List] section.
|
| Using The Subparameters to Describe Paths:
|
| A section description begins with the Len subparameter
and
| ends with the slash (/) character. The value of the
Len, L,
| R, and C subparameters and the subparameter itself are
| separated by an equals sign (=); whitespace around the
equals
| sign is optional. The Fork, Endfork, Node and Pin
| subparameters are placed between section descriptions
(i.e.,
| between the concluding slash of one section and the
'Len'
| parameters that starts another). The arguments of the
Pin and
| Node subparameter are separated by white space.
|
| Specifying a Len or L/R/C value of zero is allowed. If
| Len = 0 is specified, then the L/R/C values are the
total for
| that section. If a non-zero length is specified, then
the
| total L/R/C for a section is calculated by multiplying
the
| value of the Len subparameter by the value of the L, R,
or C
| subparameter. However, as noted below, if a non-zero
length
| is specified, that section MUST be interpreted as
distributed
| elements.
|
| Legal Subparameter Combinations for Section
Descriptions:
|
| A) Len, and one or more of the L, R and C
subparameters. If
| the Len subparameter is given as zero, then the L/R/C
| subparameters represent lumped elements. If the Len
| subparameter is non-zero, then the L/R/C subparameters
| represent distributed elements and both L and C must be
| specified, R is optional.
|
| B) The first subparameter following the [Path
Description]
| keyword must be 'Pin', followed by one or more section
| descriptions. The path description can terminate in a
Node,
| another pin or the reserved word, NC.
|
| Dealing With Series Elements:
|
| A discrete series R or L component can be included in a
path
| description by defining a section with L=0 and the
proper R or
| L value. A discrete series component can also be
included in
| a path description by writing two back to back node
statements
| that reference the same component (see the example
below).
| Note that both ends of a discrete, two terminal
component MUST
| be contained in a single [Path Description]. Connecting
two
| separate [Path Description] with a series component is
not
| allowed.
|-----------------------------------------------------------------------------
|
| An Example Path For a SIMM Module:
|
[Path Description] CAS_2
Pin J25
Len = 0.5 L=8.35n C=3.34p R=0.01 /
Node u21.15
Len = 0.5 L=8.35n C=3.34p R=0.01 /
Node u22.15
Len = 0.5 L=8.35n C=3.34p R=0.01 /
Node u23.15
|
| A Description Using The Fork and Endfork Subparameters:
|
[Path Description] PassThru1
Pin B5
Len = 0 L=2.0n /
Len = 2.1 L=6.0n C=2.0p /
 Fork
 Len = 1.0 L = 1.0n C= 2.0p /
 Node u23.15
 Endfork
Len = 1.0 L = 6.0n C=2.0p /
Pin A5
|
| A Description Including a Discrete Series Element:
|
[Path Description] sig1
Pin B27
Len = 0 L=1.6n /
Len = 1.5 L=6.0n C=2.0p /
Node R2.1
Node R2.2
Len = 0.25 L=6.0n C=2.0p /
Node U25.6
|
|=============================================================================
Received on Tue May 19 18:04:55 1998