An FPGA Chip Identification Generator Using Configurable Ring Oscillators

Physically unclonable functions (PUF) are commonly used in applications such as hardware security and intellectual property protection. Various PUF implementation techniques have been proposed to translate chip-specific variations into a unique binary string. It is difficult to maintain repeatability of chip ID generation, especially over a wide range of operating conditions. To address this problem, we propose utilizing configurable ring oscillators and an orthogonal re-initialization scheme to improve repeatability. An implementation on a Xilinx Spartan-3e field-programmable gate array was tested on nine different chips. Experimental results show that the bit flip rate is reduced from 1.5% to approximately 0 at a fixed supply voltage and room temperature. Over a 20 ^°C-80 ^°C temperature range and 25% variation in supply voltage, the bit flip rate is reduced from 1.56% to 3.125×10^-7.