NBTI degradation and recovery in analog circuits: Accurate and efficient circuit-level modeling

We investigate the NBTI degradation and recovery of pMOSFETs under continuously varying analog-circuit stress voltages, and thereby generalize existing digital-stress NBTI studies. Starting from our ultra-fast NBTI measurements and an extensive TCAD analysis, we study two physics-based compact models for analog-stress NBTI including recovery. The high accuracy of both models is evidenced from single-FET analog stress and circuit-level ring oscillator experiments. Their numerical efficiency allows a direct coupling to circuit simulators and permits to accurately account for NBTI already during circuit design. Furthermore, one of the models calculates the time-dependent NBTI variability of single-FET and of circuit performance parameters. We demonstrate our NBTI models on a ring oscillator and calculate the mean drift and statistical distribution of its oscillation frequency.