Device and Method for Diagnosis of the Same

The device of clam 1, wherein:

• the diagnostic hardware circuit is configured to diagnose a stuck-at-1 fault in one or more sequential elements of the scan chain during the diagnostic mode;
• a test pattern data includes a sequence of logical lows is serially shifted through the scan chain;
• the expected output pattern is compared with the actual output pattern at the output terminal;
• and
• a discrepancy between the expected and actual output patterns indicates the presence of a stuck-at-1 fault in one or more sequential elements.

A device configured to operate in functional and diagnostic modes, the device comprising:

• an input terminal configured to receive test pattern data;
• an output terminal configured to provide diagnostic output data;
• a bi-directional scan chain connected between the input terminal and the output terminal, the bi-directional scan chain including:
• a plurality of sequential elements connected in series and grouped into a plurality of segments, wherein the plurality of segments include a first segment and a second segment that follows the first segment;
• and
• a diagnostic hardware circuit including:
• a plurality of circuit components, each connected to one sequential element of a respective segment;
• and
• a feedback loop connecting an output of the second segment to an input of the first segment, wherein the diagnostic hardware circuit is configured to perform:
• a forward-shift diagnosis to propagate the test pattern data from a first sequential element to a last sequential element of the scan chain to identify a defective segment of the scan chain during the diagnostic mode;
• and
• a backward-shift diagnosis to propagate the test pattern data from the last sequential element to the first sequential element to isolate the faulty sequential element of the defective segment during the diagnostic mode;
• and
• a device circuit connected to the scan chain and configured to perform one or more circuit functions and to generate functional data that is sequentially shifted through the scan chain during the functional mode.

The device of clam 8, wherein:

• the forward-shift diagnosis is configured to identify a defective segment of the scan chain;
• a test pattern data is serially shifted from the first sequential element to the last sequential element of the scan chain;
• the output terminal captures the resulting response of the scan chain;
• the expected output pattern is compared with the actual output pattern to detect a discrepancy;
• and
• a defective segment is identified when the discrepancy indicates a deviation from the expected propagation of the test pattern data through the scan chain.

A method for diagnosing faults in a device, the method comprising:

• performing a coarse-grain diagnosis on a scan chain of the device to identify a defective segment, wherein the scan chain includes:
• a plurality of sequential elements grouped into segments;
• and
• a diagnostic hardware circuit including a plurality of circuit components, each connected to a first sequential element of a respective segment;
• and
• performing a fine-grain diagnosis on the identified defective segment to pinpoint one or more faulty sequential elements of the defective segment by serially shifting test pattern data through the scan chain.