The　ring-oscillator　physical　unclonable　function　(RO　PUF)　is　easily　affected　by　the　ambient　temperature.　As　the　temperature　increases,　the　frequency　of　the　ring　oscillator　changes,　causing　the　ROPUF　to　output　error　response　bits.　We　studied　the　temperature　variation　characteristics　of　the　RO　PUF　relating　to　reliability,　investigating　the　reasons　for　the　low　reliability　of　the　RO　PUF　due　to　temperature　effects　from　the　perspective　of　MOSFET　temperature　characteristics,　without　changing　the　original　circuit　structure　of　the　RO　PUF.　In　the　55nm　process,　Cadence　and　Monte　Carlo　simulations　were　used　to　reveal　how　changes　in　MOSFET　threshold　voltage　affect　RO　PUF　temperature　characteristics.　On　the　above　basis,　a　method　that　optimizes　the　temperature　reliability　of　RO　PUF　circuits　from　MOSFET　temperature　characteristics　was　studied.　©　2025　SPIE.