Stmicroelectronics International N.v.

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Venkata Narayanan Srinivasan

Balwinder Singh Soni

A test circuit is operable in ATPG mode and LBIST mode. The test circuit includes a clock selection circuit. The clock selection circuit includes clock logic circuitry to receive an LBIST mode signal and an ATPG mode signal and to generate an indication of whether the test circuit is operating in either the ATPG mode or the LBIST mode, a multiplexing circuit to receive an ATPG clock and a functional clock as input and output a selected one of the ATPG clock and the functional clock, and a clock gate circuit enabled in response to enable signals. The enable signals are an inverse of a selected one of the ATPG clock and the functional clock. The clock gate circuit receives the indication of whether the test circuit is operating in either the ATPG mode or the LBIST mode and generates a test clock as a function of the indication.

Clock selection circuit and test clock generation circuit for LBIST and ATPG test circuit

A test circuit receives LBIST and ATPG mode signals, and generates a first output as high when in ATPG or LBIST, and a second output as low when in ATPG or LBIST. A multiplexing circuit receives an ATPG clock and functional clock, and outputs one. A clock gate circuit includes a first latch receiving the second output, and an enable input receiving an inverse of the ATPG clock or functional clock. A second latch receives the first output, and has an enable input receiving the inverse of the ATPG clock or functional clock. The clock gate circuit includes a first AND gate receiving output of the first latch and ATPG clock or functional clock, a second AND gate receiving output of the second latch and the ATPG clock or LBIST clock, and an OR gate receiving outputs of the first and second AND gates, and generating a test clock.

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Greater Noida, India

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