本論文提出一個基於環形振盪器的溫度感測架構和三角積分調變時間數位轉換器架構。
溫度感測器可以分為前端溫度感測電路和後端的讀出電路。電流控制振盪器(CCO) 作為溫度感測器前端的溫度感測電路，透過金氧半場效電晶體(MOS) 操作於次臨界區時對於溫度的特性，產生與溫度相關的電壓〖 V〗_CCO。並且利用回授網絡調節CCO的電流，使CCO能夠輸出穩定的時脈。其頻率不受到溫度影響，並且能夠供應給後級取樣電路做使用，同時運用開關式電阻的技巧縮小晶片面積；溫度感測器後端則是以充電幫浦作為第一級積分器;離散式開關式電容積分器作為第二級積分器的三角積分調變時間數位轉換器(DSM TDC)，TDC將溫度訊號V_CCO轉換為數位訊號。利用電壓時間轉換器(VTC)將電壓溫度訊號V_CCO轉換為時間溫度訊號∅_CCO。之後∅_CCO進行三角調變並透過時間數位轉換器產生相對應的數位訊號。
此論文使用台積電180 nm的互補式金屬氧化物半導體製程實現所提出之架構。佈局模擬輸入頻寬為250 Hz，取樣頻率為32 kHz，在超取樣比率為64的情況下，能夠達到解析度10.25 bits，解析度為0.08 ℃/LSB。晶片在-20 ℃~80 ℃量測中，溫度感測器工作於0.8 V，其功率消耗為1100 nW。溫度感測器輸出電壓VCCO能產生1.3 mV/℃的敏感度，振盪器頻率穩定度為2%在100 ℃的溫度範圍內。電壓電源變化400 mV時，頻率變化1.5%~1.2%左右。

This paper presents a temperature sensor based on a ring oscillator and a ΔΣ modulation time-to-digital converter (TDC). The temperature sensor consists of a front-end temperature sensing circuit and a back-end readout circuit. The front-end temperature sensing circuit employs a current-controlled oscillator (CCO) that operates in the subthreshold region of a metal-oxide-semiconductor (MOS) transistor to generate a temperature-dependent voltage, V_CCO. A feedback network is utilized to regulate the current of the CCO, ensuring a stable clock output. The CCO's frequency is not affected by temperature and can be supplied to the subsequent sampling circuit. The back-end of the temperature sensor employs a charging pump as the first integrator and a discrete-time switched-capacitor integrator as the second integrator in the ΔΣ modulation TDC. The TDC converts the temperature signal, V_CCO, into a digital signal. A voltage-to-time converter (VTC) is used to transform the voltage temperature signal, V_CCO, into a time-domain temperature signal, ∅_CCO. Subsequently, ∅_CCO undergoes triangle modulation and is converted into the corresponding digital signal by the time-to-digital converter.
The proposed architecture is implemented using a TSMC 180 nm complementary metal-oxide-semiconductor (CMOS) process. Post-layout simulations show that the architecture achieves a resolution of 10.25 bits with a input bandwidth of 250 Hz and a sampling frequency of 32 kHz, under an oversampling ratio of 64. The resolution corresponds to 0.08 ℃/LSB. During temperature measurements from -20 ℃ to 80 ℃, the temperature sensor operates at 0.8 V with a power consumption of 1.1μW. The temperature sensor's output voltage, VCCO, exhibits a sensitivity of 1.3 mV/℃, and the oscillator frequency stability is within 2% over a temperature range of 100 ℃. When the voltage power supply varies by 400 mV, the frequency variation is approximately 1.5% to 1.2%.

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