On-chip full eye viewer architecture

• US 8,451,883 B1
• Filed: 12/03/2009
• Issued: 05/28/2013
• Est. Priority Date: 12/03/2009
• Status: Active Grant

• Current Assignee: Altera Corporation (Intel Corporation)
• Original Assignee: Altera Corporation (Intel Corporation)
• Inventors: Ding, Weiqi, Pan, Mingde, Shumarayev, Sergey, Li, Peng
• Primary Examiner(s): Vo, Don N
• Application Number:
  US12/630,674
• Time in Patent Office: 1,272 Days
• Field of Search: 375/226, 375/228, 375/232, 375/316, 375/355
• US Class Current: 375/228
• CPC Class Codes: G01R 31/3171 BER [Bit Error Rate] test
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/203 Details of error rate determination, e.g. BER, FER or WER
• CPC Class Codes: H04L 1/205 jitter monitoring
• CPC Class Codes: H04L 1/248 Distortion measuring systems measurement of non-linear distortion G01R23/20; measuring characteristics of individual pulses, e.g. deviation from pulse flatness, rise time, duration G01R29/02
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop
• CPC Class Codes: H04L 7/0334 Processing of samples having at least three levels, e.g. soft decisions
• CPC Class Codes: H04L 7/048 using the properties of error detecting or error correcting codes, e.g. parity as synchronisation signal

Abstract

Systems, methods, and devices for determining an eye diagram of a serial input signal to an integrated circuit without an oscilloscope are provided. For example, one embodiment of an integrated circuit device may be capable of determining an eye diagram associated with an equalized serial input signal. The device may include an equalizer and eye viewer circuitry. The equalizer may receive and perform equalization on a serial input signal to produce the equalized serial input signal, and the eye viewer circuitry may determine horizontal and vertical boundaries of the eye diagram associated with the equalized serial input signal.

Claims

1. An integrated circuit device comprising:

internal circuitry configured to propagate an equalized serial signal based at least in part on a received serial input signal; and

eye viewer circuitry configured to determine horizontal and vertical boundaries of an eye diagram associated with the equalized serial signal, wherein the eye viewer circuitry is configured to determine the horizontal and vertical boundaries of the eye diagram by;

sampling the equalized serial signal at variable phase offsets from a clock signal associated with the equalized serial signal and at variable threshold voltages; and

testing an error rate associated with the sampled signal, wherein the error rate is determined based at least in part on;

known data of at least a subset of the received serial input signal;

a cyclic redundancy check (CRC) of the received serial signal;

or

a combination thereof.

2. The device of claim 1, wherein the equalized serial signal operates at between approximately 6 and 12 Gbps.

3. The device of claim 1, wherein the eye viewer circuitry is configured to determine the horizontal and vertical boundaries of the eye diagram when the device is operating in an eye viewer mode.

4. The device of claim 3, wherein the device is configured to enter the eye viewer mode when the eye viewer circuitry receives a control signal from an external device.

5. The device of claim 1, wherein the eye viewer circuitry is configured to output the error rate associated with horizontal and vertical locations of an eye of the equalized serial signal.

6. The device of claim 1, wherein the device is a programmable logic device.

7. The device of claim 1, wherein the subset of the received serial input signal comprises polarity bits of data within the received serial input signal.

8. An integrated circuit device comprising:

a phase interpolator configured to receive a clock signal and a phase control signal and shifting the phase of the clock signal based at least in part on the phase control signal to produce an offset clock signal;

a threshold variable comparator configured to receive an equalized serial input signal, the offset clock signal, and a threshold voltage control signal, and sampling the equalized serial input signal at the offset clock signal and at a threshold voltage indicated by the threshold voltage control signal to produce an offset data signal;

error checking circuitry configured to;

detect an error rate of the offset data signal, wherein the error rate is determined based at least in part on data contained in the offset data signal and known data contained in a serial input signal used to generate the equalized serial input signal; and

produce an error rate signal based at least in part on the error rate; and

control logic configured to receive the error rate signal and generate the phase control signal and the threshold voltage control signal to determine an eye diagram associated with the serial input signal based at least in part on the error rate indicated by the error rate signal.

9. The device of claim 8, comprising clock and data recovery circuitry configured to receive the equalized serial input signal and determining the clock signal based on the equalized serial input signal.

10. The device of claim 8, wherein the error checking circuitry is configured to detect a cyclic redundancy check error rate.

11. The device of claim 8, wherein the known data contained in the serial input signal includes priority bits of the serial input signal.

12. The device of claim 8, wherein the control logic is configured to determine vertical boundaries of the eye diagram by increasing or decreasing the threshold voltage indicated by the threshold voltage signal until the error rate exceeds a threshold.

13. The device of claim 8, wherein the control logic is configured to determine horizontal boundaries of the eye diagram by increasing or decreasing the phase control signal until the error rate exceeds a threshold.

14. The device of claim 8, wherein the control logic is configured to output signals representing horizontal and vertical coordinates of the eye diagram that correspond respectively to the offset clock signal and the threshold voltage received by the threshold variable comparator.

15. The device of claim 14, wherein the device is configured to output signals representing the error rate associated with the data contained in the offset data signal for each of the horizontal and vertical coordinates of the eye diagram.

16. A method comprising:

receiving a serial input signal into a receiver;

equalizing the received serial input signal;

sampling the equalized serial input signal at discrete horizontal and vertical positions of an eye of the received serial input signal using a threshold variable comparator;

determining an error rate associated with the sampled signal using error checking circuitry, wherein the error rate is determined based at least in part on;

known data of at least a subset of the received serial input signal;

a cyclic redundancy check (CRC) of the received serial signal;

or

a combination thereof; and

determining a boundary of the eye of the equalized serial input signal when the determined error rate exceeds a maximum acceptable error rate.

17. The method of claim 16, wherein sampling the equalized serial input signal comprises selecting a horizontal position of the eye of the received input signal and increasing or decreasing the vertical position until the boundary of the eye of the received signal is determined.

18. The method of claim 16, wherein sampling the equalized serial input signal comprises selecting a vertical position of the eye of the received input signal and increasing or decreasing the horizontal position until the boundary of the eye of the received signal is determined.

19. The method of claim 16, comprising repeating the steps of sampling the equalized serial input signal, determining the error rate of the sampled signal, and determining the boundary of the eye of the equalized serial input signal until all boundaries of the eye of the equalized serial input signal are determined.

20. The method of claim 16, wherein the maximum acceptable error rate is no greater than an optical fiber error rate.

21. A method comprising:

receiving a serial signal into a receiver;

performing equalization on the received serial signal using an equalizer;

sampling the equalized signal at variable phase offsets from a clock signal associated with the equalized signal and at variable threshold voltages using a threshold variable comparator;

detecting an error rate in the sampled signal using error checking circuitry, wherein the error rate is determined based at least in part on known data of at least a subset of the received serial signal; and

determining an eye diagram of the equalized signal based at least in part on the detected error rate using logic circuitry configured to control the threshold variable comparator.

22. The method of claim 21, comprising recovering the clock signal associated with the equalized signal using clock and data recovery circuitry.

23. The method of claim 21, comprising transmitting a signal, from an external device to the equalizer, configured to cause the equalizer to perform equalization on the received serial signal such that the eye diagram of the equalized signal is more open.

24. A method comprising:

receiving, into a processor, eye diagram coordinates from an integrated circuit device equalizing a serial input signal and having eye diagram circuitry configured to determine the eye diagram coordinates based at least in part on an error rate associated with data sampled from horizontal and vertical locations of an eye of the equalized serial input signal and known data of at least a subset of the serial input signal; and

constructing, using the processor, an eye diagram associated with the equalized serial input signal based at least in part on the received eye diagram coordinates.

25. The method of claim 24, wherein the constructed eye diagram is a two-dimensional eye diagram that indicates a horizontal and vertical shape of the eye of the equalized input signal.

26. The method of claim 24, comprising receiving, into the processor, the error rate associated with the data sampled from the horizontal and vertical locations of the eye of the equalized serial input signal and the known data of at least a subset of the serial input signal.

27. The method of claim 26, wherein the constructed eye diagram is a three-dimensional eye diagram that indicates the error rates associated with the horizontal and vertical locations of the eye of the equalized serial input signal.

28. The method of claim 27, wherein the constructed eye diagram indicates the error rates with colors or distances, or a combination thereof.

29. The method of claim 24, wherein equalizing the serial input signal is configured to cause the eye of the equalized serial input signal to become more open.