1. 1 Silicon Odometer: An On-Chip Reliability Monitor for Measuring Frequency Degradation of Digital Circuits NBTI impact mitigation techniques Guard-banding Size up devices Toggle circuit nodes Lower temperature V tp and V dd tuning NBTI impact on digital circuits F max Leakage current SRAM cell stability SRAM read/write margin Bottom line: Need to accurately measure the NBTI effect and develop compact models

2. 2 Silicon Odometer Phase Comp. Stressed ROSC (freq=f stress )... Reference ROSC A B C PC_OUT Measurement Stress period V DD_NOM V DD_STR 0V (freq=f ref ) (freq=f ref - f stress ) Two free running ROSCs for beat frequency detection Count PC_OUT to determine frequency degradation Insensitive to environmental variations High delay sensing resolution Fully implemented by digital circuits

3. Labview GUI 3 Summary Measurement work bench 0.00% 0.05% 0.10% 0.15% 0.20% 0.25% 0.30% 0200040006000 Time (sec) Frequency degradation V stress =V0, 30  C Fully digital, minimal calibration Sub-picosecond sensing resolution (<0.02% or <0.8ps) Microsecond measurement time for minimal recovery (2us) Applicable as a on-chip reliability monitor