Method and apparatus for adaptively learning test error sources to reduce the total number of test measurements required in real-time

• US 6,324,486 B1
• Filed: 03/01/1999
• Issued: 11/27/2001
• Est. Priority Date: 03/01/1999
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Crook, David T., Williamson, Eddie L., List, Steven K., Rozum, Stephen P.
• Primary Examiner(s): Wachsman, Hal
• Assistant Examiner(s): PRETLOW, DEMETRIUS R
• Application Number:
  US09/259,609
• Time in Patent Office: 1,002 Days
• Field of Search: 702/117, 324/537, 324/555, 700/95, 700/109, 700/108
• US Class Current: 702/117
• CPC Class Codes: G01R 31/2834 Automated test systems [ATE]; using microprocessors or computers G01R31/317 takes precedence; ATE for detection of defective computer hardware G06F11/2736
• CPC Class Codes: G06F 11/2273 Test methods

Abstract

A method and system is presented for optimizing the number of required measurements to obtain in real-time by an automated tester that tests a device under test. During a test run, historical measurements are obtained and tracked. Each subsequent iteration the test attempts to re-measure the fewest number of measurements in real-time to obtain an accurate reflection of whether the device being tested passes or fails based on the real-time measurements and substituting historical measurements for those required measurements that were not taken in real-time.

Claims

1. A method for adaptively learning a set of real-time measurements to obtain in real-time during execution of an automated test, said method comprising the steps of:

measuring a current set of real-time measurements in real-time, said current set of real-time measurements comprising a subset of a full set of required measurements, each of said full set of required measurements being required to determine whether said test passed or failed;

obtaining a current set of historical measurements, said current set of historical measurements comprising corresponding historical measurement values for each of said required measurements that are not included in said current set of real-time measurements;

determining whether said test passed or failed based on said measured real-time measurements and said current set of historical measurements substituted for those required measurements that are not included in said current set of real-time measurements;

if said test fails;

choosing a current retry set of real-time measurements, said current retry set of real-time measurements comprising a subset of said required measurements different than said current set of real-time measurements;

measuring said current retry set of real-time measurements in real-time

obtaining a current retry set of historical measurements, said current retry set of historical measurements comprising corresponding historical measurement values for each of said required measurements that are not included in said current retry set of real-time measurements; and

redetermining whether said test passed or failed based on said current retry set of real-time measurements and said current retry set of historical measurements.

2. A method in accordance with claim 1, wherein:

said current retry set of real-time measurements comprises said full set of real-time measurements.

3. A method in accordance with claim 1, wherein:

if said test fails after said redetermining step;

choosing a next retry set of real-time measurements; and

repeating said second measuring step through said redetermining step using said next retry set of real-time measurements as said current retry set of real-time measurements.

4. A method in accordance with claim 3, wherein:

repeating said second measuring step, said second obtaining step, said redetermining step, said second choosing step, and said repeating step until said test passes or said current retry set of real-time measurements comprises said full set of required measurements.

5. A method in accordance with claim 1, wherein:

if said test passes after said redetermining step;

updating said corresponding historical measurement values of each of said current retry set of real-time measurements with said corresponding measured real-time measurements.

6. A method in accordance with claim 1, wherein:

if said test passes after said redetermining step;

setting said current set of real-time measurements to said current retry set of real-time measurements.

7. A method in accordance with claim 1, wherein:

if said test passes after said redetermining step;

determining a new set of real-time measurements; and

setting said current set of real-time measurements to said new set of real-time measurements.

8. A method in accordance with claim 7, wherein:

said determining step comprises;

selecting a reduced set of real-time measurements that result in said test passing, said reduced set of real-time measurements comprising a subset of said full set of required measurements.

9. A method in accordance with claim 8, wherein:

said selecting step comprises;

selecting a current reduced set of real-time measurements, said current reduced set of real-time measurements comprising a subset of said full set of required measurements;

measuring said current reduced set of real-time measurements in real-time;

obtaining a current set of historical measurements, said current set of historical measurements comprising corresponding historical measurement values for each of said required measurements that are not included in said current reduced set of real-time measurements;

determining whether said test passed or failed based on said measured reduced set of real-time measurements and said current set of historical measurements substituted for those required measurements that are not included in said current reduced set of real-time measurements;

if said test fails;

choosing a different reduced set of real-time measurements, said different reduced set of real-time measurements comprising a subset of said required measurements different that said current reduced set of real-time measurements;

substituting said current reduced set of real-time measurements with said different reduced set of real-time measurements;

repeating said measuring step through said determining step; and

if said test passes;

replacing said current set of real-time measurements with said current reduced set of real-time measurements.

10. A method in accordance with claim 1, wherein:

periodically updating said current set of real-time measurements with a newly determined current set of real-time measurements.

11. A method in accordance with claim 10, wherein said updating step comprises:

selecting a current reduced set of real-time measurements, said current reduced set of real-time measurements comprising a subset of said full set of required measurements;

measuring said current reduced set of real-time measurements in real-time;

obtaining a current set of historical measurements, said current set of historical measurements comprising corresponding historical measurement values for each of said required measurements that are not included in said current reduced set of real-time measurements;

determining whether said test passed or failed based on said measured reduced set of real-time measurements and said current set of historical measurements substituted for those required measurements that are not included in said current reduced set of real-time measurements;

if said test fails;

choosing a different reduced set of real-time measurements, said different reduced set of real-time measurements comprising a subset of said required measurements different that said current reduced set of real-time measurements;

substituting said current reduced set of real-time measurements with said different reduced set of real-time measurements;

repeating said measuring step through said determining step; and

if said test passes;

replacing said current set of real-time measurements with said current reduced set of real-time measurements.

12. A method for determining a reduced set of measurements to take in real-time when executing an automated test, said method comprising the steps of:

selecting a current reduced set of real-time measurements, said current reduced set of real-time measurements comprising a subset of a full set of required measurements, each of said full set of required measurements being required to determine whether said test passed or failed;

measuring said current reduced set of real-time measurements in real-time;

obtaining a current set of historical measurements, said current set of historical measurements comprising corresponding historical measurement values for each of said required measurements that are not included in said current reduced set of real-time measurements;

determining whether said test passed or failed based on said measured reduced set of real-time measurements and said current set of historical measurements substituted for those required measurements that are not included in said current reduced set of real-time measurements;

if said test fails;

choosing a different reduced set of real-time measurements, said different reduced set of real-time measurements comprising a subset of said required measurements different that said current reduced set of real-time measurements;

substituting said current reduced set of real-time measurements with said different reduced set of real-time measurements;

repeating said measuring step through said determining step; and

if said test passes;

using said current reduced set of real-time measurements as said reduced set of measurements to take in real-time when executing said automated test.

13. An automated testing system for testing a component under test, comprising:

a test configuration circuit that connects to said component under test and obtains a current set of real-time measurements; and

a results analyzer which calculates a component value for said component under test using said current set of real-time measurements and substituting historical values for any required measurements that are not included in said real-time time measurements, determines whether said component value is within a pre-determined test limits, and signals a retry if said calculated component value is not within said pre-determined test limits;

a measurement combination processor which is responsive to said retry signal to select a current retry set of real-time measurements;

wherein said test configuration circuit obtains said current retry set of real-time measurements from said component under test and said results analyzer calculates a component value for said component under test using said current retry set of real-time measurements and substituting historical values for any required measurements that are not included in said current retry set of real-time measurements, and determines whether said component value is within said pre-determined test limits.

14. A system in accordance with claim 13, wherein:

if said calculated component value is not within said pre-determined test limits and said current set of real-time measurements does not comprise each of said required measurements, said measurement combination processor selects a next retry set of real-time measurements.

15. A system in accordance with claim 13, comprising:

a table comprising a plurality of subsets of said required measurements, each subset having an associated priority defining the order in which to use the subset as said current set of real-time measurements.

16. A system in accordance with claim 15, wherein:

said measurement combination processor selects a subset from said table, in order of said defined priority, as said current set of real-time measurements.

17. A system in accordance with claim 13, wherein:

said current set of real-time measurements comprises a fewest number of said required measurements which, when said historical values are substituted for any of said required measurements that are not included in said current set of real-time measurements, results in an accurate reflection of whether said calculated component value is within said pre-determined test limits; and

said current retry set of real-time measurements comprises a next fewest number of said required measurements which, when said historical values are substituted for any of said required measurements that are not included in said current retry set of real-time measurements, results in an accurate reflection of whether said calculated component value is within said pre-determined test limits.

18. A system in accordance with claim 13, wherein:

said current retry set of real-time measurements comprises all of said required measurements.

19. A system in accordance with claim 13, comprising:

an audit function which periodically remeasures at least one of said required measurements in real-time and replaces said historical values with said corresponding remeasured required measurements.

20. A system in accordance with claim 19, wherein:

said audit function is performed after a pre-determined number of passing tests.