Abstract: A critical-path timing sensor detects set-up timing failures from a functional critical path to a path flip-flop. The functional critical path carries test data during test mode, and normal data during normal device operation. The path flip-flop's D input and Q output are compared by an exclusive-OR (XOR) gate and sampled by an early capture flip-flop that is clocked by a delayed clock, sampling D and Q just after the path flip-flop is clocked. When set-up time fails, D and Q differ just after the clock edge and a timing failure is latched. Timing failures activate a controller to increase VDD, while VDD is reduced in the absence of timing failures. Process variations are accounted for, allowing for lower power or faster operation. A margin delay between the functional critical path end and the early capture flip-flop detects timing failures before they occur in the path flip-flop.

Abstract: Toggling functional critical path timing sensors measure delays in toggling functional critical paths that are replicas of actual critical paths or representations of worst-case delay paths. A Toggle flip-flop or Linear-Feedback-Shift Register (LFSR) drives high-transition-density test patterns to the toggling functional critical paths. When a toggling functional critical path's delay fails to meet set-up timing requirement to a next register, the toggling functional critical path timing sensors signal a controller to increase VDD. When no failures occur over a period of time, the controller decreases VDD. A margin delay buffer adds a delay to the toggling functional critical path before being clocked into an early capture flip-flop. A reference register receives the test pattern without the delay of the toggling functional critical path, and an exclusive-OR (XOR) gate compares outputs of reference and early capture flip-flops to generate timing failure signals to the controller.

Abstract: Toggling functional critical path timing sensors measure delays in toggling functional critical paths that continuously receive patterns from an aging pattern generator. Wear is accelerated. A margin delay adjustment controller sweeps margin delays until failures occur to measure delays. The margin delay is then adjusted in functional critical path timing sensors that add the margin delay to functional critical paths that carry user data or chip controls during normal operation. When the path delays fail to meet requirements, the functional critical path timing sensors signal a controller to increase VDD. When no failures occur over a period of time, the controller decreases VDD. Wear on the toggling functional critical paths is accelerated using both toggle and low-transition-density patterns. Circuit aging is compensated for by increasing margin delays to timing sensors.

Abstract: CAD software examines delays of paths in a design from design engineers and first selects the longest paths. Then all paths that converge with these longest paths are examined for delays, and a fastest converging path is selected for each of the longest paths. The longest paths are again sorted by the fastest converging delay, and paths with slower converging paths are selected to be Functional Critical Paths (FCP's). Functional critical path timing sensors are added to each FCP to test setup time with an added margin delay. When the margined path delays fail to meet setup requirements, the functional critical path timing sensors signal a controller to increase VDD. When no failures occur over a period of time, the controller decreases VDD. The CAD software can replicate some of the FCP's and add toggle pattern generators and timing sensors and a margin controller to adjust the margin delay.

Abstract: Described herein are apparatuses and methods for enhancing timing delay fault coverage during testing of functional circuitry. In one embodiment, an apparatus includes functional circuitry for performing functional operations and test logic coupled to the functional circuitry to enhance timing delay fault coverage for the functional circuitry with at-speed test sequences. The test logic includes a plurality of partitions of scan flip-flops and an independent partition scan enable input signal for each partition for enabling or disabling each partition.

Abstract: User data or constantly toggling functional critical path timing sensors measure delays in actual critical paths that include a RAM. Variable resistors or variable capacitors are added to RAM bit lines for redundant cells to delay bit-line sensing by sense amplifiers. The sense amplifiers' delayed data is compared to non-delayed data from normal selected RAM cells to detect timing failures. Variable resistors or capacitors may also be added between the write drivers and bit lines to delay writing data into the redundant cells. A margin delay adjustment controller sweeps margin delays for constantly toggling paths until failures. A margin delay is then adjusted and added to functional critical paths that carry user data. Functional critical path timing sensors test setup time with the added margin delay. Timing failures cause VDD to increase, while a controller reduces VDD when no failures occur. Actual delays through the RAM adjust VDD.

Abstract: Described herein are apparatuses and methods for enhancing timing delay fault coverage during testing of functional circuitry. The present design includes a novel at-speed (e.g., at clock speed of functional circuitry during functional mode) mechanism to improve transition delay fault testing. In one embodiment, an apparatus includes functional circuitry for performing functional operations and test logic coupled to the functional circuitry. The test logic enhances timing delay fault coverage for the functional circuitry. The test logic includes scan flip-flops arranged in at least one scan chain and at least one input signal that is generated based on at least one scan override signal for overriding at least one scan enable signal.

Abstract: A system and method integrate mask layout tools to automate the generation of mask layouts for fabricating an integrated circuit corresponding to an input netlist and a timing specification. The mask layout is generated by the method including the steps of automatically sizing transistors specified in the netlist, clustering the sized transistors into cells, generating a cell library, and placing-and-routing the cells to generate the mask layout. The system includes associated memory and stored programs, including a plurality of mask layout tools; and a processor operated by an automatic mask layout generation program for sequentially applying the plurality of mask layout tools to generate the mask layout from the input data.