This　paper　presents　a　precision　CMOS　temperature-to-digital　converter　(TDC),　which　sensing　the　temperature-dependent　base-emitter　voltage　of　substrate　PNPs.　The　TDC　is　applied　to　temperature　compensation　of　FBAR　oscillator.　The　proposed　TDC　adopts　the　bipolar　transistors　as　the　core　device,　and　use　Zoom　analog-to-digital　converter　(Zoom　ADC)　to　read　temperature　information.　The　PTAT　bias　circuit　is　used　in　the　temperature　frontend　to　correct　the　nonlinearity　of　the　V　{B　E}.　The　mismatch　of　current　sources　and　the　offset　of　operational　amplifiers　are　reduced　by　dynamically　element　matched　(DEM)　and　chopping　techniques,　respectively.　With　these　techniques,　the　current　gain　beta　{F}　of　BJT　is　compensated　and　the　accuracy　of　circuit　is　improved.　The　Zoom　ADC　is　composed　of　SAR　ADC　and　Sigma-Delta　ADC.　The　SAR　ADC　is　used　to　complete　rough　quantization　and　narrow　the　quantization　interval,　meanwhile,　the　fine　quantization　is　realized　by　Sigma-Delta　ADC.　By　this　method,　Zoom　ADC　takes　full　advantages　of　the　fast　speed　of　the　SAR　ADC　and　the　high　accuracy　of　the　Sigma-Delta　ADC,　which　significantly　reduces　the　ENOB　requirement　for　the　Sigma-Delta　ADC　and　design　difficulty.　The　control　clock　circuit　of　the　ADC　is　integrated　in　the　circuit　to　simplify　system　application.　This　circuit　is　designed　in　TSMC　0.18　mu　mathrm{m}　CMOS　processes.　The　simulation　results　show　that　the　static　current　of　the　circuit　is　131　mu　mathrm{A}left(text{@}　27{circ}　mathrm{C}right)　under　the　supply　voltage　of　1.8　V.　After　two-point　calibration　correction,　the　temperature　measurement　accuracy　achieved　pm　0.5{circ}　text{C}　in　the　range　of-55{circ}　text{C}　sim　125{circ}　text{C}.　The　core　area　of　the　circuit　is　560　mu　m　times　330　mu　m.　©　2021　IEEE.