Method for estimating peak crosstalk noise based on separate crosstalk model

• US 6,971,076 B2
• Filed: 12/05/2002
• Issued: 11/29/2005
• Est. Priority Date: 12/18/2001
• Status: Expired due to Fees

• Current Assignee: Cadence Design Systems Incorporated (Cadence Group)
• Original Assignee: Cadence Design Systems Incorporated (Cadence Group)
• Inventors: Chen, Pinhong
• Primary Examiner(s): Siek, Vuthe
• Application Number:
  US10/313,866
• Publication Number:
  US 20030115563A1
• Time in Patent Office: 1,090 Days
• Field of Search: 716 4- 6, 716/8, 716/11
• US Class Current: 716/115
• CPC Class Codes: G06F 30/367 Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods

Abstract

Crosstalk noise peaks in output signals of nets of an integrated circuit layout design are estimated by first processing the design to estimate resistances and capacitances of the nets. The design is then processed to identify each aggressor net having at least one section that is proximate to a section of a victim net. A separate aggressor model is then generated for each proximate aggressor net section, the aggressor model including a current source and a capacitor. The design is then processed to identify each victim net that is proximate any aggressor net and a separate crosstalk model is generated for each identified victim net. The crosstalk model for each victim net includes the victim net'"'"'s estimated resistances and capacitances and incorporates the aggressor model of each aggressor net section that is proximate to a section of the identified victim net. The crosstalk model for each identified victim net is then evaluated to determine a response to a signal applied as input to the victim net of a victim net output signal. The peak crosstalk noise in each identified victim net is estimated based on the response of the net'"'"'s output signal.

Claims

1. A method of processing an integrated circuit (IC) layout design describing a victim net of an IC as having a plurality of sections and describing at least one aggressor net of the IC as having a plurality of sections, wherein at least one aggressor net section is proximate to at lest one victim net section, wherein the method estimates peak crosstalk noise in a an output signal of the victim net, the method comprising the steps of:

a. processing the IC layout design to generate a separate model representing each aggressor net section that is proximate to a section of the victim net;

b. processing the IC layout design to generate a crosstalk model for the victim net, wherein the crosstalk model includes a separate section corresponding to each victim net section modeling an impedance of its corresponding victim net section, and wherein each crosstalk model section corresponding to a section of the victim net that is proximate to an aggressor net section also includes the model of that aggressor net section generated at step a;

c. evaluating the crosstalk model to determine a behavior of the output signal in response to an input signal applied as input to the victim net; and

d. estimating the peak crosstalk noise from the behavior of the output signal determined at step c.

2. The method in accordance with claim 1 wherein the separate model of each aggressor net section comprises a current source and a capacitor.

3. The method in accordance with claim 2 wherein the capacitor of the separate model of each aggressor net section that is proximate to a victim net section represents an estimated coupling capacitance between the aggressor net section and the proximate victim net section.

4. The method in accordance with claim 3 wherein the capacitor also represents an estimated shunt capacitance of the aggressor net section.

5. The method in accordance with claim 1 wherein step a comprises the substeps of:

a1. generating a separate model of each aggressor net that has at least one section that is proximate to any section of the victim net, wherein each aggressor net section is separately modeled by and estimated series resistance and shunt capacitance of the aggressor net section, and wherein each aggressor net section that is proximate to a victim net section is also modeled by additional shunt capacitance representing an estimated coupling capacitance between that aggressor net section and its proximate victim net section;

a2. evaluating each aggressor net model generated at step all to determine a rate of change and rise time within each section of the aggressor net of an edge of a second input signal conveyed by the aggressor net; and

a3. generating the separate model representing each aggressor net section that is proximate to a victim net section, the separate model comprising a capacitor and a current source, wherein the current source generates a current pulse of magnitude that is a function of the capacitance of the capacitor and the determined rate of change of the second input signal within that section of the aggressor net, and wherein the current pulse is of duration that is a function of the determined rise time of the second input signal within that section of the aggressor net.

6. A method of processing an integrated circuit (IC) layout design describing a plurality of nets of an IC, each having a plurality of sections to estimate peak crosstalk noise in output signals of the nets, the method comprising the steps of:

a. processing the IC layout to estimate series resistance and shunt capacitances of said sections of the nets;

b. processing the IC layout design to identify each net that is an aggressor net having at least one section that is proximate to at least one section of a victim net;

c. processing the IC layout design to determine for each section of the identidied aggressor net that is proximate to a section of a victim net, a coupling capacitance between that section of the aggressor net and the proximate section of the victim net;

d. generating a separate aggressor model representing each section of each aggressor net that is proximate to a section of a victim net, the aggressor model being based on the series resistance and shunt capacitance of the aggressor net section estimated at step a and on the coupling capacitance between the aggressor net section and the proximate section of the victim net;

e. processing the IC layout design to identify each net that is a victim net having at least one section proximate to a section of an aggressor net,

f. generating a separate crosstalk model for each identified victim net, wherein the crosstalk model includes the estimated series resistance and shunt capacitance of each section of the victim net and incorporating the aggressor model generated at step d of each aggressor net section that is proximate to a section of the identified victim net;

g. evaluating the crosstalk model for each identified victim net to determine a response of an output signal of that net to a input signal applied as input to the identified victim net; and

h. estimating peak crosstalk noise in each identified victim net from the response of its output signal determined at step g.

7. Computer-readable media storing software which when read and executed by a computer causes the computer to carry out a method for processing an integrated circuit (IC) layout design describing a victim net of an IC as having a plurality of sections, wherein at least one aggressor net section in proximate to at least one victim net section, wherein the method estimate peak crosswalk noise in an output signal of the victim net, wherein the method comprises the steps of:

a. processing the IC layout design to generate a separate model representing each aggressor net section that is proximate to a section of the victim net;

b. processing the IC layout design to generate a crosstalk model for the victim net, wherein the crosstalk model includes a separate section corresponding to each victim net section, modeling an impedance of its corresponding victim net section, and wherein each crosstalk model section corresponding to a section of the victim net that is proximate to an aggressor net section also includes the model of that aggressor net section generated at step a;

c. evaluating the crosstalk model to determine a behavior of the output signal in response to an input signal applied as input to the victim net; and

d. estimating the peak crosstalk noise from the behavior of the output signal determined at step c.

8. The computer readable media in accordance with claim 7 wherein the separate model of each aggressor net section comprises a current source and a capacitor.

9. The computer readable media in accordance with claim 8 wherein the capacitor of the separate model of each aggressor net section that is proximate to a victim net section represents an estimated coupling capacitance between the aggressor net section and the proximate victim net section.

10. The computer readable media in accordance with claim 9 wherein the capacitor also represents an estimated shunt capacitance of the aggressor net section.

11. The computer readable media in accordance with claim 7 wherein step a comprises the substeps of:

a1. generating a separate model of each aggressor net that has at least one section that is proximate to any section of the victim net, wherein each aggressor net section is separately modeled by and estimated series resistance and shunt capacitance of the aggressor net section, and wherein each aggressor net section that is proximate to a victim net section is also modeled by additional shunt capacitance representing an estimated coupling capacitance between that aggressor net section and its proximate victim net section;

a2. evaluating each aggressor net model generated at step all to determine a rate of change and rise time within each section of the aggressor net of an edge of a second input signal conveyed by the aggressor net; and

a3. generating the separate model representing each aggressor net section that is proximate to a victim net section, the separate model comprising a capacitor and a current source, wherein the current source generates a current pulse of magnitude that is a function of the capacitance of the capacitor and the determined rate of change of the second input signal within that section of the aggressor net, and wherein the current pulse is of duration that is a function of the determined rise time of the second input signal within that section of the aggressor net.

12. Computer-readable media storing software which when read and executed by a computer causes the computer to carry out a method of processing an integrated circuit (IC) layout design describing a plurality of nets of an IC each having a plurality of sections to estimate peak crosstalk noise in output signals of the nets, wherein method comprises the steps of:

a. processing the IC layout to estimate series resistances and shunt capacitances of sections of the nets;

b. processing the IC layout design to identify each net that is an aggressor net having at least one section that is proximate to a section of another net;

c. processing the IC layout design to determine for each aggressor net section that is proximate to a section of a victim net, a coupling capacitance between that section of the aggressor net and the proximate section of said another net;

d. generating a separate aggressor model representing each section of each aggressor net that is proximate to a section of another net, the aggressor model being based on the series resistance and shunt capacitance of the aggressor net section estimated at step a and on the coupling capacitance between the aggressor net section and the proximate section of the victim net;

e. processing the IC layout design to identify each net that is a victim net having at least one section proximate to a section of an aggressor net

f. generating a separate crosstalk model for each identified victim net, wherein the crosstalk model includes the estimated series resistance and shunt capacitance of each section of the victim net and incorporating the aggressor model generated at step d of each aggressor net section that is proximate to a section of the identified victim net.

g. evaluating the crosstalk model for each identified victim net to determine a response of an output signal of that net to a input signal applied as input to the identified victim net; and

h. estimating the peak crosstalk noise in each identified victim net from the response of its output signal determined at step g.

13. A method for estimating peak crosstalk noise in output signals of nets of an integrated circuit (IC) layout design comprises the steps of:

a. processing the IC layout design to estimate resistances and capacitances of the nets;

b. processing the design to identify each net having at least one section that is proximate to a section of a victim net;

c. generating a separate aggressor model representing each aggressor net section that is proximate to a section of an identified victim net, each separate aggressor model including a current source and a capacitor;

d. processing the design to identify nets having at least one section that is proximate to an aggressor net section as being victim nets;

e. generating a separate crosstalk model for each identified victim net including the victim net'"'"'s estimated resistances and capacitances and incorporating the aggressor model of each aggressor net section that is proximate to a section of the identified victim net; and

f. evaluating the crosstalk model for each identified victim net to determine a behavior of an output signal of that victim net in response to an input signal supplied as input to the victim net.

14. The method in accordance with claim 13 wherein step f further comprises:

estimating the peak crosstalk noise in each identified victim net from the determined behavior of the victim net'"'"'s output signal.

15. Computer-readable media storing software which when read and executed by a computer causes the computer to carry out a method for estimating peak crosstalk noise in output signals of nets of an integrated circuit (IC) layout design, wherein the method comprises the steps of:

a. processing the IC layout design to estimate resistances and capacitances of the nets;

b. processing the design to identify each net having at least one section that is proximate to a section of a victim net;

c. generating a separate aggressor model representing each aggressor net section that is proximate to a section of an identifeied victim net, each separate aggressor model including a current source and a capacitor;

d. processing the design to identify nets having at least one section that is proximate to an aggressor net section as being victim nets;

e. generating a separate crosstalk model for each identified victim net including the victim net'"'"'s estimated resistances and capacitances and incorporating the aggressor model of each aggressor net section that is proximate to a section of the identified victim net;

f. evaluating the crosstalk model for each identified victim net to determine a behavior of an output signal of that victim net in response to an input signal supplied as input to the victim net; and

g. estimating the peak crosstalk noise in each identified victim net from the determined behavior of the victim net'"'"'s output signal.