Generation and manipulation of realistic signals for circuit and system verification

• US 7,720,654 B2
• Filed: 10/14/2006
• Issued: 05/18/2010
• Est. Priority Date: 10/15/2005
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Hollis, Timothy M.
• Primary Examiner(s): PHAN, THAI Q
• Application Number:
  US11/549,646
• Publication Number:
  US 20070100596A1
• Time in Patent Office: 1,312 Days
• Field of Search: 703/2, 703/14, 703/17, 375/259, 375/347, 708/100, 708/400, 341/144
• US Class Current: 703/2
• 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

Methods for generating realistic waveforms with controllable voltage noise and timing jitter in a computer-based simulation environment and the simulation of a subset of those waveforms with system elements along the signal path is disclosed. By deriving a generic, re-useable, parameterized Fourier series, time-domain clock and pseudo-random data signals are generated from a subset of their true harmonic components. Time-domain signal parameters including high, low, and common-mode voltage levels, transition slew-rates, transition timing, period and/or frequency, may be designated by the user, and the computer calculates the harmonic components that will combine through the inverse Fourier transform to provide the required time-domain characteristics. By computing the frequency content of the signal directly it is possible to simulate the interaction of the signal with various system blocks while remaining in the frequency domain, thereby reducing simulation time and memory requirements. By allowing the parameters of the signal model to vary on a cycle-to-cycle basis, signal characteristics such as voltage noise and timing jitter may be modeled with flexibility and precision down to the numerical limitations of the simulator.

Claims

1. A method implementable in a computer system for generating a time-domain cycle having a noise component present therein, wherein the input to the method comprises a cycle of an input waveform, comprising:

representing the input waveform cycle with at least one mathematical function, wherein the at least one mathematical function varies in accordance with at least one time domain aspect;

providing the at least one time-domain aspect of the input waveform cycle into the computer system, wherein the time-domain aspect comprises the noise component and is controllable through user input to the computer system;

calculating a set of transform coefficients for the input waveform cycle using a finite number of harmonic frequencies using the computer system, wherein the transform coefficients are calculated as a function of the at least one mathematical function and the at least one time-domain aspect; and

computing the time-domain cycle using the set of transform coefficients using the computer system.

2. A method implementable in a computer system for generating a time-domain signal for simulation having a noise component present therein, wherein the input to the method comprises an input waveform of a plurality of cycles that is purely periodic, comprising:

providing at least one time-domain aspect of the input waveform into the computer system for each cycle of the input waveform, wherein the time-domain aspect vanes between the cycles;

calculating a set of transform coefficients for each cycle of the input waveform using a finite number of harmonic frequencies using the computer system, wherein the transform coefficients are calculated as a function of the at least one time-domain aspect of the waveform;

computing a time-domain cycle for each set of transform coefficients using the computer system; and

creating the time-domain signal by concatenating the plurality of time-domain cycles.

3. The method of claim 2, wherein the time-domain aspect of the input waveform comprises a high or low voltage level of the input waveform.

4. The method of claim 2, wherein the time-domain aspect of the input waveform comprises a risetime or a falltime of the input waveform.

5. The method of claim 2, wherein the time-domain aspect of the input waveform comprises a period of the input waveform.

6. The method of claim 2, wherein the time-domain aspect of the input waveform varies randomly between the cycles.

7. The method of claim 2, wherein the time-domain aspect of the input waveform varies deterministically between the cycles.

8. The method of claim 2, wherein the transform coefficients are Fourier coefficients.

9. The method of claim 8, wherein computing the time-domain cycle for each set of Fourier coefficients comprises using an inverse Fourier transform process.

10. A method implementable in a computer system for generating a time-domain signal with a time step for simulation having a noise component present therein, wherein the input to the method comprises an input waveform of a plurality of cycles, comprising:

providing at least one time-domain aspect of the input waveform into the computer system for each cycle of the input waveform, wherein the time-domain aspect vanes between the cycles;

calculating a set of transform coefficients for each cycle of the input waveform using a finite number of harmonic frequencies using the computer system, wherein the transform coefficients are calculated as a function of the at least one time-domain aspect of the waveform;

computing a time-domain cycle for each set of transform coefficients using the computer system, wherein the time domain aspects have a time resolution smaller than the time step; and

creating the time-domain signal with the time step by concatenating the plurality of time-domain cycles.

11. The method of claim 10, wherein the time-domain aspect of the input waveform comprises a high or low voltage level of the input waveform.

12. The method of claim 10, wherein the time-domain aspect of the input waveform comprises a risetime or a falltime of the input waveform.

13. The method of claim 10, wherein the time-domain aspect of the input waveform comprises a period of the input waveform.

14. The method of claim 10, wherein the time-domain aspect of the input waveform varies randomly between the cycles.

15. The method of claim 10, wherein the time-domain aspect of the input waveform varies deterministically between the cycles.

16. The method of claim 10, wherein the transform coefficients are Fourier coefficients.

17. The method of claim 16, wherein computing the time-domain cycle for each set of Fourier coefficients comprises using an inverse Fourier transform process.

18. A method implementable in a computer system for generating a time-domain signal for simulation having a noise component present therein, wherein the input to the method comprises a random bit stream, comprising:

converting in the computer the bit stream into a plurality of data symbols, where each data symbol has at least one time-domain aspect for each of the data symbols, wherein the time-domain aspect varies randomly between the data symbols;

calculating a set of transform coefficients for each of the data symbols using a finite number of harmonic frequencies using the computer system, wherein the transform coefficients are calculated as a function of the at least one time-domain aspect of the each data symbol;

computing a time-domain cycle for each set of transform coefficients using the computer system; and

creating the time-domain signal by concatenating the plurality of time-domain cycles.

19. The method of claim 18, wherein the time-domain aspect of the input waveform comprises a high or low voltage level of the input waveform.

20. The method of claim 18, wherein the time-domain aspect of the input waveform comprises a risetime or a falltime of the input waveform.

21. The method of claim 18, wherein the time-domain aspect of the input waveform comprises a period of the input waveform.

22. The method of claim 18, wherein the time-domain aspect of the input waveform varies randomly between the cycles.

23. The method of claim 18, wherein the time-domain aspect of the input waveform varies deterministically between the cycles.

24. The method of claim 18, wherein the transform coefficients are Fourier coefficients.

25. The method of claim 24, wherein computing the time-domain cycle for each set of Fourier coefficients comprises using an inverse Fourier transform process.

26. A method implementable in a computer system for simulating the effect that a system has on an input waveform to produce an output waveform, comprising:

providing at least one time-domain aspect of the input waveform into the computer system, wherein the input waveform is purely periodic;

calculating transform coefficients for the input waveform using a finite number of harmonic frequencies using the computer system, wherein the transform coefficients are calculated as a function of the at least one time-domain aspect of the waveform;

calculating in the computer system the effect of the system on the input waveform by modifying the transform coefficients in accordance with a transfer function of the system to create first output coefficients; and

processing at least the first output coefficients to derive the output waveform using the computer system.

27. The method of claim 26, further comprising

modeling a source of noise in the computer system having sinusoids, wherein frequencies of the sinusoids differ from the harmonic frequencies of the transform coefficients, wherein the noise is represented by second input coefficients;

calculating in the computer system the effect of the system on the noise by modifying the second input coefficients in accordance with the transfer function of the system to create second output coefficients;

processing both the first output coefficients and the second output coefficients to derive the output waveform using the computer system.

28. The method of claim 27, wherein the frequencies of the sinusoids have random amplitudes.

29. The method of claim 26, wherein the finite number of harmonic frequencies is limited in accordance with an attenuation of the system.

30. The method of claim 26, wherein the transform coefficients are Fourier coefficients.

31. The method of claim 30, wherein processing the at least first output coefficients comprises using an inverse Fourier transform.

32. A computer-readable medium containing instructions for performing a method for generating a time-domain cycle having a noise component present therein, wherein the input to the method comprises a cycle of an input waveform, the method comprising:

representing the input waveform cycle with at least one mathematical function, wherein the at least one mathematical function varies in accordance with at least one time domain aspect;

providing the at least one time-domain aspect of the input waveform cycle into the computer system, wherein the time-domain aspect comprises the noise component and is controllable through user input to the computer system;

calculating a set of transform coefficients for the input waveform cycle using a finite number of harmonic frequencies using the computer system, wherein the transform coefficients are calculated as a function of the at least one mathematical function and the at least one time-domain aspect; and

computing the time-domain cycle using the set of transform coefficients using the computer system.

33. A computer-readable medium containing instructions for performing a method for generating a time-domain signal for simulation having a noise component present therein, wherein the input to the method comprises an input waveform of a plurality of cycles that is purely periodic, the method comprising:

providing at least one time-domain aspect of the input waveform into the computer system for each cycle of the input waveform, wherein the time-domain aspect vanes between the cycles;

calculating a set of transform coefficients for each cycle of the input waveform using a finite number of harmonic frequencies using the computer system, wherein the transform coefficients are calculated as a function of the at least one time-domain aspect of the waveform;

computing a time-domain cycle for each set of transform coefficients using the computer system; and

creating the time-domain signal by concatenating the plurality of time-domain cycles.

34. A computer-readable medium containing instructions for performing a method for generating a time-domain signal with a time step for simulation having a noise component present therein, wherein the input to the method comprises an input waveform of a plurality of cycles, the method comprising:

providing at least one time-domain aspect of the input waveform into the computer system for each cycle of the input waveform, wherein the time-domain aspect vanes between the cycles;

calculating a set of transform coefficients for each cycle of the input waveform using a finite number of harmonic frequencies using the computer system, wherein the transform coefficients are calculated as a function of the at least one time-domain aspect of the waveform;

computing a time-domain cycle for each set of transform coefficients using the computer system, wherein the time domain aspects have a time resolution smaller than the time step; and

creating the time-domain signal with the time step by concatenating the plurality of time-domain cycles.

35. A computer-readable medium containing instructions for performing a method for generating a time-domain signal for simulation having a noise component present therein, wherein the input to the method comprises a random bit stream, the method comprising:

converting in the computer the bit stream into a plurality of data symbols, where each data symbol has at least one time-domain aspect for each of the data symbols, wherein the time-domain aspect varies randomly between the data symbols;

calculating a set of transform coefficients for each of the data symbols using a finite number of harmonic frequencies using the computer system, wherein the transform coefficients are calculated as a function of the at least one time-domain aspect of the each data symbol;

computing a time-domain cycle for each set of transform coefficients using the computer system; and

creating the time-domain signal by concatenating the plurality of time-domain cycles.

36. A computer-readable medium containing instructions for performing a method for simulating the effect that a system has on an input waveform to produce an output waveform, comprising:

providing at least one time-domain aspect of the input waveform into the computer system, wherein the input waveform is purely periodic;

calculating transform coefficients for the input waveform using a finite number of harmonic frequencies using the computer system, wherein the transform coefficients are calculated as a function of the at least one time-domain aspect of the waveform;

calculating in the computer system the effect of the system on the input waveform by modifying the transform coefficients in accordance with a transfer function of the system to create first output coefficients; and

processing at least the first output coefficients to derive the output waveform using the computer system.