An All BTI (N-PBTI, N-NBTI, P-PBTI, P-NBTI) Odometer based on a Dual Power Rail Ring Oscillator Array

An on-chip reliability monitor capable of characterizing all four bias temperature instability (BTI) modes is proposed. Stressed ring oscillators with independent dual power rails are implemented in which odd and even stages of an inverter chain are subject to different stress voltage configurations. A beat frequency detection technique with 3 reference ring oscillators achieves a frequency measurement resolution as low as 0.01% with a short measurement interruption time of
$4\mu\mathrm{s}$
. Extensive BTI data collected from a 65nm ROSC array is presented for different stress conditions.