Compacting circuit responses

• US 20060036985A1
• Filed: 10/17/2005
• Published: 02/16/2006
• Est. Priority Date: 03/27/2002
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Numonyx BV (Micron Technology, Inc.)
• Inventors: Mitra, Subhasish, Kim, Kee Sup
• Granted Patent: US 7,814,383 B2
• Time in Patent Office: Days
• US Class Current: 716/118
• CPC Class Codes: G01R 31/3172 Optimisation aspects, e.g. using functional pin as test pin, pin multiplexing
• CPC Class Codes: G01R 31/318547 Data generators or compressors
• CPC Class Codes: G01R 31/318566 Comparators; Diagnosing the device under test

Abstract

Circuit responses to a stimulus may be compacted, decreasing the number of pin outs, without increasing the circuit element length, using a compactor. In accordance with one embodiment of the present invention, errors may be detected in scan chains used for integrated circuit testing. The number of outputs applied to output pins or other connectors may be substantially decreased, resulting in cost savings.

Claims

1. A method comprising:

forming a response compactor with a plurality of inputs and a plurality of outputs; and

coupling said inputs to said outputs such that every input is coupled to a unique set of at least two outputs.

2. The method of claim 1 including coupling each input to more than two outputs.

3. The method of claim 2 including coupling each input to multiple outputs so that any time an unknown value is received at an input, there are other connections to the output not covered by said unknown value.

4. The method of claim 1 including coupling each input to a different set of outputs than any other input.

5. The method of claim 1 including coupling each input to a plurality of outputs and each input to a different set of outputs than any other of said inputs.

6. The method of claim 1 including forming a compactor whose inputs are scan chains.

7. The method of claim 1 including forming fewer outputs than inputs.

8. The method of claim 1 including forming alternate input to output paths that do not collide with any unknown values received at an input.

9. A response compactor comprising:

a plurality of inputs and a plurality of outputs; and

said inputs coupled to said outputs such that every input is coupled to a unique set of at least two outputs.

10. The compactor of claim 9 wherein each input is coupled to more than two outputs.

11. The compactor of claim 10 wherein each input is coupled to multiple outputs so that any time an unknown value is received in an input, there are other connections to the output not covered by said unknown value.

12. The compactor of claim 9 wherein each input is coupled to a different set of outputs than any other input.

13. The compactor of claim 9 wherein each input is coupled to a plurality of outputs and each input is coupled to a different set of outputs than any other of said inputs.

14. The compactor of claim 9 wherein said inputs are scan chains.

15. The compactor of claim 9 including fewer outputs than inputs.

16. The compactor of claim 9 including alternate input to output paths that do not collide with any unknown values received at an input.