本論文提出了超低轉換能量電阻式溫度感測器，透過不同電阻型態將外部環境溫度變化所造成的頻率差轉換成數訊號值供電腦儀器判讀。溫度感測部分主要由正溫度係數(Proportional To Absolute Temperature, PTAT)以及負溫度係數(Complementary To Absolute Temperature, CTAT)之環形振盪器所組成。透過正、負溫度係數的電阻使環形振盪器與環境溫度具有相關性。隨著環境溫度的變化，造成電阻值的改變，導致環形振盪器每一級延遲時間(Propagation Delay)的改變，影響環形振盪器之頻率。此設計把負溫度係數的環形振盪器透過計數器將頻率轉成數位訊號後，使其計數固定的周期數後產生停止轉換訊號(EOC)去紀錄PTAT計數器目前數到之數位碼，完成一次轉換；而正溫度係數的環形振盪器會透過分相式細級轉換電路，將一個周期的訊號均勻切成六等分，以提升溫度感測器之解析度。當停止轉換訊號從低轉為高時，PTAT計數器之數位碼會被記錄下來，做為待測溫度對應之數位輸出。為了要降低不同晶片間的誤差值，我們亦將CTAT計數器改成可編輯程式化的計數器，透過調整計數器所計數的週期數，將相同溫度之下，不同晶片的數位碼平移至相同的地方，達到單點校正的效果。
本論文的晶片實現於TSMC 0.18µm 1P6M製程，本電路之供應電壓為0.8V，並且將環形振盪器以及計數器之供應電壓分開擺設，PTAT環形振盪器在室溫(27℃)之操作頻率為12.4 MHz，CTAT環形振盪器則為26 MHz，核心電路所消耗功率為38.47 µW，轉換時間為51 µs，每次轉換所需的能量為1.96 nJ。溫度量測範圍為0°C~110°C，輸出之溫度值解析度為0.11°C。本研究之溫度感測器經單點校正後，其誤差值為+2.22℃/-2.06℃；經兩點校正加二次曲率修正後，其誤差值為+0.42°C/-0.42℃。本論文之FOMRES為0.024以及FOMACC為1.13，且晶片面積為0.285×0.234mm^2=0.067mm^2。

This thesis presents an ultra-low energy-per-conversion resistor-based temperature sensor that converts the frequency difference caused by test temperature into digital output. The temperature sensing part is mainly composed of a Proportional to Absolute Temperature (PTAT) ring oscillator and a Complementary to Absolute Temperature (CTAT) ring oscillator. By using PTAT and CTAT resistors in the ring oscillators, the circuit is sensitive to temperature variation. In this design, the CTAT ring oscillator counts a fixed number of cycles and then generates an End-of-Conversion (EOC) signal to record the current count of the PTAT counter. The PTAT ring oscillator, on the other hand, is divided into six equal phases per cycle through phase division to improve the resolution of the temperature sensor. When the EOC signal is triggered, the digital code of the PTAT counter is recorded as the digital output of the test temperature. In order to eliminate the process variation, the CTAT counter is modified to be programmable, allowing the CTAT counter to adjust the number of cycles so that the digital outputs of different chips under the same test temperature will be calibrated to be the same to achieve the so-called single-point calibration.
The designed chip is implemented in a TSMC 0.18µm CMOS standard process. The supply voltage of the whole circuit is 0.8V. The operating frequencies of the PTAT and CTAT ring oscillators at room temperature (27°C) are 12.4 and 26 MHz, respectively. The core circuit consumes 38.47 µW of power, with a conversion time of 51 µs and an energy consumption of 1.96 nJ per conversion. The temperature measurement range is 0°C~110°C, and the temperature resolution is 0.11°C. In this research, the integral nonlinearity error of this temperature sensor is +2.22℃/-2.06℃ with one-point calibration. On the other hand, the integral nonlinearity error of this temperature sensor is +0.42°C/-0.42℃ with two-point calibration and 2nd curvature correction. The FOMRES of this proposed sensor is 0.024, and the FOMACC is 1.13. The chip area is 0.285×0.234mm^2=0.067mm^2.

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