US Patent 11233663 Physically unclonable function having source bias transistors

A physically unclonable function (PUF) includes an array of differential PUF bits arranged in rows and columns, wherein each differential bit is located at an intersection of a row and a column, and includes a first PUF cell coupled to a corresponding first bit line and first source line and a second PUF cell coupled to a corresponding second bit line and second source line. The PUF includes a source bias transistor coupled between each corresponding first source line and a first power supply terminal and between each corresponding second source line and the first power supply terminal, wherein a gate electrode of each of the source bias transistors is coupled to a second power supply terminal, and a corresponding set of margin transistors coupled in parallel with each source bias transistor, wherein a gate electrode of each margin transistor is coupled to receive a corresponding margin setting control signal.