TUNING A TESTING APPARATUS FOR MEASURING SKEW

• US 20170023629A1
• Filed: 07/20/2015
• Published: 01/26/2017
• Est. Priority Date: 07/20/2015
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: BERGE, Layne A., FOX, Benjamin A., MARTIN, Wesley D., SILJENBERG, David W., ZETTLES, George R. IV
• Granted Patent: US 10,684,319 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01R 31/11 using pulse reflection methods
• 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 31/31725 Timing aspects, e.g. clock distribution, skew, propagation delay for tester hardware G01R31/31937
• CPC Class Codes: G01R 31/31727 Clock circuits aspects, e.g. test clock circuit details, timing aspects for signal generation, circuits for testing clocks G01R31/31725 takes precedence; concerning scan test G01R31/318552, for tester hardware G01R31/31922
• CPC Class Codes: G01R 31/31905 Interface with the device under test [DUT], e.g. arrangements between the test head and the DUT, mechanical aspects, fixture
• CPC Class Codes: G01R 31/3191 Calibration
• CPC Class Codes: G01R 31/31937 Timing aspects, e.g. measuring propagation delay G01R31/3191 and G01R31/31922 take precedence; marginal testing G06F11/24

Abstract

Embodiments herein discuss tuning a testing apparatus to better match the input response of a target system in which a cable will be used. For example, conductors in the cable may have a different skew depending on the system in which they are used. The testing apparatus may be tuned using frequency information regarding the type of signals that will be driven on the cable when installed in the target system. In one embodiment, the testing apparatus adjusts a testing cycle refresh rate for generating a testing signal which changes the frequency content of the testing signal. Using the adjusted testing cycle refresh rate results in the driver outputting a testing signal that better reflects the actual signals that will be transmitted on the cable in the target system.

Claims

1. A method comprising:

adjusting a testing cycle refresh rate for generating a testing signal, wherein adjusting the testing cycle refresh rate changes the frequency content of the testing signal;

driving the testing signal using the adjusted testing cycle refresh rate onto a plurality of conductors; and

measuring skew associated with the plurality of conductors in response to driving the testing signal.

2. The method of claim 1, further comprising:

receiving frequency information associated with a target computing system in which the plurality of conductors are intended to be used.

4. The method of claim 1, wherein the plurality of conductors is disposed in a cable.

5. The method of claim 1, further comprising:

configuring a programmable clock source, wherein each configuration of the clock source corresponds to a respective frequency response different form frequency responses of other configurations of the clock source; and

generating the testing signal using an output of the configured clock source and the adjusted testing cycle refresh rate.

6. The method of claim 1, wherein the driving and measuring are performed using a time domain reflectometer (TDR).

7. The method of claim 1, wherein the adjusting the testing cycle refresh rate comprises:

selecting one or more clock edges; and

selecting a frequency at which the clock edges repeat to generate sequential testing cycles.

3. The method of claim 3, wherein the testing cycle refresh rate is adjusted based on a similarity between the frequency information associated with the target computing system and the frequency content in the testing signal generated using the adjusted testing cycle refresh rate.

8. A testing apparatus, comprising:

logic configured to adjust a testing cycle refresh rate for generating a testing signal, wherein adjusting the testing cycle refresh rate changes the frequency content of the testing signal;

a driver configured to drive the testing signal generated using the adjusted testing cycle refresh rate onto a plurality of conductors; and

a skew calculator configured to measure skew associated with the plurality of conductors in response to driving the testing signal.

9. The testing apparatus of claim 8, wherein the logic is further configured to adjust the testing cycle refresh rate based on receiving frequency information associated with a target computing system in which the plurality of conductors are intended to be used.

10. The testing apparatus of claim 9, wherein the clock adjustor is further configured to adjust the testing cycle refresh rate based on a similarity between the frequency information associated with the target computing system and the frequency content in the testing signal generated using the adjusted testing cycle refresh rate.

11. The testing apparatus of claim 8, further comprising:

a first port configured to connect to a first conductor of the plurality of conductors; and

a second port configured to connect to a second conductor of the plurality of conductors.

12. The testing apparatus of claim 8, further comprising a TDR.

13. The testing apparatus of claim 12, further comprising a pluggable TDR head in the TDR, wherein the driver and the logic are disposed in the TDR head.

14. The testing apparatus of claim 8, wherein the logic is configured to adjust the testing cycle refresh rate by:

selecting one or more clock edges, and

selecting a frequency at which the clock edges repeat to generate sequential testing cycles.

16. The computer program product of claim 11, wherein the computer-readable program code is further executable to:

receive frequency information associated with a target computing system in which the plurality of conductors are intended to be used.

15. A computer program product for testing a plurality of conductors, the computer program product comprising:

a computer-readable storage medium having computer-readable program code embodied therewith, the computer-readable program code executable by one or more computer processors to;

adjust a testing cycle refresh rate for generating a testing signal, wherein adjusting the testing cycle refresh rate changes the frequency content of the testing signal;

drive the testing signal using the adjusted testing cycle refresh rate onto the plurality of conductors; and

measure skew associated with the plurality of conductors in response to driving the testing signal.

17. The computer program product of claim 15, wherein the testing cycle refresh rate is adjusted based on a similarity between the frequency information associated with the target computing system and the frequency content in the testing signal generated using the adjusted testing cycle refresh rate.

18. The computer program product of claim 15, wherein the plurality of conductors is disposed in a cable.

19. The computer program product of claim 15, wherein the adjusting the testing cycle refresh rate comprises computer-readable program code is further executable to:

select one or more clock edges; and

select a frequency at which the clock edges repeat to generate sequential testing cycles.

20. The computer program product of claim 15, wherein the driving the testing signal and measuring the skew are performed by a TDR.