Compressing test responses using a compactor

• US 7,743,302 B2
• Filed: 01/30/2008
• Issued: 06/22/2010
• Est. Priority Date: 02/13/2003
• Status: Active Grant

• Current Assignee: Siemens Industry Software Limited (Siemens AG)
• Original Assignee: Mentor Graphics Corporation (Siemens AG)
• Inventors: Pogiel, Artur, Wang, Chen, Mrugalski, Grzegorz, Tyszer, Jerzy, Rajski, Janusz
• Primary Examiner(s): BRITT, CYNTHIA H
• Application Number:
  US12/012,039
• Publication Number:
  US 20080133987A1
• Time in Patent Office: 874 Days
• Field of Search: 714726-729, 714731-734
• US Class Current: 714/734
• CPC Class Codes: G01R 31/31703 Comparison aspects, e.g. signature analysis, comparators concerning scan tests G01R31/318566; concerning testers G01R31/3193
• CPC Class Codes: G01R 31/318536 Scan chain arrangements, e.g. connections, test bus, analog signals
• CPC Class Codes: G01R 31/318566 Comparators; Diagnosing the device under test
• CPC Class Codes: G01R 31/318583 Design for test
• CPC Class Codes: G01R 31/31921 using compression techniques, e.g. patterns sequencer
• CPC Class Codes: G11C 2029/3202 Scan chain
• CPC Class Codes: G11C 29/40 using compression techniques
• CPC Class Codes: G11C 29/48 Arrangements in static stores specially adapted for testing by means external to the store, e.g. using direct memory access [DMA] or using auxiliary access paths

Abstract

The present disclosure describes embodiments of a compactor for compressing test results in an integrated circuit and methods for using and designing such embodiments. The disclosed compactors can be utilized, for example, as part of any scan-based design. Moreover, any of the disclosed compactors can be designed, simulated, and/or verified in a computer-executed application, such as an electronic-design-automation (“EDA”) software tool. Embodiments of a method for diagnosing faults in the disclosed compactor embodiments are also described.

Claims

1. An apparatus for compressing test responses in an integrated circuit, comprising:

a plurality of memory elements; and

an injector network comprising combinational logic, the injector network having injector-network outputs and injector-network inputs,

each injector-network output being coupled to a respective one of the memory elements,

each injector-network input being logically coupled to two or more injector-network outputs according to a respective injector polynomial, the respective injector polynomial being selected to prevent one, two, and odd-numbered error masking in the memory elements.

2. The apparatus of claim 1, wherein two or more of the memory elements are further coupled in series via feedback-free logic.

3. The apparatus of claim 2, wherein the feedback-free logic is configured to combine serially shifted values from the two or more memory elements with respective values from the injector-network outputs.

4. The apparatus of claim 1, wherein the two or more memory elements are configured to output a series of output values over a fixed period of clock cycles, and wherein the series of output values is associated with a test value.

5. The apparatus of claim 1, wherein the plurality of memory elements are serially connected to one another via logic that includes at least one feedback loop.

6. The apparatus of claim 1, wherein the plurality of memory elements form a multiple input signature register (MISR).

7. The apparatus of claim 6, wherein the injector network prevents MISR cancellation in the MISR when two errors are injected during a same cycle and reduces MISR cancellation when other even-numbered errors are injected during the same cycle.

8. The apparatus of claim 1, further comprising a bypass network coupled between the injector-network inputs and scan-chain outputs.

9. The apparatus of claim 1, further comprising a selector circuit coupled between the injector-network inputs and scan-chain outputs, the selector circuit being operable to mask one or more of the scan-chain outputs.

10. The apparatus of claim 1, further comprising at least one serial-input-parallel-output register coupled between at least one scan-chain and two or more of the injector-network inputs.

11. The apparatus of claim 1, further comprising at least one scan chain having multiple outputs coupled to one or more of the injector-network inputs.

12. The apparatus of claim 1, further comprising means for diagnosing output values output from the plurality of memory elements.

13. A computer-readable medium storing computer-executable instructions for causing a computer system to design an apparatus, the apparatus comprising:

a plurality of memory elements; and

an injector network comprising combinational logic, the injector network having injector-network outputs and injector-network inputs,

each injector-network output being coupled to a respective one of the memory elements,

each injector-network input being logically coupled to two or more injector-network outputs according to a respective injector polynomial, the respective injector polynomial being selected to prevent one, two, and odd-numbered error masking in the memory elements.

14. The computer-readable medium of claim 13, wherein two or more of the memory elements of the apparatus are further coupled in series via feedback-free logic.

15. The computer-readable medium of claim 13, wherein the two or more memory elements of the apparatus are configured to output a series of output values over a fixed period of clock cycle, and wherein the series of output values is associated with a test value.

16. The computer-readable medium of claim 13, wherein the plurality of memory elements of the apparatus are serially connected to one another via logic that includes at least one feedback loop.

17. The computer-readable medium of claim 13, wherein the plurality of memory elements of the apparatus form a multiple input signature register (MISR).

18. The computer-readable medium of claim 13, wherein the apparatus further comprises a bypass network coupled between the injector-network inputs and scan-chain outputs.

19. The computer-readable medium of claim 13, wherein the apparatus further comprises a selector circuit coupled between the injector-network inputs and scan-chain outputs, the selector circuit being operable to mask one or more of the scan-chain outputs.

20. The computer-readable medium of claim 13, wherein the apparatus further comprises at least one serial-input-parallel-output register coupled between at least one scan-chain and two or more of the injector-network inputs.

21. The computer-readable medium of claim 13, wherein the apparatus further comprises at least one scan chain having multiple outputs coupled to one or more of the injector-network inputs.

22. A computer-readable medium storing a design database that includes design information for an apparatus, the apparatus comprising:

a plurality of memory elements; and

an injector network comprising combinational logic, the injector network having injector-network outputs and injector-network inputs,

each injector-network output being coupled to a respective one of the memory elements,

each injector-network input being logically coupled to two or more injector-network outputs according to a respective injector polynomial, the respective injector polynomial being selected to prevent one, two, and odd-numbered error masking in the memory elements.

23. The computer-readable medium of claim 22, wherein two or more of the memory elements of the apparatus are further coupled in series via feedback-free logic.

24. The computer-readable medium of claim 22, wherein the two or more memory elements of the apparatus are configured to output a series of output values over a fixed period of clock cycle, and wherein the series of output values is associated with a test value.

25. The computer-readable medium of claim 22, wherein the plurality of memory elements of the apparatus are serially connected to one another via logic that includes at least one feedback loop.

26. The computer-readable medium of claim 22, wherein the plurality of memory elements of the apparatus form a multiple input signature register (MISR).

27. The computer-readable medium of claim 22, wherein the apparatus further comprises a bypass network coupled between the injector-network inputs and scan-chain outputs.

28. The computer-readable medium of claim 22, wherein the apparatus further comprises a selector circuit coupled between the injector-network inputs and scan-chain outputs, the selector circuit being operable to mask one or more of the scan-chain outputs.

29. The computer-readable medium of claim 22, wherein the apparatus further comprises at least one serial-input-parallel-output register coupled between at least one scan-chain and two or more of the injector-network inputs.

30. The computer-readable medium of claim 22, wherein the apparatus further comprises at least one scan chain having multiple outputs coupled to one or more of the injector-network inputs.