Abstract
Precise measurement of digital circuit degradation is a key aspect of aging tolerant digital circuit design. In this study, we present a fully digital on-chip reliability monitor for high-resolution frequency degradation measurements of digital circuits. The proposed technique measures the beat frequency of two ring oscillators, one stressed and the other unstressed, to achieve 50 × higher delay sensing resolution than that of prior techniques. The differential frequency measurement technique also eliminates the effect of common-mode environmental variation such as temperature drifts between each sampling points. A 265 × 132 μ2test chip implementing this design has been fabricated in a 1.2 V, 130 nm CMOS technology. The measured resolution of the proposed monitoring circuit was 0.02%, as the ring oscillator in this design has a period of 4 ns; this translates to a temporal resolution of 0.8 ps. The 2 μs measurement time was sufficiently short to suppress the unwanted recovery effect from concealing the actual circuit degradation.
Original language | English (US) |
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Pages (from-to) | 874-880 |
Number of pages | 7 |
Journal | IEEE Journal of Solid-State Circuits |
Volume | 43 |
Issue number | 4 |
DOIs | |
State | Published - Jan 2008 |
Keywords
- Aging
- Degradation
- Monitoring circuit
- NBTI
- Reliability