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In recent high-density and low-power VLSIs, soft errors occurring on not only memory systems and the latches of logic circuits but also the combinational parts of logic circuits seriously affect the operation of systems. The conventional soft error tolerant methods for soft errors on the combinational parts do not provide enough high soft error tolerant capability with small performance penalty. This paper proposes a class of soft error masking circuits by using a Schmitt trigger circuit and pass transistors. The paper also presents construction of soft error masking latches (SEM-Latches) capable of masking transient pulses occurring on combinational circuits. Moreover, experimental results show that the proposed method has higher soft error tolerant capability than the existing methods. For driving voltage VDD=3.3V, the proposed method is capable of masking transient pulses of magnitude 4.0V or less.

This paper presents a low area on-chip delay measurement system using an embedded delay measurement circuit. To reduce the area, the proposed method does not demand the measurement of the exact path under measurement, but the measurement of a path including the path under measurement and wires of clock tree unlike the conventional methods. The proposed Stop Signal Generator (SSG) consists of OR gate trees and a selector circuit. In addition, the area of SSG is lower than the conventional one. SSG is additional circuit which sends the transition from the output of the path under measurement to the embedded delay measurement circuit. Therefore, the area of the proposed system is lower. Because the area is low, the proposed method can be used for small-delay defect detection in manufacturing testing and failure prediction due to aging after shipment. We can apply the proposed delay measurement system to any embedded delay measurement circuit that measures the time difference between the two input signal transitions sent to the circuit. The evaluation shows that the area overhead is 16.54%. It is 6.62% smaller than the conventional method, and 8.41% larger than standard scan design.

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