US5548524A
Expired / Lapsed
US
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Expression promotion for hierarchical netlisting
Assignee: Cadence Design Systems Inc
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Filing: 1994-04-06
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Granted: 1996-08-20
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Expires: 2014-04-06
Abstract
Abstract A method for generating hierarchical netlists for gate level or transistor level circuits having instances with properties defined by algebraic expressions. The present invention avoids duplication of instance definitions using a method of expression promotion in a computer aided design system capable of simple parameter passing, whereby expressions are replaced by tokens in the netlist, and moved up the hierarchy to a level where they can be fully evaluated. The present invention also provides a specific embodiment for implementing the expression promotion method used for netlisting.
Inventors
- 👤 Celimo P. Hernandez
- 👤 Robyn D. Coultas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:31
CPC Classifications
G; G06; G06F; G06F30/00; G06F30/30; G06F30/32; G06F30/33
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
151 words
In a computer aided design system capable of simple parameter passing, a method for generating a hierarchical netlist for a circuit schematic hierarchically diagramed from a leaf level to a top level, the method comprising machine executed steps of: (a) starting from the leaf level; (b) identifying all components having property values defined by algebraic expressions which contain references to variables defined at a higher level in the hierarchy; (c) gathering all occurrences of said algebraic expressions in a list; (d) replacing each algebraic expression in a line in the hierarchical netlist with a macro argument token, said token identifying an associated member of said list; (e) evaluating an expression when said expression does not contain references to a variable on a higher level of hierarchy; (f) moving up the hierarchy to a parent level above the leaf level, and repeating steps (b) through (e) until all expressions have been evaluated.
Claim 2
Dependent Claim
151 words
In a computer aided design system capable of simple parameter passing, a method for generating a hierarchical netlist for a circuit schematic hierarchically diagramed from a leaf level to a top level, the method comprising machine executed steps of: (a) starting from the leaf level; (b) identifying all components having property values defined by algebraic expressions which contain references to variables defined at a higher level in the hierarchy; (c) gathering all occurrences of said algebraic expressions in a list; (d) replacing each algebraic expression in a line in the hierarchical netlist with a macro argument token, said token identifying an associated member of said list; (e) evaluating an expression when said expression does not contain references to a variable on a higher level of hierarchy; (f) moving up the hierarchy to a parent level above the leaf level, and repeating steps (b) through (e) until all expressions have been evaluated.
Claim 3
Dependent Claim
38 words
The method of claim 1 further comprising the steps of: (g) dividing all circuit components into primitives and sub-circuits; and (h) defining each sub-circuit by circuit components contained in said sub-circuit and corresponding values for said circuit components.
Claim 4
Dependent Claim
125 words
In a computer aided design system capable of simple parameter passing, a netlister for generating hierarchical netlists for a circuit design database having instance property values defined by algebraic expressions, the netlister comprising: a design module, coupled to receive the circuit design database, for generating the hierarchical netlist; a circuit module, coupled to said design module, for defining circuit instances; a derived database, coupled to said design module and said circuit module, for storing circuit information derived from the circuit design database; an instance module, coupled to said circuit module, for deriving circuit instance information; a parameter module, coupled to said instance module, for deriving instance parameters; and an expression evaluation module, coupled to said parameter module and said derived database, for evaluating parameter values.
Claim 5
Dependent Claim
125 words
In a computer aided design system capable of simple parameter passing, a netlister for generating hierarchical netlists for a circuit design database having instance property values defined by algebraic expressions, the netlister comprising: a design module, coupled to receive the circuit design database, for generating the hierarchical netlist; a circuit module, coupled to said design module, for defining circuit instances; a derived database, coupled to said design module and said circuit module, for storing circuit information derived from the circuit design database; an instance module, coupled to said circuit module, for deriving circuit instance information; a parameter module, coupled to said instance module, for deriving instance parameters; and an expression evaluation module, coupled to said parameter module and said derived database, for evaluating parameter values.
Claim 6
Dependent Claim
39 words
The netlister of claim 3 wherein the instance module comprises: a sub-circuits module, coupled to said circuit module and parameter module, for defining sub-circuits; and a primitives module, coupled to said circuit module and parameter module, for defining primitives.
Claim 7
Dependent Claim
13 words
The netlister of claim 3 wherein the hierarchical netlist is in textual format.
Claim 8
Dependent Claim
13 words
The netlister of claim 3 wherein the hierarchical netlist is in binary format.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-08-20 | 2000-02-19 | 2000-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-08-20 | 2004-02-19 | 2004-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-08-20 | 2008-02-19 | 2008-08-20 | $7700.00 | Window Closed / Lapsed |