Hitachi, Ltd.

Yasuyoshi Sunaga

Kozaburo Kurita

Yuko Ito

Hideki Sakakibara

Tomoji Nakamura

Koki Tsutsumida

Atsushi Hazeyama

There is provided a semiconductor integrated circuit in which a ring oscillator is formed by a variable delay circuit to cause the ring oscillator to oscillate (S) at the test operation of the variable delay circuit and it is determined whether the variable delay circuit is normal or abnormal depending on whether the ring oscillator satisfies a predetermined monotonic increase condition (S) and a predetermined linearity condition (S).

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Tokyo, Japan

Yasuyoshi Sunaga