AppNote 10710
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Setting Up Libraries for ELDO® Simulation with HyperLynx® Analog
By: Bill Bell Last Modified: May 13, 2009 Table of contents
Table of contents________________________________________________________________ 1 Introduction ____________________________________________________________________ 1 Terms and Definitions ____________________________________________________________ 2 Library Data Organization _________________________________________________________ 2 Property and Simulation Attribute Categories __________________________________________ 3 DxDesigner Symbol Properties Directly Used by HyperLynx Analog ________________________ 4 Common ELDO Simulation Attributes ________________________________________________ 6 Element Type Specific Property Information ___________________________________________ 8 Subcircuit Instances (Macromodels) ________________________________________________ 15 Conclusion ___________________________________________________________________ 16 Appendix - Considerations for Defining Properties for Use in Simulation ____________________ 17
Introduction This document describes how to set up libraries for simulation with HyperLynx Analog. It describes the requirements for integrating schematic design information with simulation, and also explains optional information that may be used for more advanced analyses. HyperLynx Analog provides a great deal of flexibility for defining the simulation information, so in many cases there may be more than one way to set up the library elements. This document describes the options, and outlines the considerations in choosing one option over another. This document addresses the property information relevant to the Eldo simulation engine. The information for the HyperLynx Analog Simulation Engine is comparable, but differs in the details. The information in this document is applicable to HyperLynx Analog and DxDesigner® through the EE2007.5 and PADS® 9.0 releases. Future releases may change the requirements for setting up the libraries as HyperLynx Analog evolves.
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Page 1 of 18 Copyright © 2009 Mentor Graphics Corporation
Trademarks that appear in Mentor Graphics product publications that are not owned by Mentor Graphics are trademarks of their respective owners.
Terms and Definitions The following definitions provide help in understanding key terms used in this document. It is important to understand these terms and the distinctions between them in order to understand how the information is defined, and how it is passed through to simulation. Term
Definition
Simulation Attributes
These are attributes attached to simulation element instances. They represent the information in the simulation netlist, after it has been derived from the Properties. There may or may not be a one-to-one correspondence of properties to simulation attributes. For a more detailed description of this, please see the Property and Simulation Attribute Categories section and the Appendix - Considerations for Defining Properties for Use in Simulation.
Properties
These are the properties as attached to the schematic symbols. This represents the information that is placed on the design by the user (either explicitly or as part of placing the symbol). Some properties are used by simulation, others are not (for example, they may be used for PCB layout). The properties that are used by simulation will likely map to one or more simulation attributes as discussed below.
Library Data Organization HyperLynx Analog uses properties on the symbols in a schematic design for assigning simulation information to individual schematic elements. These properties may be populated in several different ways: •
On the symbol definition directly
•
From a PDB entry when using “Place by Part”
•
From a DxDataBook™ entry when using DxDataBook
•
On the individual symbol instance in the schematic
The choice of where to place the simulation information depends on several factors, and the following bullets can be used to help determine where the best location in a particular environment is: •
If using DxDataBook, and placing symbols from the parts there, then putting all of the parametric information in DxDataBook will enable more sophisticated searches.
•
If not using DxDataBook, then putting the information in a PDB entry will facilitate sharing symbols among similar parts (for example all NPN BJTs can use the same symbol) and thus reducing maintenance.
•
If users place by symbol, then putting the information on the symbol definition will enable the users to place fully populated symbols. This approach has the drawbacks that it requires creation and maintenance of a significantly larger symbol library. Also, the symbol definitions cannot be shared.
•
Placing simulation property information on specific symbol instances can be used with any of the above approaches and is typically done by the analog design engineer who wishes to extend or modify some of the simulation characteristics for this specific design or analysis.
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Property and Simulation Attribute Categories Many of the symbol properties provide simulation attributes for the element. A simulation attribute is a piece of information on the element instance line in the simulation netlist. In many cases there is a one-to-one correspondence of a particular symbol property to the simulation attribute. This document uses the terminologies “property” and “simulation attribute” separately to indicate how a piece of information is represented through the flow. So, a “property” is a piece of data in a schematic, typically attached to a symbol, and through processing may be passed through to the simulation netlist as a “simulation attribute”. The simulation attributes are element specific, and are also simulator specific (this is the main variance between HLASE and Eldo). Properties and Simulation Attributes can be organized into several categories: •
Required – These must appear on the symbol in order for the symbol to be processed properly by HyperLynx Analog.
•
Optional – These are optional properties that are relevant for PCB design, and can be placed on the symbol to provide additional simulation information, or to control the behavior of this element for particular analyses (for example for statistical or noise analysis).
•
Advanced – These are optional properties that can be relevant for PCB design that probably wouldn’t be used by most users, but can provide sophisticated simulation behavior.
•
IC specific – These properties describe physical characteristics of the element as needed for IC design. They are generally not used in PCB designs (since these particular characteristics aren’t a PCB design criteria). However, they may be used when creating models for subsequent use (for example when creating a macromodel).
Similarly to the IC specific attributes, the simulators support a number of element types that don’t necessarily map to physical parts (such as the controlled sources). These types wouldn’t be used directly in a PCB design, but can be used when creating schematics for building macromodels. The document below will enumerate the properties and simulation attributes for the various element types, and indicate the category to which each belongs.
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DxDesigner Symbol Properties Directly Used by HyperLynx Analog Although there is a great deal of flexibility for the properties used by HyperLynx Analog, there are a few properties that are specifically referenced by name, and that may be required depending upon the element type. The basic syntax for an element in the simulation netlist is:
Each of these entries is described below. For more information about these properties, please reference Chapter 3 – “Product Integration” in the HyperLynx Analog™ Simulation I/F User’s Manual.
DxDesigner Symbol Properties Property Name
Required/ Optional
Comments
Prefix
Required
This property is used to tell HyperLynx Analog the type of this element. The value of this property determines the other properties that HyperLynx Analog will use for this symbol.
ID
Required (Generated)
This is the unique identifier for this particular element. It is not a separate property; the identifier is generated by HyperLynx Analog when creating the simulation netlist. HyperLynx Analog uses: 1. The “Name” property of the symbol. 2. The block value of the Reference Designator if the Name is blank 3. The “instance name” of the symbol if the previous values are blank. The 2007.3 and 2007.5 versions of HyperLynx Analog ignore the instance value of the reference designator as placed by the packaging or REFDES utilities.
Pin Order
Required
This property defines the order in which the Pins should be written to the netlist. The contents of this property are the names of the Pins in the order in which they should be written to the netlist. The netlister then writes the nets connected to each of the pins in order in the netlist.
Order
Required
This property is used to tell HyperLynx Analog about the simulation attributes for this particular element. At a minimum, it references either the Value or Model properties (or both in some cases). If the referenced properties aren’t defined on the symbol, HyperLynx Analog simply ignores any relevant entries in the Order property. So, it is perfectly reasonable to define the Order property in a generic fashion, and then just define the simulation attributes of interest. Refer to the HyperLynx Analog documentation (Chapter 3 ~page 44) for a detailed specification of the syntax for this property.
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DxDesigner Symbol Properties Property Name
Required/ Optional
Comments
Value
Required based on Type
This is the value for the element. It is used with passive elements (such as resistors, capacitors, inductors) that generally don’t have models associated with them. It is required for those elements.
Model
Required based on Type
This is the name of the SPICE simulation model to use for this element. It must match the name of the model contained in the library referenced using the Spice Lib Name and Spice Lib Path properties. It is required for elements that require models, optional if the model is optional, and should not be used if the element doesn’t have a model.
Spice Subckt
Required based on Type
This is also the name of the SPICE simulation model. It must match the value of the Model property. It is used for certain functions in HyperLynx Analog (such as the Simulation Properties feature). It is required for subcircuit macromodels.
Spice Lib Name
Required based on Type
This is the name of the file containing the SPICE model. This is just the name without any filesystem path. It is specified as a .lib or a .mod filename. It is required for all elements that require models.
Spice Lib Path
Required based on Type
This is the path to the directory containing the library that holds the SPICE model. It should not contain the file name. “Spice Lib Path” and “Spice Lib Name” are concatenated together to form the fully qualified path to the SPICE library that contains the referenced model. It is required for all elements that require models.
No Pins
Optional
If defined, and not set to 0 or false (case-insensitive), the netlister will not write the nets out using the Pin Order information. This is typically used when the Order property is used to define the pin information.
Simulation Model
Required
This property defines the language for the model. This property is used to enable the “Push Language” command; when it is not defined the command is not enabled. Based on the value, HyperLynx Analog uses different properties to drive simulation. Information on HDL and Mixed-Signal simulation will be added to this document in a future revision. Allowed Values are (case insensitive):
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•
SPICE (this is the default if the property doesn’t exist).
•
VHDL
•
VHDL_AMS
•
VERILOG
•
VERILOGA
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DxDesigner Symbol Properties Property Name
Required/ Optional
Comments
Exclude
Optional
This property is used to exclude specific elements from the simulation. This enhances the capability for a single design to be used for both simulation and layout. This property will often be used for elements in the schematic, rather than on library symbols. However, in some cases, if a symbol will never be used for simulation, it may be helpful to define this property on the library symbol. For example, it can be helpful to define Exclude on connector symbols that will never be simulated. The Exclude property supports the following values: •
No – The element will be included in the simulation (This is the default value)
•
Yes – The element is excluded from the simulation, and its pins are not connected in any way. It behaves as an OPEN circuit.
•
Shunt – The element is excluded from the simulation, and the pins are connected together as a SHORT circuit.
Note: This property is new in EE2007.5 and PADS 9.0.
Common ELDO Simulation Attributes In addition to the required information in the previous section, Eldo has a number of simulation attributes that apply to more than a single device. If you intend to use this functionality, these may be good candidates for individual properties. Depending on your configuration and requirements, these may also be assigned using the Order property, or another generic property. These are listed here for convenience. Please refer to the individual device sections to see if they apply. Also, properties for some of these simulation attributes are defined in the standard .prp files, and some would need to be added if you wish to use them as individual properties. Note that the simulation attribute names are case-insensitive, and are listed here as title case to be consistent with other Mentor defined properties.
Table 1 TEMPERATURE Simulation Attributes Eldo provides the ability to define certain temperature related characteristics on a per device basis. This is a powerful capability that provides the designer with the ability to analyze the design under a variety of environmental conditions. TEMPERATURE Simulation Attributes Simulation Attribute Name Temp
Allowed Values Real Values
Notes
Used to set the specific temperature for a device. It is separate from the overall circuit temperature, and can be used to model heating effects independently from the rest of the circuit (for example heating due to power dissipation in the enclosure). TEMP and DTEMP are mutually exclusive. If both are specified, the last one is utilized.
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TEMPERATURE Simulation Attributes Simulation Attribute Name Dtemp
Allowed Values Real Values
Notes
Used to define a temperature delta for this device from the rest of the circuit. Thus the temperature used for this device will track the circuit temperature and is another way to model heating effects. TEMP and DTEMP are mutually exclusive. If both are specified, the last one is utilized.
TC1, TC2, TC3
Real Values
Used for passive elements (resistor, inductor, capacitor) for defining the way that the element’s value varies with temperature.
Table 2 ADVANCED ANALYSIS CONTROL Simulation Attributes In addition to providing the advanced analyses, Eldo provides the ability to control use of the analyses on a per-element basis. This gives the user even more control over how these analyses are performed. ADVANCED ANALYSIS CONTROL Simulation Attributes Simulation Attribute Name Statistical
Allowed Values 0 or 1
Notes
This attribute controls whether this element should be adjusted during Monte Carlo, Worst Case, or DC mismatch analysis. By using this attribute the user can control exactly which elements are varied statistically to gain a detailed view of the circuit’s performance.
Nonoise
No value
Specifying this attribute excludes the element as a contributor in a noise analysis.
Noise
1 (or sometimes 0)
Specifying this attribute controls the inclusion of this element in a noise analysis.
Fmin
Real Values
Lower limit of the noise frequency band
Fmax
Real Values
Upper limit of the noise frequency band
Nbf
Real Values
Number of noise sources.
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Element Type Specific Property Information This section provides information for the specific simulation attributes for the various types of elements used in PCB design. It describes the physical elements first, with the behavioral elements to follow. For each element the required properties are enumerated. A minimum and a recommended definition for the Order property are provided. This is followed by a listing of some optional properties. As noted, these are optional properties that can be added to the symbol, but are not required for correct basic simulation. If they are used, Mentor recommends defining them as individual properties. If they will be commonly used, then placeholders can be defined on the symbol with component specific information added from the DxDatabook or the PDB. Then if applicable, there is a description of the more advanced properties. Mentor recommends that advanced properties should be defined using the generic ELDO_PARAMS property. Assuming that they won’t be used on most components, it is simpler to gather them onto the ELDO_PARAMS property, and simply fill that in with the desired information to include in the netlist. Information on IC specific simulation attributes will be added in a future revision of this document. Table 3 CAPACITOR Minimum Required Properties: CAPACITOR Minimum Required Properties Property Name
Property Value
Prefix
C
Pin Order
Ordered List of Pin Names for the netlist. (Positive_Node Negative_Node) Note: Although Pin Order is not strictly required, it is strongly recommended for consistency with other element types.
Order
Recommended: Model= Value$ TC1= TC2= TC3= TEMP= DTEMP= ELDO_PARAMS$ Minimum: Value$
Value
Capacitor value in SPICE numerical format Table 4 CAPACITOR Optional Properties: CAPACITOR Optional Properties
Property Name
Notes
Model
A model to use for this capacitor. For example for capacitors in Eldo, statistical information is defined in the model.
IC
Sets the initial guess for the voltage across the capacitor prior to a transient analysis. To use this option, the UIC parameter must also be present in the .TRAN statement.
TC1, TC2, TC3
Coefficients for the temperature adjusted value.
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CAPACITOR Optional Properties Property Name
Notes
TEMP, DTEMP
Device specific temperature settings.
Table 5 CAPACITOR Advanced Properties: CAPACITOR Advanced Properties Property Name
Notes
ELDO_PARAMS
Entered as needed. e.g. STATISTICAL=1 NOISE=1
STATISTICAL
Device specific statistical variation control
There are other advanced properties that could be added, please refer to the Eldo reference manual for more information. This description is intended to provide guidance, and should provide examples to allow advanced users to harness the descriptive capabilities that Eldo provides. Table 6 INDUCTOR Minimum Required Properties: INDUCTOR Minimum Required Properties Property Name
Property Value
Prefix
L
Pin Order
Ordered List of Pin Names for the netlist. (Positive_Node Negative_Node) The order is important for inductors as it can affect the way that inductors are coupled when using the Mutual Inductor element.
Order
Recommended: Model= Value$ IC= TC1= TC2= TC3= R= TEMP= DTEMP= ELDO_PARAMS$ Minimum: Value$
Value
Inductor value in SPICE numerical format Table 7 INDUCTOR Optional Properties: INDUCTOR Optional Properties
Property Name
Notes
Model
A model to use for this capacitor. For example for capacitors in Eldo, statistical information is defined in the model.
IC
Sets the initial ‘guess’ for the current through the inductor prior to a transient analysis. To use this option the UIC parameter must also be present in the .TRAN statement.
R
R is a resistor that is added in series with inductor L.
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INDUCTOR Optional Properties Property Name
Notes
TC1, TC2, TC3
Coefficients for the temperature adjusted value.
TEMP, DTEMP
Device specific temperature settings.
Table 8 INDUCTOR Advanced Properties: INDUCTOR Advanced Properties Property Name
Notes
ELDO_PARAMS
Entered as needed. e.g. STATISTICAL=1
STATISTICAL
Device specific statistical variation control
There are other advanced properties that could be added, please refer to the Eldo reference manual for more information. This description is intended to provide guidance, and should provide examples to allow advanced users to harness the descriptive capabilities that Eldo provides. Table 9 RESISTOR Minimum Required Properties: RESISTOR Minimum Required Properties Property Name
Property Value
Prefix
R
Pin Order
Ordered List of Pin Names for the netlist. (Positive_Node Negative_Node) Note: Although Pin Order is not strictly required, it is strongly recommended for consistency with other element types.
Order
Recommended: Model= Value$ TC1= TC2= TC3= TEMP= DTEMP= ELDO_PARAMS$ Minimum: Value$
Value
Resistor value in SPICE numerical format Table 10 RESISTOR Optional Properties: RESISTOR Optional Properties
Property Name
Notes
Model
A model to use for this resistor. For resistors in Eldo, statistical information is defined in the model.
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TC1, TC2, TC3
Coefficients for the temperature adjusted value.
TEMP, DTEMP
Device specific temperature settings.
Table 11 RESISTOR Advanced Properties: RESISTOR Advanced Properties Property Name
Notes
ELDO_PARAMS
Entered as needed. e.g. STATISTICAL=1 NOISE=1
STATISTICAL
Device specific statistical variation control
NONOISE
Device specific noise analysis control
NOISE
Device specific noise analysis control
FMIN
Lower limit of the noise frequency band
FMAX
Upper limit of the noise frequency band
NBF
Number of noise sources.
KF
Flicker noise coefficient
AF
Flicker noise exponent
WEEXP
Flicker noise exponent
LEEXP
Flicker noise exponent
FEXP
Flicker noise exponent
There are other advanced properties that could be added, please refer to the Eldo reference manual for more information. This description is intended to provide guidance, and should provide examples to allow advanced users to harness the descriptive capabilities that Eldo provides. Table 12 DIODE Minimum Required Properties: DIODE Minimum Required Properties Property Name
Property Value
Prefix
D
Pin Order
Ordered List of Pin Names for the netlist. (Positive_Node Negative_Node)
Order
Recommended: Model$ Off= TEMP= DTEMP= ELDO_PARAMS$ Minimum: Model$
Model
Model name for this diode
Spice Lib Name
Name of the Spice library file containing the diode model
Spice Lib Path
Path to the directory containing the Spice Library file.
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Table 13 DIODE Optional Properties: DIODE Optional Properties Property Name
Notes
OFF
When set to 1, causes no initial operating point to be calculated for the device during DC analysis, i.e. the device is “off”. When set to 0, the option is ignored.
TEMP, DTEMP
Device specific temperature settings.
Table 14 DIODE Advanced Properties: DIODE Advanced Properties Property Name
Notes
ELDO_PARAMS
Entered as needed. e.g. STATISTICAL=1
STATISTICAL
Device specific statistical variation control
NONOISE NOISE
Set to 1 or 0
There are other advanced properties that could be added, please refer to the Eldo reference manual for more information. This description is intended to provide guidance, and should provide examples to allow advanced users to harness the descriptive capabilities that Eldo provides. Table 15 BJT Minimum Required Properties: BJT Minimum Required Properties Property Name
Property Value
Prefix
Q
Pin Order
Ordered List of Pin Names for the netlist. (Collector Base Emitter)
Order
Recommended: Model$ Off= TEMP= DTEMP= ELDO_PARAMS$ Minimum: Model$
Model
Model name for this BJT
Spice Lib Name
Name of the Spice library file containing the BJT model
Spice Lib Path
Path to the directory containing the Spice Library file.
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Table 16 BJT Optional Properties: BJT Optional Properties Property Name
Notes
OFF
When set to 1, causes no initial operating point to be calculated for the device during DC analysis, i.e. the device is “off”. When set to 0, the option is ignored.
TEMP, DTEMP
Device specific temperature settings.
Table 17 BJT Advanced Properties: BJT Advanced Properties Property Name
Notes
ELDO_PARAMS
Entered as needed. e.g. STATISTICAL=1
STATISTICAL
Device specific statistical variation control
NONOISE NOISE
Set to 1 or 0
FMIN
Lower limit of the noise frequency band
FMAX
Upper limit of the noise frequency band
NBF
Number of noise sources.
There are other advanced properties that could be added, please refer to the Eldo reference manual for more information. This description is intended to provide guidance, and should provide examples to allow advanced users to harness the descriptive capabilities that Eldo provides. Table 18 JFET and MESFET Minimum Required Properties In Eldo, JFET and MESFET differ by the model level used. So, the symbols are set up the same for both devices. JFET and MESFET Minimum Required Properties Property Name
Property Value
Prefix
J
Pin Order
Ordered List of Pin Names for the netlist. (Drain Gate Source)
Order
Recommended: Model$ Off= TEMP= DTEMP= ELDO_PARAMS$ Minimum: Model$
Model
Model name for this JFET
Spice Lib Name
Name of the Spice library file containing the JFET model
Spice Lib Path
Path to the directory containing the Spice Library file.
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Table 19 JFET and MESFET Optional Properties: JFET and MESFET Optional Properties Property Name
Notes
OFF
When set to 1, causes no initial operating point to be calculated for the device during DC analysis, i.e. the device is “off”. When set to 0, the option is ignored.
TEMP, DTEMP
Device specific temperature settings.
Table 20 JFET and MESFET Advanced Properties: JFET and MESFET Advanced Properties Property Name
Notes
ELDO_PARAMS
Entered as needed. e.g. STATISTICAL=1
STATISTICAL
Device specific statistical variation control
NONOISE NOISE
Set to 1 or 0
FMIN
Lower limit of the noise frequency band
FMAX
Upper limit of the noise frequency band
NBF
Number of noise sources.
There are other advanced properties that could be added, please refer to the Eldo reference manual for more information. This description is intended to provide guidance, and should provide examples to allow advanced users to harness the descriptive capabilities that Eldo provides. Table 21 MOSFET Minimum Required Properties: MOSFET Minimum Required Properties Property Name
Property Value
Prefix
M
Pin Order
Ordered List of Pin Names for the netlist. (Drain Gate Source [Bulk])
Order
Recommended: Model$ TEMP= DTEMP= ELDO_PARAMS$ Minimum: Model$
Model
Model name for this MOSFET
Spice Lib Name
Name of the Spice library file containing the MOSFET model
Spice Lib Path
Path to the directory containing the Spice Library file.
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Table 22 MOSFET Optional Properties: MOSFET Optional Properties Property Name
Notes
TEMP, DTEMP
Device specific temperature settings. Table 23 MOSFET Advanced Properties: MOSFET Advanced Properties
Property Name
Notes
ELDO_PARAMS
Entered as needed. e.g. STATISTICAL=1
STATISTICAL
Device specific statistical variation control
NONOISE NOISE
Set to 1 only to force the device in noise analysis
FMIN
Lower limit of the noise frequency band
FMAX
Upper limit of the noise frequency band
NBF
Number of noise sources.
There are other advanced properties that could be added, please refer to the Eldo reference manual for more information. This description is intended to provide guidance, and should provide examples to allow advanced users to harness the descriptive capabilities that Eldo provides.
Subcircuit Instances (Macromodels) Subcircuits are unique from a property perspective, in that the parameters aren’t pre-defined. The parameters are defined as part of the subcircuit definition, and so if they are to be passed in on an instance basis, they must be determined by looking at the subcircuit definition. Defining them all as separate properties would create a huge number of additional properties. So, the best approach is to simply enumerate them on the ELDO_PARAMS property. Table 24 Macromodels Minimum Required Properties: MACROMODELS Minimum Required Properties Property Name
Property Value
Prefix
X
Pin Order
Ordered List of Pin Names for the netlist. The pins must match the order of the nodes defined in the subcircuit macromodel definition.
Order
Recommended: Model$ TEMP= ELDO_PARAMS$ Minimum: Model$
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Model
Model name for this Subcircuit
Spice Subckt
Model name for this Subcircuit
Spice Lib Name
Name of the Spice library file containing the Subcircuit model
Spice Lib Path
Path to the directory containing the Spice Library file. Table 25 MACROMODELS Optional Properties:
MACROMODELS Optional Properties Property Name
Notes
TEMP
Device specific temperature settings. Table 26 MACROMODELS Advanced Properties: MACROMODELS Advanced Properties
Property Name
Notes
ELDO_PARAMS
Entered as needed. e.g. STATISTICAL=1
STATISTICAL
Device specific statistical variation control
NONOISE NOISE
Set to 0 only to force the device out of noise analysis
Model Specific parameter
There are other advanced properties that could be added, please refer to the Eldo reference manual for more information. This description is intended to provide guidance, and should provide examples to allow advanced users to harness the descriptive capabilities that Eldo provides.
Conclusion This document outlines the recommended information to place on symbols or parts when creating your libraries. Some advanced properties are also noted to guide those users who wish to use those advanced capabilities.
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Appendix - Considerations for Defining Properties for Use in Simulation As discussed earlier in this document, the Order property defines how other properties are used to pass simulation attributes to the simulator. This provides a great deal of flexibility in how the properties and their content can be defined. And of course, there are trade-offs when defining the properties in different ways. The simplest definition is to have each simulation attribute represented as an individual symbol property. This approach has the benefits that: • It is easy to define the syntax for the simulator. • Each simulation attribute can be specified independently. • It is more straightforward to define the property type, since it is a single value. For numeric values (most attributes), some numeric processing (for example ensuring that the number is in proper SPICE format) can be applied more readily. • Each property/simulation attribute can be individually filtered if using DxDatabook. It has the drawbacks that: • Each simulation attribute needs its own property. The number of possible property names is huge, and can be overwhelming for the librarian and the engineer. • It is more difficult to group related attributes together. For example, some attributes only make sense if another attribute is defined. Since each property can be defined on the symbol separately, this can be confusing and hard to manage. • If using DxDatabook, the attributes will need their own entries in the database, regardless of whether is makes sense to filter on them individually. This makes the database schema more difficult to define and the data more difficult to maintain. At the other extreme, one could group all of the simulation attributes together into a single property. This approach has the benefits that: • There are a lot fewer properties on the symbol. • There are a lot fewer property definitions needed. • Since all of the properties are in one place, simulation attributes that are related together are easy to specify together or not at all. It has the drawbacks that: • This single property becomes unwieldy quickly, making it hard to edit and maintain. • All of the simulation attributes are still specified on the symbol (or as part of the PDB or DxDatabook entry) making it potentially confusing to the librarian. • It is more difficult to have placeholders for, but leave out, optional simulation attributes. If they are individual properties, it is easy to just leave them out if the property value is blank. • Since the single property is more complicated, it is harder for the software to perform numeric processing for the user. • The Order property cannot be specified in a generic way on the symbol and would need to be updated from DxDatabook or the Parts database. Given these trade-offs, it is difficult to have a single solution that works for all users. Some users may never want to use particular features, and thus their required solution can be simpler, using either approach. And different users may have different filtering requirements, leading to different DxDatabook data requirements. This document provides a suggested approach where the required and optional simulation attributes are supported directly as properties, and the advanced are supported using a generic property. Of course, there are other approaches that can also be used.
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Setting Up Libraries for ELDO Simulation with HyperLynx Analog
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Page 18 of 18 Copyright © 2009 Mentor Graphics Corporation
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