The disclosure describes novel methods and apparatuses for controlling a device's TCA circuit when the device exists in a JTAG daisy-chain arrangement with other devices. The methods and apparatuses allow the TCA test pattern set used during device manufacturing to be reused when the device is placed in a JTAG daisy-chain arrangement with other devices, such as in a customers system using the device. Additional embodiments are also provided and described in the disclosure.

Electronic scan circuitry includes a decompressor (510), a plurality of scan chains (520.i) fed by the decompressor (510), a scan circuit (502, 504) coupled to the plurality of scan chains (520.i) to scan them in and out, a masking circuit (590) fed by the scan chains (520.i), and a scannable masking qualification circuit (550, 560, 580) coupled to the masking circuit (590), the masking qualification circuit (550, 560, 580) scannable by scan-in of bits by the decompressor (510) along with scan-in of the scan chains (520.i), and the scannable masking qualification circuit (550, 560, 580) operable to hold such scanned-in bits upon scan-out of the scan chains through the masking circuit (590). Other scan circuitry, processes, circuits, devices and systems are also disclosed.

A system-on-chip includes a first scan register being in a first core and being closest to an input port of the first core; an inverting circuit on a feedback path of the first scan register; a second scan register in the first core; and a logic circuit on a data path between the first scan register and the second scan register. In a test mode for an AT-SPEED test of the logic circuit, the inverting circuit generates test data by inverting scan data that are output from the first scan register, the first scan register stores the test data in response to a first pulse of a clock signal, the logic circuit generates result data based on the test data that are output from the first scan register, and the second scan register stores the result data in response to a second pulse of the clock signal.

A test pattern is shifted into scan chains in a circuit in a first direction. The scan cells on each of the scan chains are further coupled to corresponding scan cells on two other scan chains in the scan chains such that data bits stored in the scan cells can be shifted circularly in a second direction orthogonal to the first direction based on a control signal. The loaded test pattern is then shifted in the second direction for a number of clock cycles equal to the number of the scan chains. The test pattern is then shifted in the first direction out of the scan chains to generate a chain test result. Faulty scan cell candidates on faulty scan chains may be determined based on part of the chain test result for one of good scan chains.

This application discloses a computing system implementing an automatic test pattern generation tool can generate test patterns to apply to a reversible scan chain in an integrated circuit. The reversible scan chain can be configured to serially load and unload the test patterns in multiple directions to generate test responses. The computing system can implement a defect diagnosis tool to detect a presence of a suspected defect associated with the reversible scan chain based on the test responses, identify which of the multiple directions used to load and unload the test patterns corresponds to the suspected defect in the reversible scan chain based on the test responses, and determine a portion of the integrated circuit to inspect for a manufacturing fault corresponding to the suspected defect based, at least in part, on the identification of which of the multiple directions corresponds to the suspected defect in the reversible scan chain.

Examples described herein provide a computer-implemented method that includes initiating a logic built-in self-test (LBIST) of a device under test (DUT). The method further includes performing latch state counting using a multiple input signature register (MISR) of the DUT, the performing responsive to the MISR being in a counter mode. The method further includes performing a latch transition counting of latches of the DUT using the MISR of the DUT and a storage latch, the performing responsive to the MISR being in the counter mode. The method further includes performing a latch count comparison by comparing an output of the MISR responsive to the MISR being in the counter mode to an output of a count compare register, the output of the count compare register representing a desired MISR state.

According to one embodiment, a semiconductor integrated circuit includes: a logic circuit including a first scan chain configured to operate based on a first clock signal and a second scan chain configured to operate based on a second clock signal in a built-in self-test; a pattern generator configured to generate a test pattern and transmit the test pattern to the first and second scan chains; a compression circuit configured to compress first data received from the first and second scan chains; a clock select circuit configured to select one of the first and second clock signals and transmit the one of the first and second clock signals to the corresponding one of the first and second scan chains in the test; and a test control circuit configured to control the test and detect a fault in the logic circuit based on a result of the test.

Examples described herein provide a computer-implemented method that includes initiating a logic built-in self-test (LBIST) of a device under test (DUT). The method further includes performing latch state counting using a multiple input signature register (MISR) of the DUT, the performing responsive to the MISR being in a counter mode. The method further includes performing a latch transition counting of latches of the DUT using the MISR of the DUT and a storage latch, the performing responsive to the MISR being in the counter mode. The method further includes performing a latch count comparison by comparing an output of the MISR responsive to the MISR being in the counter mode to an output of a count compare register, the output of the count compare register representing a desired MISR state.

A method for testing a many-core processor comprises grouping a plurality of cores in the processor into a plurality of super cores, wherein each super core comprises one or more scan chains that propagate through a respective super core. Further, the method comprises grouping the plurality of super cores into a plurality of clusters. The method also comprises comparing one or more scan chain outputs of respective super cores in each cluster using a network of XOR and OR gates to generate a single bit fault signature for each scan chain in a respective cluster and compacting the single bit fault signatures for each scan chain using a hybrid of spatial and temporal compactors to generate a single bit fault signature for each cluster. The method also comprises method of using a cost function to obtain hierarchical parameters to achieve optimized ATPG effort, area overhead and test time.

A circuit comprises: a bit-flipping signal generation device comprising a storage device and configured to generate a bit-flipping signal based on bit-flipping location information, the storage device configured to store the bit-flipping location information for a first number of bits, the bit-flipping location information obtained through a fault simulation process; a pseudo random test pattern generator configured to generate test patterns based on the bit-flipping signal, the pseudo random test pattern generator comprising a register configured to be a linear finite state machine, the register comprising storage elements and bit-flipping devices, each of the bit-flipping devices coupled to one of the storage elements; and scan chains configured to receive the test patterns, wherein the bit-flipping signal causes one of the bit-flipping devices to invert a bit of the register each time a second number of test patterns is being generated by the pseudo random test pattern generator during a test.