Physically unclonable function and method for generating a digital code

Abstract

A physically unclonable function (PUF) is implemented using a PUF array of single-transistor cells organized as a plurality of word lines and intersecting bit lines. A single-transistor cell is connected to a word line and bit line at each of the intersections. A current source is coupled to each of the bit lines and provides a current when a PUF cell connected to the bit line is conductive. The bit lines are organized in pairs. A PUF evaluation engine is coupled to the PUF array and provides an address for selecting a word line of the PUF array in response to a challenge. A comparator is coupled to each pair of bit lines of the PUF array for detecting a current. The comparator provides a voltage signal in response to detecting a difference current between the first and second bit line. The PUF evaluation engine receives the voltage signal and generates a logic bit.