Patent ID: 7495519

Claim:
A system for monitoring reliability of a digital system, the system comprising: at least one ring oscillator sensor implemented in association with the digital system for facilitating monitoring reliability thereof, the digital system including a circuit composition comprising at least one logic type, the at least one logic type comprising at least one device type, and wherein the at least one ring oscillator sensor includes a circuit composition comprising one or more of the at least one logic type or the at least one device type of the digital system selected based on the circuit composition of the digital system to correlate aging of the at least one ring oscillator sensor to aging of the digital system, the at least one ring oscillator sensor outputting count signals; counter logic coupled to the at least one ring oscillator sensor for converting the count signals to an oscillation frequency of the at least one ring oscillator sensor; and control logic coupled to the counter logic for periodically evaluating oscillation frequency of the at least one ring oscillator sensor and generating a warning signal indicative of reliability degradation thereof, and hence of the digital system, if at least one of: (i) a measured or estimated oscillation frequency of the at least one ring oscillator sensor is below a warning threshold frequency for the digital system; or (ii) a measured or estimated rate of change in a difference between measured oscillation frequencies of the at least one ring oscillator sensor exceeds an acceptable rate of change threshold for the digital system.