Texas Instruments Corporation

Jais Abraham

Ajit Deepak Gupte

Sandeep Jain

Nikila Krishnamoorthy

G Subash Chandar

Naga Satya Srikanth Puvvada

Amit Brahme

Rohit Goel

Shankaranarayana Karantha Deshamangala

According to an aspect of present invention, modules designed to operate with different frequency in functional (normal) mode are tested using a sequential scan based technique at the respective frequencies. In one embodiment the interface logic connecting the two modules is tested for at-speed performance (i.e., the same speed at which the interface would be operated in functional mode during normal operation).

Sequential scan based techniques to test interface between modules designed to operate at different frequencies

Scan tests tolerant to indeterminate states generated in an integrated circuit (IC) when employing signature analysis to analyze test outputs. Bits with indeterminate-state are masked when scanning out the bits from the scan chains to force such indeterminate bits to a known logic level. This prevents a signature generator receiving the outputs of a scan test from generating an invalid signature. In an embodiment, masking information is stored in encoded form in a memory. A decoding circuit decodes the masking information and provides mask data under control from a mask controller. Mask data is sent to a masking circuit which also receives corresponding bits from scan-out vectors, with each scan-out vector being generated by a corresponding one of multiple scan chains. The output of the masking circuit may be provided in a compressed form to the signature generator circuit.

Scan tests tolerant to indeterminate states when employing signature analysis to analyze test outputs

Testing the components of I/O paths in an integrated circuit at-speed operation (i.e., the speed at which the integrated circuit would be operated during normal non-test mode). In an embodiment, boundary scan cells of different paths are connected in a scan chain, and each scan cell tests the corresponding component (e.g., buffer) by launching data at a first time instance and receiving the result of the data at a second time instance, with the duration between the first time instance and the second time instance corresponding to the at-speed operation. If the data is received accurately, the component may be deemed to be operating accurately at-speed.

Testing components of I/O paths of an integrated circuit

A non-robust test pattern, which causes a transition on a path of interest as well as off-paths, may be selected as being suitable for performing delay analysis of the path of interest (e.g., critical path) if the transitions caused on the off-paths would not overlap with the transition caused on the path of interest. In other words, an aspect of the present invention enables at least some non-robust test patterns to be used for performing delay analysis. As non-robust test patterns (as well as robust test patterns) can be used to perform delay analysis, the number of possible test patterns for performing speed analysis can be increased.

Increasing possible test patterns which can be used with sequential scanning techniques to perform speed analysis

A launch multiplexor which enables a desired bit to be stored into a desired memory element when using sequential scanning techniques (e.g., automatic test pattern generation (ATPG)). The launch multiplexor may be employed in addition to a scan multiplexor, which enables the test pattern bits or normal operating input to be selected and stored in the desired memory element. The scan multiplexor is used to scan-in a test pattern and evaluate a first input, and the launch multiplexor provides the control to store a desired bit into the corresponding memory element. Another output may be evaluated after storing the desired bit. In an embodiment, launch multiplexors are used associated with only memory elements in the critical paths, and the delay in transitioning from one output to another may be conveniently measured.

Controlling the content of specific desired memory elements when testing integrated circuits using sequential scanning techniques

A scannable storage circuit is provided that has a separate a scan output buffer for driving the scan output. The scan output buffer is coupled to the storage element in a parallel manner with the data output buffer so that normal data propagation is not delayed. The scan output buffer is gated by a scan enable input so that the scan output is quiescent when the storage circuit is not in scan mode. The selectively enabled scan output buffer is embodied with only four transistors.

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Malapuram, India

Jais Abraham