Timing adjustment of clock signals in a digital circuit

• US 6,658,581 B1
• Filed: 03/06/2000
• Issued: 12/02/2003
• Est. Priority Date: 03/29/1999
• Status: Expired due to Fees

• Current Assignee: Agency for Industrial Science and Technology, Evolvable System Research Institute Incorporated
• Original Assignee: Agency of Industrial Science & Technology, Evolvable System Research Institute Incorporated
• Inventors: Toda, Kenji, Higuchi, Tetsuya, Takahashi, Eiichi, Murakawa, Masahiro
• Primary Examiner(s): Lee, Thomas
• Assistant Examiner(s): Chang, Eric
• Application Number:
  US09/519,463
• Time in Patent Office: 1,366 Days
• Field of Search: 713/401, 706/13
• US Class Current: 713/401
• CPC Class Codes: G06F 1/10 Distribution of clock signals , e.g. skew
• CPC Class Codes: H03K 2005/00039 having four transistors serially
• CPC Class Codes: H03K 2005/00058 controlled by a digital setting
• CPC Class Codes: H04L 7/0008 Synchronisation information channels, e.g. clock distribution lines
• CPC Class Codes: H04L 7/0037 Delay of clock signal

Abstract

A digital system that performs a specified function by performing digital processing according to one or more clock signals is provided with a plurality of delay elements which are respectively inserted in a plurality of clock circuits that supply the clock signals in the digital system and each of which is composed of a circuit element that changes a delay time according to a value indicated by a control signal, and a plurality of holding circuits that hold a plurality of control signals to be given to the plurality of delay elements. In the plurality of holding circuits, a value of the control signals held by these holding circuits is changed by external devices according to a probabilistic search technique so that the digital system operates correctly in relation to operation timing.

Claims

1. A digital system that performs a specified function by operating a plurality of mutually interdependent flip-flops to perform digital processing according to one or more clock signals, comprising:

a plurality of delay elements which are inserted respectively in a plurality of clock circuits that supply said clock signals to the flip-flops of said digital system and each of which is composed of a circuit element that changes a delay time according to a value indicated by a control signal, and

a plurality of holding circuits that hold a plurality of control signals to be given to said plurality of delay elements, wherein;

values of the plurality of control signals held in the plurality of holding circuits are changed by an external device according to a probabilistic search technique so that said digital system operates correctly in relation to operation timing.

2. A digital system according to claim 1, wherein;

the values of the control signals held by said holding circuits are changed to optimum values for bringing said digital system into a state where it operates correctly in relation to operation timing, said optimum values being values which said external device has searched by changing in order the values of said control signals according to a genetic algorithm.

3. A digital system according to claim 1, wherein;

the values of the control signals held by said holding circuits are changed to optimum values for bringing said digital system into a state where it operates correctly in relation to operation timing, said optimum values being values which said external device has searched by changing in order the values of said control signals according to a genetic programming.

4. A digital system according to claim 1, wherein;

said plurality of control signals are changed by said external device while raising the frequency of said clock signal in stages.

9. A digital system according to claim 1, wherein digital system is composed as an integrated circuit.

10. A digital system according to claim 1, wherein digital system has a pipeline structure.

11. A digital system according to claim 1, wherein digital system is composed as a circuit board.

5. A digital system that performs a specified function by operating a plurality of mutually interdependent flip-flops to perform digital processing according to one or more clock signals, comprising:

a plurality of delay elements which are inserted respectively in a plurality of clock circuits that supply said clock signals to the flip-flops of said digital system and each of which is composed of a circuit element that changes a delay time according to a value indicated by a control signal,

a plurality of holding circuits that hold a plurality of control signals to be given to said plurality of delay circuits, and

a setting means that changes the values of said plurality of control signals held by said plurality of holding circuits according to a probabilistic search technique so that said digital system operates correctly in relation to operation timing.

6. A digital system according to claim 5, wherein;

said setting means changes in order the values of said control signals according to a genetic algorithm and searches optimum values of said control signals for bringing said digital system into a state where it operates correctly in relation to operation timing.

7. A digital system according to claim 5, wherein;

said setting means changes in order the values of said control signals according to a genetic programming and searches optimum values of said control signals for bringing said digital system into a state where it operates correctly in relation to operation timing.

8. A digital system according to claim 5, wherein;

said plurality of control signals are changed by said setting means while raising the frequency of said clock signal in stages.

12. A method for adjusting timing of one or more clock signals of a digital system that performs a specified function by operating a plurality of mutually interdependent flip-flops to perform digital processing according to said clock signals, said method comprising the steps of:

inserting a plurality of delay elements respectively in a plurality of clock circuits that supply said clock signals to the flip-flops of said digital system,

forming said plurality of delay elements respectively out of circuit elements each changing a delay time according to a value indicated by a control signal,

holding a plurality of control signals to be given to said plurality of delay elements in a plurality of holding circuits provided in said digital system, and

changing the values of said plurality of control signals held by said plurality of holding circuits by an external device according to a probabilistic search technique so that said digital system operates correctly in relation to operation timing.

13. A method for adjusting a clock signal of a digital system according to claim 12, wherein;

said external device changes in order the values of said control signals according to a genetic algorithm and searches optimum values of said control signals for bringing said digital system into a-state-where it-operates correctly in relation to operation timing.

14. A method for adjusting a clock signal of a digital system according to claim 12, wherein;

said external device changes in order the values of said control signals according to a genetic programming and searches optimum values of said control signals for bringing said digital system into a state where it operates correctly in relation to operation timing.

15. A method for adjusting a clock signal of a digital system according to claim 12, wherein;

changing said plurality of control signals by said external device is performed while raising the frequency of said clock signal in stages.

20. A method for adjusting a clock signal of a digital system according to claim 12, wherein said digital system is composed as an integrated circuit.

21. A method for adjusting a clock signal of a digital system according to claim 12, wherein said digital system has a pipeline structure.

22. A method for adjusting a clock signal of a digital system according to claim 12, wherein said digital system is composed as a circuit board.

23. A method for adjusting a clock signal of a digital system according to claim 12, wherein said external device is composed of an electronic computer.

25. A recording medium on which is recorded a processing program that is executed by said electronic computer in a method for adjusting a clock signal of a digital system according to claim 23, and changes the values of said plurality of control signals held by said plurality of holding circuits according to a probabilistic search technique so that said digital system operates correctly in relation to operation timing.

16. A method for adjusting timing of a one or more clock signals of a digital system that performs a specified function by operating a plurality of mutually interdependent flip-flops to perform digital processing according to said clock signals, said method comprising the steps of:

inserting a plurality of delay elements respectively in a plurality of clock circuits that supply said clock signals to the flip-flops of said digital system,

forming said plurality of delay elements respectively out of circuit elements each changing a delay time according to a value indicated by a control signal,

holding a plurality of control signals to be given to said plurality of delay elements in a plurality of holding circuits provided in said digital system, and

changing the values of said plurality of control signals held by said plurality of holding circuits by a setting means provided in said digital system according to a probabilistic search technique so that said digital system operates correctly in relation to operation timing.

17. A method for adjusting a clock signal of a digital system according to claim 16, wherein said setting means changes in order the values of said control signals according to a genetic algorithm and searches optimum values of said control signals for bringing said digital system into a state where it operates correctly in relation to operation timing.

18. A method for adjusting a clock signal of a digital system according to claim 16, wherein said setting means changes in order the values of said control signals according to a genetic programming and searches optimum values of said control signals for bringing said digital system into a state where it operates correctly in relation to operation timing.

19. A method for adjusting a clock signal of a digital system according to claim 16, wherein said plurality of control signals are changed by said setting means while raising the frequency of said clock signal in stages.

24. A method for adjusting a clock signal of a digital system according to claim 16, wherein said setting means is composed of an electronic computer.

26. A recording medium on which is recorded a processing program that is executed by said electronic computer in a method for adjusting a clock signal of a digital system according to claim 24, and changes the values of said plurality of control signals held by said plurality of holding circuits according to a probabilistic search technique so that said digital system operates correctly in relation to operation timing.