Scan structure for improving transition fault coverage and scan diagnostics
Stuck-at fault scan chain diagnostic method Patent #: 7010735
ApplicationNo. 10771218 filed on 02/03/2004
US Classes:702/117, Of circuit712/16Array processor operation
ExaminersPrimary: Raymond, Edward
Attorney, Agent or Firm
International ClassG06F 19/00
AbstractA mechanism for diagnosing broken scan chains based on leakage light emission is provided. An image capture mechanism detects light emission from leakage current in complementary metal oxide semiconductor (CMOS) devices. The diagnosis mechanism identifies devices with unexpected light emission. An unexpected amount of light emission may indicate that a transistor is turned off when it should be turned on or vice versa. All possible inputs may be tested to determine whether a problem exists with transistors in latches or with transistors in clock buffers. Broken points in the scan chain may then be determined based on the locations of unexpected light emission.