An evaluation LSI includes a noise generation circuit generating a controlled amount of noise controlled from outside of the LSI, and a delay measurement circuit measuring a signal delay of a delay circuit influenced by the noise. The relationship between the amount of noise and the signal delay is determined. A device-under-test (DUT) LSI includes a functional circuit and a delay circuit having a signal delay influenced by the operation of the functional test. By evaluating the signal delay of the delay circuit in the DUT LSI, the amount of noise therein is estimated based on the determined relationship.

A technique for detecting changes in a signal that is measured and reported by quantization uses a model that is updated in response to the sampling of quantized values representing the signal. In one stage, (i) frequencies of occurrences of different sampled quantized values in the stage are calculated and (ii) mean frequencies for each of the different sampled quantized values in the stage are calculated and recorded. In a next stage, frequencies of occurrences of different sampled quantized values occurring after an end of the preceding stage are calculated and statistically compared with the mean frequencies of the different sampled quantized values determined in the preceding stage. Dependent on this comparison, a notification may be issued indicating the signal is anomalously changing.