Abstract: System-accessible frequency measuring circuits and procedures permit on-chip testing of the oscillators and provide test results observable off chip via LSSD scan paths. This allows a rapid ensemble of ring oscillators in a standard ASIC test flow without the need for on chip analog test equipment (the test apparatus has effectively been created on device and can be digitally configured, operated and read). Frequency measuring logic that can 1) functionally operate to measure the frequency of the ring oscillators; 2) participate in traditional logical tests such as LSSD and LBIST to verify that the circuit is manufactured correctly and is likely to operate and 3) operate in a special ring-oscillator test mode, that allows the logic to operate on a tester very similarly to the way it does functionally. In this mode, the frequency measuring logic can be scanned to a specific state, started by pulsing a digital I/O, and the measured analog value can be scanned out sometime later after the test has completed.

Abstract: System-accessible frequency measuring circuits and procedures permit on-chip testing of the oscillators and provide test results observable off chip via LSSD scan paths. This allows a rapid ensemble of ring oscillators in a standard ASIC test flow without the need for on chip analog test equipment (the test apparatus has effectively been created on device and can be digitally configured, operated and read). Frequency measuring logic that can 1) functionally operate to measure the frequency of the ring oscillators; 2) participate in traditional logical tests such as LSSD and LBIST to verify that the circuit is manufactured correctly and is likely to operate and 3) operate in a special ring-oscillator test mode, that allows the logic to operate on a tester very similarly to the way it does functionally. In this mode, the frequency measuring logic can be scanned to a specific state, started by pulsing a digital I/O, and the measured analog value can be scanned out sometime later after the test has completed.

Abstract: A method for real time capture of the desired failing chip cell diagnostic information from high speed testing of a semiconductor chip with on chip LSSD registers having built in self test functions and a fail trap register, and there is provided a programmable skip fail counter, and a hold and compare function circuit. The programmable skip counter is enabled for initialization to a “record first fail” mode, and then with non-zero values of the skip counter to a “record next fail” mode with scan initialization of the LSSD registers of the semiconductor chip. The diagnostic information for the chip is obtained by collecting data from scanning the circuits of said semiconductor chip for a failing cell for immediate scan-out off-chip at a level of assembly test.

Abstract: An exemplary embodiment of the invention is a method for LBIST testing integrated circuit. The method includes generating a plurality of multi-bit test patterns and grouping the multi-bit test patterns by a plurality of test pattern partitions including a first test pattern partition having a first number of bits and a second test pattern partition having second number of bits greater than the first number. The first test pattern partition is applied to the integrated circuit to generate a first signature that is compared to a first reference signature to detect a failure. The second test pattern partition is applied to the integrated circuit to generate a second signature that is compared to a second reference signature to detect a failure in the integrated circuit.

Abstract: A method and apparatus for real time capture of the desired failing chip cell diagnostic information from high speed testing of a semiconductor chip having built in self test functions and a fail trap register, and there is provided a programmable skip fail counter, and a hold and compare function circuit. The programmable skip counter is enabled for initialization to a “record first fail” mode, and then with non-zero values of the skip counter to a “record Nth+l fail” mode. The “Record first fail” is considered the default or base function when the initial state of all registers is defined to be “0”, and is obtained through scan initialization of the LSSD registers of the semiconductor chip.