Intel Corporation

Hehching Harry Li

Michael Spica

Md Rezwanur Rahman

Ajay Ojha

Methods and apparatus to test memories, such as, for example, caches of processors, are disclosed. In one aspect, an apparatus may include a pseudo random address generation unit, such as, for example, including a linear feedback shift register, to generate pseudo random memory addresses, and a deterministic data generation unit, such as, for example, including a state machine, to generate deterministic data to be written to the pseudo random memory addresses. Computer systems and other electronic systems including such apparatus are also disclosed.

Testing memories

A novel apparatus and methods provide the capability to structural test device input/output pins which are not connected to an external tester during the testing process. The method does not require a new Design For Test logic block, but rather, the method modifies existing registers on the chip to function as a (Pseudo Random Pattern Generator) PRPG and a MISR (Multiple Input Signature Register). The PRPG generates input patterns. The MISR generates an output signature. PRPG and MISR are both based on LFSR (Linear Feedback Shift Register). This allows running a random pattern generated by the PRPG, testing at-speed a path from the PRPG through the I/O logic circuitry interfacing to core logic, and storing a signature pattern in the MISR. The testing will take place at native speed of the device and no connection to the pins is required externally.

Method of determining non-accessible device I/O pin speed using on chip LFSR and MISR as data source and results analyzer respectively

A method and an apparatus utilizing mux scan flip-flops to test for timing-related defects. In one embodiment, a delay circuit is used to act as a buffer for a scan enable signal received by the mux scan flip-flops of a test circuit. The scan mode signal is first sent to the delay circuit, which then distributes the scan mode signal to the mux scan flip-flops. Since each delay circuit can serve as the buffer for numerous mux scan flip-flops, the scan mode signal may be sent initially to a smaller number of delay circuits instead of the thousands of mux scan flip-flops that may be distributed throughout the entire integrated circuit. Furthermore, in one embodiment the delay circuit delays propagation of active-to-inactive transitions of the scan enable signal by one clock cycle, synchronizing the system clock cycle with the active-to-inactive transitions of the scan mode signal. In one embodiment, inactive-to-active transitions of the scan enable signal are propagated without the one clock cycle delay. With the present invention, the mux scan flip-flops may be loaded and unloaded with test data at slower scan clock speeds, and the integrated circuit may be operated at full system clock speeds for as few as two cycles to detect speed-related defects in accordance with the teachings of the present invention.

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Portland, OR, United States of America

Hehching Harry Li