Alleviating NBTI-induced failure in off-chip output drivers

Abstract

Negative Bias Temperature Instability (NBTI) causes the threshold voltage of PMOS devices to degrade with time, resulting in a reduced lifetime of a CMOS IC. In this paper, we present an approach to mitigate the degradation due to NBTI for off-chip output drivers. Our approach is based on forcibly inducing relaxation in the individual fingers of the output driver (which is typically implemented in a multi-fingered fashion). The individual fingers are relaxed in a round-robin manner, such that at any given time, k out of n fingers of the driver are being relaxed. Our results show that the proposed approach significantly extends the lifetime of the output driver.