Schmitt-Trigger Based Physically Unclonable Function with Variable Vt
Sesibhushana Rao Bommana, Sreehari Veeramachaneni, Srinivas MB · 2023
Physically Unclonable Function (PUF) is one of the key building blocks of hardware-based SoC security. PUF is the fingerprint of a System-on-Chip that exploits process variations in CMOS fabrication. This paper presents a Schmitt Trigger (ST) based physically unclonable function with a dynamic threshold voltage (DST PUF) that can provide better noise immunity across various process and temperature conditions leading to greater consistency for foolproof functionality. This paper proposes to replace the regular inverter and Schmitt trigger with a dynamically variable Vt Schmitt trigger inverter for the arbiter PUF circuit and verify the functionality and variations in delay. Also proposed is a method that varies Schmitt Trigger's hysteresis based on the host challenge and its effect on the delay variation. This approach adds additional randomness to the response to improve the Hamming Distance (HD) of the response from the PUF. The results are verified, and the standard deviation of the delay of DST PUF is more than 2.2 times and 1.2 times, respectively than the regular arbiter PUF and the ST PUF.