Physically Unclonable Functions (PUFs) have become a promising low-cost solution for authentication and key generation in cryptosystems. However, it has been shown in the literature that the reliability of PUFs is undermined by aging mechanisms, such as Bias Temperature Instability (BTI), which may compromise their correct operation. In this paper, we present a novel ring oscillator (RO) based PUF design that is robust against BTI degradation, hereinafter referred to as Low-sensitive-BTI RO - LBTIRO. We compare our proposed LBTIRO to the standard RO-based PUF and to an alternative NBTI-robust RO-PUF recently presented in the literature, for 90 nm and 32 nm CMOS technology nodes. We show that, for considered technology nodes, our proposed LBTIRO features a higher robustness against BTI. Particularly, our LBTIRO enables a reduction of the impact of BTI on the oscillation frequency over circuit lifetime, which reaches 85.3% and 72.1% against the standard RO and the recent alternate solution, respectively, for the 90 nm technology. Moreover, we show that our proposed LBTIRO features a reduction in terms of power consumption if compared to the alternative NBTIrobust RO-PUF.

This paper presents a synthetic overview of multilevel (ML) flash memory program methods. The problem of increasing program time with the number of bits stored in each cell is discussed and methods based on both channel hot electrons (CHE) and Fowler-Nordheim tunneling (FNT) are discussed. In the case of CHE, the use of an increasing voltage rather than a constant one on the control gate (CG) leads to narrower threshold voltage distributions and smaller current absorption, with positive effects on the degree of parallelism and program throughput. As for FNT, much faster programming than that commonly used today can be done using high CG voltages without producing intolerable degradation of cell reliability.