Experimental Characterization of Multitone EM Immunity of Integrated Oscillators Under Thermal Stress

The reliable operation of an integrated circuit can be affected by environmental changes, such as of multiple frequency electromagnetic (EM) disturbances and temperature variations. This paper compares the performance of two oscillator circuits, namely a current-starved voltage controlled oscillator and a ring oscillator integrated into a chip, in terms of their immunity to multitone direct power injection while under the influence of thermal stress. The objective is to demonstrate by the means of measurements the synergistic effect caused by multitone EM disturbances in a test chip, in contrast to the conventional single-tone EM disturbances. Moreover, the multitone immunity levels of integrated blocks with different architectures but similar functionality are analyzed at extreme temperature deviations. Bayesian networks (BN) are applied in order to visualize the probability of circuit failure due to multitone disturbances and temperature influence. Additionally, noisy-OR and improved-adaptive-recursive-noisy-OR (I-ARNOR) probabilistic models are implemented to identify the types of causal interactions (i.e. inhibition and positive causality) between multitone disturbances and to predict the probability of failure due to higher order multitone disturbances, respectively.