SIMULATION TOOL FOR HIGH-SPEED COMMUNICATIONS LINKS

• US 20110257953A1
• Filed: 04/19/2010
• Published: 10/20/2011
• Est. Priority Date: 04/19/2010
• Status: Active Grant

• Current Assignee: Altera Corporation (Intel Corporation)
• Original Assignee: Altera Corporation (Intel Corporation)
• Inventors: Shimanouchi, Masashi, Tran, Thungoc M., Li, Peng, Shumarayev, Sergey
• Granted Patent: US 8,626,474 B2
• Time in Patent Office: Days
• US Class Current: 703/14
• CPC Class Codes: G06F 2111/08 Probabilistic or stochastic CAD
• CPC Class Codes: G06F 30/20 Design optimisation, verification or simulation optimisation, verification or simulation of circuit designs G06F30/30
• 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

A link simulation tool for simulating high-speed communications link systems is provided. Communications links may include link subsystems such as transmit (TX) circuitry, receive (TX) circuitry, oscillator circuits that provide reference clock signals to the TX and RX circuitry, and channels that link the TX and RX circuitry. The link simulation tool may model each of the subsystems using behavioral models. The behavioral models may include characteristic functions such as transfer functions, probability density functions, and eye characteristics. The link simulation tool may have a link analysis engine that is capable of performing two-dimensional (two-variable) convolution operations and in applying dual-domain (frequency-time) transformations on the characteristic functions provided by the behavioral models to simulate the performance of the link system. The link simulation tool may have an input screen that allows a user to specify desired link parameters and a data display screen that display simulated results.

Claims

1. A method of simulating communications links using a link simulation tool implemented on computing equipment, wherein each communications link includes respective link subsystems and wherein the link subsystems in each of the communications links are represented by subsystem models in the link simulation tool, the method comprising:

performing two-dimensional convolution operations on the subsystem models to determine link performance for the communications links using the link simulation tool.

2. The method defined in claim 1, wherein the link subsystems of each communications link comprise a transmitter subsystem that is represented by a transmitter subsystem model in the link simulation tool and wherein performing the two-dimensional convolution operations comprises performing two-dimensional convolution operations with the transmitter subsystem model.

3. The method defined in claim 1, wherein the link subsystems of each communications link comprise a receiver subsystem that is represented by a receiver subsystem model in the link simulation tool and wherein performing the two-dimensional convolution operations comprises performing two-dimensional convolution operations with the receiver subsystem model.

4. The method defined in claim 1, wherein the link subsystems of each communications link comprise a channel subsystem that is represented by a channel subsystem model in the link simulation tool and wherein performing the two-dimensional convolution operations comprises performing two-dimensional convolution operations with the channel subsystem model.

5. The method defined in claim 1, wherein the link subsystems of each communications link comprise transmitter and receiver subsystems that are respectively represented by transmitter and receiver subsystem models in the link simulation tool and wherein performing the two-dimensional convolution operations comprises performing the two-dimensional convolution operations with the transmitter and receiver subsystem models.

6. The method defined in claim 5, wherein the transmitter and receiver subsystems of each communications link comprise transmitter and receiver subsystem components each of which is represented by a respective one of a plurality of characteristic functions, the method further comprising:

performing two-dimensional convolution operations on the characteristic functions.

7. The method defined in claim 6, wherein the transmitter subsystem components of each communications link comprise components selected from a first group consisting of:

a first equalizer, a first phase-locked loop, a first oscillator, and a driver and wherein the receiver subsystem components comprise components selected from a second group consisting of;

a buffer, a second equalizer, a second phase-locked loop, and a second oscillator.

8. The method defined in claim 7, wherein performing the two-dimensional convolution operations on the characteristic functions comprises:

convolving the characteristic functions of the first equalizer, the first phase-locked loop, the first oscillator, and the driver to produce the transmitter subsystem model; and

convolving the characteristic functions of the buffer, the second equalizer, the second phase-locked loop, and the second oscillator to produce the receiver subsystem model.

9. A method of simulating communications links using a link simulation tool that is implemented on computing equipment, comprising:

with the link simulation tool, displaying a timing diagram for transmitted signals having varying signal amplitudes at a given point in each of the communications links; and

with the link simulation tool, displaying a probability density function plot that represents a distribution of signal amplitude variations in the transmitted signals for each of the communications links.

10. The method defined in claim 9, wherein displaying the timing diagram comprises displaying an eye diagram of the transmitted signals for each of the communications links.

11. The method defined in claim 9, wherein displaying the probability density function plot comprises displaying a noise histogram plot for the transmitted signals for each of the communications links.

12. The method defined in claim 11 further comprising:

with the link simulation tool, displaying a jitter histogram plot for the transmitted signals for each of the communications links.

13. The method defined in claim 9 further comprising:

with the link simulation tool, displaying a three-dimensional bit error rate plot for the transmitted signals at the given point in each communications link.

14. The method defined in claim 13 further comprising:

with the link simulation tool, displaying cumulative density function plots associated with the bit error rate plot for each of the communications links, wherein the cumulative density function plots include a first cumulative density function plot that is a function of voltage and a second cumulative density function plot that is a function of time.

15. A method of simulating communications links using a link simulation tool implemented on computing equipment, comprising:

with the link simulation tool, providing a user with an opportunity to specify random jitter requirements for each of the communications links;

with the link simulation tool, providing the user with an opportunity to specify random noise requirements for each of the communications links; and

with the link simulation tool, producing simulation results for each of the communications links based on the random jitter and noise requirements specified by the user.

16. The method defined in claim 15 further comprising:

with the link simulation tool, providing the user with an opportunity to specify a data rate for each of the communications links.

17. The method defined in claim 15 further comprising:

with the link simulation tool, providing the user with an opportunity to specify a target bit error rate for each of the communications links.

18. The method defined in claim 17, wherein producing the simulation results comprises displaying jitter and noise cumulative density function plots that are based on the random jitter and noise requirements and the target bit error rate specified by the user for each of the communications links.

19. The method defined in claim 15, wherein producing the simulation results comprises displaying jitter and noise probability density function plots that are based on the random jitter and noise requirements specified by the user for each of the communications links.

20. Software on a computer-readable storage media for simulating performance in communications links, comprising:

code for providing a user with an opportunity to specify link simulation settings for the communications links;

code for performing two-dimension convolution operations to simulate performance in the communications links; and

code for displaying simulation results for each of the communications links produced by performing the two-dimensional convolution operations.