An NBTI-Aware Digital Low-Dropout Regulator with Adaptive Gain Scaling Control

Digital low-dropout voltage regulators (DLDOs) have drawn increasing attention for the easy implementation within nanoscale devices. Despite their various benefits over analog LDOs, disadvantages may arise in the form of negative bias temperature instability (NBTI) induced performance degradation. In this paper, a simple and effective adaptive gain scaling (AGS) technique with a steady-state capture feature is proposed. AGS senses the steady-state output of a DLDO and reduces the gain to the minimum value to obtain a stable output voltage. Moreover, a novel uni-directional barrel shifter is proposed to reduce the aging effect of the DLDO. This uni-directional barrel shifter evenly distributes the load among DLDO output stages to obtain a longer lifetime. The benefits of the proposed techniques are explored and highlighted through extensive simulations. The proposed techniques also have negligible power and area overhead. NBTI-aware design with AGS can reduce the transient response time by 59.5% as compared to aging unaware conventional DLDO and can mitigate the aging effect up to 33%.