Analysis of hot carrier and NBTI induced device degradation on CMOS ring oscillator

The degradation of CMOS ring oscillator caused by hot carrier and negative bias temperature instability (NBTI) is presented in this paper. These two degradation mechanisms deteriorate the oscillator's start-up reliability and the oscillation frequency by threshold voltage (V_th) degradation. According to impact analysis, an improved ring oscillator is proposed which is insensitive to degradation. The SPICE simulation shows that the oscillator has better start-up reliability and frequency stability.