Placement-based pin optimization method and apparatus for computer-aided circuit design

• US 6,298,468 B1
• Filed: 05/04/1999
• Issued: 10/02/2001
• Est. Priority Date: 05/04/1999
• Status: Expired due to Fees

• Current Assignee: Prosper Design Systems Pte. Ltd.
• Original Assignee: Prosper Design Systems Pte. Ltd.
• Inventors: Zhen, Cai
• Primary Examiner(s): PHAN, TRONG Q
• Application Number:
  US09/305,802
• Time in Patent Office: 882 Days
• Field of Search: 716/2, 716/7, 716/8, 716/10, 716/12
• US Class Current: 716/122
• CPC Class Codes: G06F 30/392 Floor-planning or layout, e.g. partitioning or placement

Abstract

Soft pin locations in a hybrid paradigm are optimized according to circuit density centers of circuit components coupled to the soft pins. As a result, the soft pins are located closer to components with heavier loads and further from components with lighter loads. Circuit density centers are determined by summing coordinates weighted by circuit loads, including capacitance and resistance, and dividing the summed weighted coordinates by a sum of the weights. To avoid blockage, optimized soft pin locations can be moved to soft block boundaries relative to the optimized locations.

Claims

1. A method for improving locations of one or more pins of a soft block of a circuit design which includes one or more circuit blocks, the method comprising:

for each subject one of the one or more pins,

(i) determining that one or more components of the circuit design are connected to the subject pin;

(ii) locating a circuit density center of the one or more components; and

(iii) assigning the circuit density center as a new location of the pin.

2. The method of claim 1 wherein locating a circuit density center comprises:

determining the circuit density center according to capacitance and resistance of the components.

3. The method of claim 1 further comprising:

for each subject one of the one or more pins,

(iv) moving the subject pin to an aligned location along a boundary of a selected one of the one or more circuit blocks which corresponds to the subject pin wherein the aligned position is relative to the new location of the subject pin.

4. The method of claim 3 wherein (iv) moving comprises:

determining that a signal wire can be routed through the circuit design between the subject pin at the aligned position and a connected pin prior to moving the subject pin.

16. The method of claim 2 wherein the circuit density center is determined according to capacitance, resistance, and relative location of the components.

5. A computer readable medium useful in association with a computer which includes a processor and a memory, the computer readable medium including computer instructions which are configured to cause the computer to improve locations of one or more pins of a soft block of a circuit design which includes one or more circuit blocks by:

for each subject one of the one or more pins,

(i) determining that one or more components of the circuit design are connected to the subject pin;

(ii) locating a circuit density center of the one or more components; and

(iii) assigning the circuit density center as a new location of the pin.

6. The computer readable medium of claim 5 wherein locating a circuit density comprises:

determining the circuit density center according to capacitance and resistance of the components.

7. The computer readable medium of claim 5 wherein the computer instructions are configured to cause the computer to improve locations of one or more pins of a soft block of a circuit design which includes one or more circuit blocks by also:

for each subject one of the one or more pins,

(iv) moving the subject pin to an aligned location along a boundary of a selected one of the one or more circuit blocks which corresponds to the subject pin wherein the aligned position is relative to the new location of the subject pin.

8. The computer readable medium of claim 7 wherein (iv) moving comprises:

determining that a signal wire can be routed through the circuit design between the subject pin at the aligned position and a connected pin prior to moving the subject pin.

9. A computer system comprising:

one or more processors;

a memory operatively coupled to the processors; and

a pin location improvement module (i) which executes in the processors from the memory and (ii) which, when executed by the processors, causes the computer system to improve locations of one or more pins of a soft block of a circuit design which includes one or more circuit blocks by;

for each subject one of the one or more pins,

(i) determining that one or more components of the circuit design are connected to the subject pin;

(ii) locating a circuit density center of the one or more components; and

(iii) assigning the circuit density center as a new location of the pin.

10. The computer system of claim 9 wherein locating a circuit density center comprises:

determining the circuit density center according to capacitance and resistance of the components.

11. The computer system of claim 9 wherein the pin location improvement module is configured to cause the computer system to improve locations of one or more pins of a soft block of a circuit design which includes one or more circuit blocks by also:

for each subject one of the one or more pins,

(iv) moving the subject pin to an aligned location along a boundary of a selected one of the one or more circuit blocks which corresponds to the subject pin wherein the aligned position is relative to the new location of the subject pin.

12. The computer system of claim 11 wherein (iv) moving comprises:

determining that a signal wire can be routed through the circuit design between the subject pin at the aligned position and a connected pin prior to moving the subject pin.

13. A method for designing a circuit which includes one or more circuit blocks, the method comprising:

determining that an inside element of a subject one of the one or more circuit blocks is to be connected to an outside element which is outside the subject circuit block; and

logically connecting the inside element with the outside element by;

(i) logically placing a pin within the subject block;

(ii) logically connecting the inside element to the pin; and

(iii) logically connecting the outside element to the pin.

14. A computer readable medium useful in association with a computer which includes a processor and a memory, the computer readable medium including computer instructions which are configured to cause the computer to facilitate designing a circuit which includes one or more circuit blocks by:

determining that an inside element of a subject one of the one or more circuit blocks is to be connected to an outside element which is outside the subject circuit block; and

logically connecting the inside element with the outside element by;

(i) logically placing a pin within the subject block;

(ii) logically connecting the inside element to the pin; and

(iii) logically connecting the outside element to the pin.

15. A computer system comprising:

one or more processors;

a memory operatively coupled to the processors; and

a pin location improvement module (i) which executes in the processors from the memory and (ii) which, when executed by the processors, causes the computer system to facilitate designing a circuit which includes one or more circuit blocks by;

determining that an inside element of a subject one of the one or more circuit blocks is to be connected to an outside element which is outside the subject circuit block; and

logically connecting the inside element with the outside element by;

(i) logically placing a pin within the subject block;

(ii) logically connecting the inside element to the pin; and

(iii) logically connecting the outside element to the pin.