Lsi Logic Corporation

Robert M Walker, Iii

Dick L Liu

Anthony Yap Wong

A method of testing integrated circuits at high operating speeds is provided which is applicable to sequential logic circuits such as ASICs. A general purpose ASIC tester applies test vectors to the integrated circuit under test. The logic input signals are held unchanged and a series of high speed clock signals (a clock burst) are applied to the clock terminals of the integrated circuit. These clock signals are provided at the speed at which it is desired to test the integrated circuit. Then the output terminals are observed to determined if the device is in the expected state (as determined by simulation) after the clock burst. The process is repeated until no further output terminals change state, and then the device may be reinitialized and another series of state changes initiated. Thus every path in the circuit may be tested at high speed by a conventional low speed tester.

Testing of integrated circuits using clock bursts

A high-speed CMOS output buffer reduces transient current surges and provides high output DC drive. The buffer includes a first and a second CMOS inverter connected in parallel. Each of the two CMOS inverters includes an N channel and a P channel transistor. The gates of the transistors in the first inverter are controlled by a first control inverter having a first selected switching threshold voltage. The gate of the P channel transistor in the second inverter is controlled by a second control inverter having a switching threshold voltage higher than that of the first control inverter. The gate of the N channel transistor in the second inverter is controlled by a third control inverter having a switching threshold voltage lower than that of the first control inverter.

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Atherton, CA, United States of America

Robert M Walker, Iii