An On-Chip Digital Environment Monitor for Field Test

An on-chip environment monitor that can estimate a chip temperature and a power supply voltage has been developed to assist accurate circuit delay measurement by field test. The monitor consists of digital circuits and satisfies several features desired for the field test. This paper describes the architecture of the monitor and how to estimate the temperature and voltage in field, and finally shows simulation and TEG results on estimation accuracy.

I. Introduction(Heading 1)

In order to ensure the reliability of VLSI systems, field test for VLSIs after shipping is known as an effective way. The main objective of the field test is to detect or predict aging-induced faults of the VLSIs. Because the typical phenomenon of the aging-induced faults such as BTI and HCI is to increase a circuit delay [1]–[4], delay testing to measure a delay margin of the circuit is effective in field test. On the other hand, the measured delay is varied depending on the environment in the measurement because the temperature and voltage are not controlled or fixed in field. Thus it is important to revise the measured delay such that the effect of variation in the temperature and voltage is removed from the measured delay.