Disclosed is an input/output circuit for a physical unclonable function generator circuit. In one embodiment, a physical unclonable function (PUF) generator includes: a PUF cell array comprising a plurality of bit cells configured in a plurality of columns and at least one row, and at least one input/output (I/O) circuit each coupled to at least two neighboring columns of the PUF cell array, wherein the at least one I/O circuit each comprises a sense amplifier (SA) with no cross-coupled pair of transistors, wherein the SA comprises two cross-coupled inverters with no access transistor and a SA enable transistor, and wherein the at least one I/O circuit each is configured to access and determine logical states of at least two bit cells in the at least two neighboring columns; and based on the determined logical states of the plurality of bit cells, to generate a PUF signature.