The　clock　signal　is　a　critical　factor　for　digital　circuits.　However,　during　the　chip　manufacturing　process,　variations　in　conditions　such　as　power　supply　voltage,　process,　temperature,　and　more　can　lead　to　deviations　in　oscillators　frequency　compared　to　the　design　specifications,　the　value　may　even　reach　a　variation　range　of　±　35%,　which　potentially　impact　the　functionality　and　performance　of　the　chip.　In　order　to　compensate　the　influence　of　these　non-ideal　factors　on　the　oscillator　frequency.　An　on-chip　fast　digital　automatic　calibration　with　Successive　Approximation　Register　(SAR)　logic　is　proposed,　compared　with　the　traditional　logic　of　calibration　by　addition　and　subtraction,　the　proposed　circuit　can　exhibit　high　calibration　speed.　8-bit　control　word　on-chip　fast　digital　automatic　calibration　module　of　proposed　is　designed　in　TSMC　180nm　process,　and　the　proposed　calibration　scheme　has　been　applied　to　the　actual　chip　to　verify　the　reliability　of　the　designed　scheme,　which　has　an　important　impact　on　the　use　of　the　internal　clock　of　the　chip.　©　2023　IEEE.