International Business Machines Corporation

Raghu Gaurav GopalaKrishnaSetty

Mary Prilotski Kusko

Steven Michael Douskey

Cedric Lichtenau

Satya R S Bhamidipati

Hari Krishnan Rajeev

James Douglas Warnock

Balaji Upputuri

Kanad Basu

Sumit Panigrahi

Thamaraiselvan Subramani

Operating pulsed latches on a variable power supply including turning on a first power rail powering a first latch of an integrated circuit, wherein the first latch is a pulsed latch; turning on a second power rail powering a second latch of the integrated circuit, wherein the second latch is operatively coupled to the first latch; performing a scan operation using the first latch and the second latch; turning off the first power rail powering the first latch; and performing a functional operation using the second latch, wherein the first power rail powering the first latch is off during the functional operation.

Operating pulsed latches on a variable power supply

Method and apparatus to test an integrated circuit includes retrieving power distribution data relating to an integrated circuit and designating a segment that includes at least one component of the integrated circuit. A switching limit associated with the segment may be set based on the power distribution data. Processes further generate a testing pattern that includes the determined switching limit associated with the segment.

Dynamically power noise adaptive automatic test pattern generation

Aspects include a method for logic built-in self-testing (LBIST) for use in an integrated circuit with scan chains. The method includes programming a product control generator and a pattern generator with an LBIST pattern comprising at least a number of loops. The LBIST pattern is executed by generating scan-in test values for scan chains with the pattern generator and controlling at least one test parameter with the product control generator. Scan-out responses are collected from the scan chains in a signature register, and a start request is received from a chip tester. The LBIST is started in response to the start request. Test summary data is reported to the chip tester before the whole number of loops has been executed.

Logic built in self test circuitry for use in an integrated circuit with scan chains

Aspects include a system having logic built-in self-test (LBIST) circuitry for use in an integrated circuit with scan chains. The system includes a pattern generator configured for generating scan-in test values for said scan chains; a signature register configured for collecting scan-out responses from said scan chains after a clock sequence; an on-product control generator configured for controlling at least one test parameter; one or more microcode array or memory elements configured to receive inputs to initialize fields in the microcode array or memory elements; and a test controller. The test controller includes a reader component configured for reading test parameters from a field of the microcode array or the memory elements; and a programming component configured for configuring the on-product control generator and the pattern generator with a LBIST pattern according to the read test parameters.

Embodiments herein describe the design of a scan cell within an integrated circuit. The scan cell comprises a memory element, e.g., a flip-flop, and a plurality of output buffer stages. The scan cell also comprises selection logic, e.g., a plurality of transistors. The selection logic selectively activates and deactivates one or more of the plurality of output buffer stages in response to a scan enable signal to change an output latency of the scan cell. The scan cell operates in either a test mode or a normal functional mode according to the scan enable signal. The output latency of the scan cell is changed to mitigate or prevent hold violations.

Adjusting latency in a scan cell

Embodiments herein describe the design of a scan cell within an integrated circuit. The scan cell operates in either a test mode or a normal functional mode according to a scan enable signal. The scan cell comprises delay logic including a plurality of delay elements, e.g., a plurality of transistors. The delay logic activates the delay elements only when the scan cell operates in the test mode. The delay elements are activated to change a scan latency of the scan cell. The scan latency of the scan cell is increased to mitigate or prevent hold violations.

Crosstalk effects can be taken into account in automatic test pattern generation (ATPG) by providing crosstalk fault models, determining paths and/or nodes to be sensitized to activate each crosstalk fault, and optimizing to enable as many crosstalk faults as possible with a given pattern, subject to constraints. Constraints can include threshold numbers of endpoints/observation points and/or attempts to sensitize. Intermediate nodes in a crosstalk fault model path to an observation point can also be determined and/or sensitized.

Automatic test pattern generation (ATPG) considering crosstalk effects

Aspects of the invention provide for a method of delay defect testing in integrated circuits. In one embodiment, the method includes: generating at least one test pattern based on a transition fault model type; evaluating a dynamic voltage drop for the at least one pattern during a capture cycle and generating a voltage drop value for the at least one test pattern; performing a static timing analysis, using the voltage drop value for the at least one test pattern; evaluating a plurality of paths in the at least one pattern; and masking each path that fails to meet a timing requirement.

Growing community of inventors

Bengaluru, India

Raghu Gaurav GopalaKrishnaSetty