Method, system and apparatus for quantifying the contribution of inter-symbol interference jitter on timing skew budget

• US 7,889,785 B2
• Filed: 07/30/2007
• Issued: 02/15/2011
• Est. Priority Date: 12/05/2003
• Status: Active Grant

• Current Assignee: Dell Products LP (Dell Technologies Inc.)
• Original Assignee: Dell Products LP (Dell Technologies Inc.)
• Inventors: Greim, Michael, Murugan, Rajen
• Primary Examiner(s): Bayard; Emmanuel
• Application Number:
  US11/830,836
• Publication Number:
  US 20090034665A1
• Time in Patent Office: 1,296 Days
• Field of Search: 375/346, 375/348, 375/284, 375/286, 375/278, 375/230
• US Class Current: 375/230
• CPC Class Codes: G01R 31/31709 Jitter measurements; Jitter generators measuring jitter, noise figure or signal-to-noise ratio per se G01R29/26; analysis of tester signals G01R31/31901
• CPC Class Codes: G01R 31/31715 Testing of input or output circuits; test of circuitry between the I/C pins and the functional core, e.g. testing of input or output driver, receiver, buffer
• CPC Class Codes: G01R 31/31725 Timing aspects, e.g. clock distribution, skew, propagation delay for tester hardware G01R31/31937
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 7/0054 Detection of the synchronisation error by features other than the received signal transition by means of signal transition H04L7/033
• CPC Class Codes: H04L 7/10 Arrangements for initial synchronisation

Abstract

An apparatus, method and system are provided for quantifying communication channel intersymbol interference jitter effect contribution to timing skew. In general, lossy and lossless characteristics of the communication channel are preferably obtained and an output signal of the communication channel is sampled. From the sampled output signal and the lossy characteristics of the communication channel, an input signal may be derived. Using the lossless characteristics of the communication channel, the derived input signal and the sampled output signal, a value indicating the contribution of intersymbol interference jitter effect on timing skew budget for a selection communication channel may be obtained.

Claims

1. A method for analyzing the effect of inter-symbol interference (ISI) jitter in a communication channel, comprising:

determining a communication channel impulse response function from an impulse input function sent across the communication channel;

sampling an output signal from a normal operational signal sent across the communication channel; and

determining an effect of ISI jitter in the communication channel based at least on the impulse response function and the sampled output signal.

2. The method of claim 1, further comprising:

deriving an input signal to the communication channel based at least on the impulse response function and the sampled output signal; and

wherein determining an ISI jitter effect contribution to timing skew includes calculating a difference between a time of arrival for the derived input signal and the sampled output signal.

3. The method of claim 2, further comprising deriving the input signal to the communication channel by solving the equation

4. The method of claim 1, wherein the impulse input function comprises a DIRAC impulse input function.

5. The method of claim 1, further comprising:

determining a time of flight for the communication channel representing the time for a signal to travel across the communication channel under substantially lossless conditions; and

using the determined time of flight for determining the ISI jitter effect contribution to timing skew.

6. The method of claim 5, wherein determining the time of flight for the communication channel comprises sending a low frequency training pattern across the communication channel via idle insertion/deletion.

7. A method for analyzing the effect of inter-symbol interference (ISI) jitter in a communication channel, comprising:

determining a time of flight for the communication channel representing the time for a signal to travel across the communication channel under substantially lossless conditions;

determining an effect of ISI jitter in the communication channel based at least on the time of flight for the communication channel under substantially lossless conditions.

8. The method of claim 7, further comprising:

sampling an output signal from a normal operational signal sent across the communication channel; and

determining the ISI jitter effect contribution to timing skew based at least on the time of flight for the communication channel under substantially lossless conditions and the sampled output signal.

9. The method of claim 8, further comprising:

deriving an input signal to the communication channel based at least on the sampled output signal; and

wherein determining an ISI jitter effect contribution to timing skew includes calculating a difference between a time of arrival for the derived input signal and the sampled output signal.

10. The method of claim 7, further comprising:

determining a communication channel impulse response function from an impulse input function sent across the communication channel; and

determining the ISI jitter effect contribution to timing skew based at least on the time of flight for the communication channel under substantially lossless conditions and the communication channel impulse response function.

11. The method of claim 10, further comprising:

deriving an input signal to the communication channel based at least on the communication channel impulse response function; and

determining the ISI jitter effect contribution to timing skew based at least on the time of flight for the communication channel under substantially lossless conditions, the sampled output signal, and the derived input signal.

12. The method of claim 11, wherein determining the time of flight for the communication channel comprises sending a low frequency training pattern across the communication channel.

13. The method of claim 7, further comprising:

determining the lossyness of the communication channel;

deriving an input signal to the communication channel based at least on the determined lossyness of the communication channel; and

wherein determining an ISI jitter effect contribution to timing skew includes calculating a difference between a time of arrival for the derived input signal and the sampled output signal.

14. The method of claim 7, comprising determining the time of flight for the communication channel based at least on the length, capacitance and inductance of the communication channel.

15. The method of claim 14, further comprising obtaining data for the length, capacitance and inductance of the communication channel from a registry associated with the communication channel.

16. A method for analyzing the effect of inter-symbol interference (ISI) jitter in a communication channel, comprising:

sampling an output signal sent across a communication channel;

deriving an input signal to the communication channel based at least on the sampled output signal; and

calculating a difference between a time of arrival for the derived input signal and the sampled output signal to determine an effect of ISI jitter in the communication channel.

17. The method of claim 16, wherein sampling an output signal sent across a communication channel comprises an output signal from a normal operational signal sent across the communication channel.

18. The method of claim 16, further comprising:

determining a communication channel impulse response function from an impulse input function sent across the communication channel; and

deriving the input signal to the communication channel based at least on the sampled output signal and the communication channel impulse response function.

19. The method of claim 18, further comprising deriving the input signal to the communication channel by solving the equation

20. The method of claim 16, further comprising:

determining the lossyness of the communication channel; and

deriving the input signal to the communication channel based at least on the sampled output signal and the determined lossyness of the communication channel.