Mediatek Singapore Pte. Ltd.

Kin Hooi Dia

Joseph Patrick Geisler

Dimitry Patent

A scan test circuit includes: a pulse generator, for generating differential pulses according to a system clock signal; a functional path, including: a D-type latch clocked by the differential pulses; a test path, including: a scan latch clocked by a test clock signal; and a tri-state inverter. When a test enable signal is enabled, the generation of the differential pulses is disabled.

Scan test circuit with pulse generator for generating differential pulses to clock functional path

A pulse latch includes a pulse generator and a latch circuit. The pulse generator generates first and second pulse signals. The first pulse signal is generated when a test enable signal is in a first state, and the second pulse signal is generated when the test enable signal is in a second state. The latch circuit outputs the latched signal by selectively latching a normal data input signal or a test data input signal. The latch circuit includes first and second tri-state elements. The first tri-state element is controlled by the first pulse signal to enable the test data input signal to be latched when the test enable signal is in the first state. The second tri-state element is controlled by the second pulse signal to enable the normal data input signal to be latched when the test enable signal is in the second state.

Pulse latches

A scan test circuit includes: a functional path, including: a D-type latch, for receiving an input and generating an output, the D-type latch including a feedback node; and a test path, including: a scan latch, for receiving a test input and generating an output. The scan test circuit also includes a tri-state inverter. The output of the test path is input to the feedback node of the D-type latch and also input to the tri-state inverter. The functional path is clocked by pulses generated by a pulse generator according to a system clock. The test path is clocked by a test clock generated according to a test enable signal and the system clock. When the test enable signal is enabled, the generation of the pulses is disabled.

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Hsinchu, Taiwan

Kin Hooi Dia