Abstract: Memory array built in self testing utilizing including a simple data history table. The table is used to track failing locations observed during any level of assembly test of processor or logic semiconductor chips where the chips contain SRAM macros with redundant elements for failure relief.

Abstract: Memory array built in self testing utilizing including a simple data history table. The table is used to track failing locations observed during any level of assembly test of processor or logic semiconductor chips where the chips contain SRAM macros with redundant elements for failure relief.

Abstract: In one aspect, an electronic device that has been partitioned into segments by using clock gating or signal gating is tested. One of the segments that is a source of a failure is identified. Diagnostic procedures are applied to the identified segment to determine a cause of the failure.

Abstract: A circuit for measuring timing uncertainty in a clocked digital path and in particular, the number of logic stages completed in any clock cycle. A local clock buffer receives a global clock and provides a complementary pair of local clocks. A first local (launch) clock is an input to a delay line, e.g., 3 clock cycles worth of series connected inverters. Delay line taps (inverter outputs) are inputs to a register that is clocked by the complementary clock pair to capture progression of the launch clock through the delay line and identify any variation (e.g., from jitter, VDD noise) in that progression. Global clock skew and across chip gate length variation can be measured by cross coupling launch clocks from a pair of such clock buffers and selectively passing the local and remote launch clocks to the respective delay lines.

Abstract: A circuit for measuring timing uncertainty in a clocked digital path and in particular, the number of logic stages completed in any clock cycle. A local clock buffer receives a global clock and provides a complementary pair of local clocks. A first local (launch) clock is an input to a delay line, e.g., 3 clock cycles worth of series connected inverters. Delay line taps (inverter outputs) are inputs to a register that is clocked by the complementary clock pair to capture progression of the launch clock through the delay line and identify any variation (e.g., from jitter, VDD noise) in that progression. Global clock skew and across chip gate length variation can be measured by cross coupling launch clocks from a pair of such clock buffers and selectively passing the local and remote launch clocks to the respective delay lines.

Abstract: A method for locally generating a ratio clock on a chip includes generating a global clock signal having a global clock cycle. A centralized state machine includes a counter going through a complete cycle in response to a non-integer number of global clock cycles, the state machine generating a control signal in response to the counter. The control signal is provided to staging latches, the staging latches generating a clock high signal and a clock low signal. Local pass gates generate an (n+0.5)-to-1 clock signal in response to the global clock signal, the clock high signal and the clock low signal.

Abstract: A circuit for measuring timing uncertainty in a clocked digital path and in particular, the number of logic stages completed in any clock cycle. A local clock buffer receives a global clock and provides a complementary pair of local clocks. A first local (launch) clock is an input to a delay line, e.g., 3 clock cycles worth of series connected inverters. Delay line taps (inverter outputs) are inputs to a register that is clocked by the complementary clock pair to capture progression of the launch clock through the delay line and identify any variation (e.g., from jitter, VDD noise) in that progression. Global clock skew and across chip gate length variation can be measured by cross coupling launch clocks from a pair of such clock buffers and selectively passing the local and remote launch clocks to the respective delay lines.

Abstract: Detecting and correcting errors in arrays after ABIST testing, after ABIST testing, detected errors are faults are isolated by blowing a fuse.

Abstract: A method for locally generating a ratio clock on a chip includes generating a global clock signal having a global clock cycle. A centralized state machine includes a counter going through a complete cycle in response to a non-integer number of global clock cycles, the state machine generating a control signal in response to the counter. The control signal is provided to staging latches, the staging latches generating a clock high signal and a clock low signal. Local pass gates generate an (n+0.5)-to-1 clock signal in response to the global clock signal, the clock high signal and the clock low signal.

Abstract: A computing system is provided which includes a processor having a cache memory. The cache memory includes a plurality of independently configurable subdivisions, each subdivision including a memory array. A service element (SE) of the computing system is operable to cause a built-in-self-test (BIST) to be executed to test the cache memory, the BIST being operable to determine whether any of the subdivisions is defective. When it is determined that one of the subdivisions of the cache memory determined defective by the BIST is non-repairable, the SE logically deletes the defective subdivision from the system configuration, and the SE is operable to permit the processor to operate without the logically deleted subdivision. The SE is further operable to determine that the processor is defective when a number of the defective subdivisions exceeds a threshold.

Abstract: A system, method, and computer program product for scan testing a device under test (DUT). In one embodiment, compressed test data comprising packets are received at a serial test data input. The packets contain encoded data characterizing a test data bit stream and each includes a bucket select field and a fill value field. The bucket select field contains an bucket select value that maps to a length of a bit-string. The fill value field contains a fill value indicating the uniform binary value of the bit-string. The compressed test data is then expanded and the expanded test data is scanned into internal structures of the DUT to test internal structures of the DUT. In a preferred embodiment, the compressed test data is received at a first clock rate. The test data is expanded and scanned into the internal structures of the DUT at a second clock rate that is higher than the first clock rate.

Abstract: A method for locally generating a ratio clock on a chip includes generating a global clock signal having a global clock cycle. A centralized state machine is provided that includes a counter going through a complete cycle in response to a non-integer number of global clock cycles, the centralized state machine generating a control signal in response to the counter. The control signal is provided to staging latches, the staging latches generating a clock high signal and a clock low signal, the clock high and clock low signal having patterns derived from a waveform of a target divided ratio clock and the clock high and clock low signals have patterns that match the targeted divided clock frequency and duty cycle. Local pass gate are provided for generating an (n+0.5)-to-1 clock signal in response to the global clock signal, the clock high signal and the clock low signal.

Abstract: Circuitry for locally generating a ratio clock on a chip. The circuitry includes circuitry for generating a global clock signal having a global clock cycle. A state machine includes a counter going through a complete cycle in response to a non-integer number of global clock cycles. The state machine generates a control signal in response to the counter. Staging latches receive the control signal and generate a clock high signal and a clock low signal, the clock high signal and the clock low signal having patterns derived from a waveform of a target divided ratio clock, the clock high signal and the clock low signals have patterns that match the targeted divided clock frequency and duty cycle. A local pass gate receives the clock low signal and the clock high signal and generates an (n+0.5)-to-1 clock signal in response to the global clock signal, the clock high signal and the clock low signal.

Abstract: Systems, methods and apparatus are provided for isolating a defect in a scan chain. The invention includes modifying a first test mode of a plurality of latches included in a scan chain, operating the latches in the modified first test mode, and operating the plurality of latches included in the scan chain in a second test mode. A portion of the scan chain adjacent and following a stuck-@-0 or stuck-@-1 fault in the scan chain may store and/or output a value complementary to the value on the output of the previous portion of the scan chain due to the fault. Such values may be unloaded from the scan chain and used for diagnosing (e.g., isolating a defect in) the defective scan chain. Numerous other aspects are provided.

Abstract: The output register of an array and the Multiple Input Signature Register (MISR) logic is implemented with one set of L1/L2 master/slave latches and single additional slave latch. This new combined logic uses less critical area on a chip without a performance impact on the array access time or circuit testing.

Abstract: An SRAM cell that is accessed by a single word line and separate access transistors for read and write operations. A pair of write bit line transfer devices provide respectively access to the right and left sides of cross coupled pull-up, pull-down transistor pairs for a write operation, and a single read bit line transistor in series with the word line transistor, when selected, reads the content of the cell.

Abstract: An output of an element under test is captured and stored, through a multiplexer, in a capture register. At a clock edge (either rising or falling edge) the element under test catches the “edge” and “strobes” the output. The multiplexer is strobed, and the delay and duty cycle are measured. Both the rising and falling edge are used as the timer.

Abstract: A soft-fust test algorithm is distributed on-chip from an ABSIT engine through an LSSD shift register chain to dynamically evaluate a plurality of arrays with redundancy compensation for bad elements and repair those that are fixable. Using single-bit MISR error evaluation an ABSIT test sequence is executed concurrently on all arrays through the shift register chain. If any arrays are in error, redundancy compensation is employed and the ABIST test is repeated for all possible array redundant combinations until a functional configuration for each array is identified or all possible redundant combinations have been tried. Once functioning array configurations are verified, the associated soft-fuse states can be used to blow fuses and/or extracted for further system setup, permanent fuse-blowing and yield analysis. Multiple shift register chains driven by separate ABIST engines may be required to test all arrays on a chip.

Abstract: A method and apparatus for providing flexible modular redundancy allocation for memory built in self test of random access memory with redundancy. The apparatus includes a first redundancy support register that includes inputs for receiving an address of a location in memory under test and data relating to must fix repair elements. The address includes a row and column vector of the location. The first redundancy support register also includes outputs for transmitting the address and data. The apparatus also includes a second redundancy support register including inputs for receiving the address and data from the outputs of the first redundancy support register. Each of the inputs of the second redundancy support register shares a one-to-one correspondence to each of the outputs of the first redundancy support register. The apparatus further includes allocation logic for providing a modular implementation of the first redundancy support register and the second redundancy support register.

Abstract: This invention describes a method of synchronizing test clocks in an LSSD system to achieve near simultaneous arrival of the clock signals at the inputs of all LSSD registers. The method relies on pipelining the latches to distribute the test clocks, where all pipeline latches are synchronized by the system clock. This enhancement improves the frequency at which the test clocks switch and improve the testing throughput by reducing testing time, resulting in significant reductions in testing hardware and overall time required for system test, without compromising any of the benefits associated with conventional LSSD techniques. The method further enhances the distribution of the test clock signals to points throughout the entire chip, with a distribution network that is tailored according to a desired LBIST speed.