using soft-edge flip-flops to compensate nbti-induced delay degradation
We present a low-overhead solution to tackle the delay increase caused by Negative Bias Temperature Instability (NBTI), which has emerged as the most critical reliability issue in sub-90nm technology nodes. The proposed solution consists of using special type of registers, called soft-edge flip-flops (SEFFs), which allow to compensate for the delay increase by introducing a transparency window. SEFFs are an effective alternative to existing solutions such as threshold, supply, or body-bias voltage modulation, since they provide minimum area and power overhead, and can seamlessly replace regular FFs. Results show that delay degradation up-to 60ps after 10 years of aging can be accounted for with a very small (less than 1\%) area penalty.
flip-flop nbti seff setup and hold time circuit reliability device aging