隨著科技突飛猛進，現今製程演進之速度亦復如此，超大型積體電路的密度與用途變得越來越密集且廣闊，此時因電路密集度提高導致產生熱能的問題也隨之而來，如不仔細處理可能會使得電路元件被破壞而影響整個系統的安全性，也會導致後續處理問題的成本增加。為了降低溫度變化對電路造成的影響，在超大型積體電路裡面內建溫度感測器來監控晶片溫度的變化，可以增加系統的可靠性及使用時間，但積體式溫度感測器最難以克服的問題就是製程上面所帶來的變異。
本論文提出一種CMOS積體式時域智慧型溫度感測器，不僅功耗低，且可抵抗製程變異以及隨機不匹配所產生的誤差。主要感溫架構為差動對環形振盪器，此組環形振盪器可以振盪出與溫度成正比之溫敏脈衝寬度，並可利用製程校正單元進行製程上之變異校正，最後再藉由時間至數位轉換器轉換出相對應之數位輸出。於電路上利用蒙地卡羅分析出最佳面積配比及使用多重元件佈局技巧以降低製程上的隨機與系統誤差。
本溫度感測晶片使用TSMC 0.18-μm CMOS標準製程實現，操作速度高達431k S/s且每次轉換功耗僅需301pJ，操作電壓為類比區塊1.8V數位區塊0.9V，晶片核心面積為0.285mm2，解析度為0.48°C，且量測誤差經單點校正可在±0.6C內，經批次校正可在±1.5C內。目前本論文電路架構已被業界廠商相中，已進行產學合作，可見本論文之電路架構極具商業價值與競爭力。

With the advance of science and technology, the process technology becomes better than before. As the VLSI chips pursue high integration density and more functionalities, thermal effect becomes very important problems for chip design nowadays. Without proper supervision, the heat built up by undue power consumption may seriously damage the device robustness or even burn out the chip. To reduce the risk of overheating, VLSI chips gradually integrate temperature sensors for thermal monitoring to enhance their reliability and life span. But the process variation is still a big trouble for VLSI temperature sensor.
This paper presents a CMOS time-domain smart temperature sensor with low power consumption and the capability to reduce the impact caused by both process variation and random mismatch for mass production cost saving. A differential ring oscillator designed as the temperature sensing core generates a thermally sensitive output pulse with a width linearly proportional to the test temperature. A calibration circuit is utilized to eliminate the inaccuracy caused by process variation. A succeeding TDC is used for output coding. The Monte Carlo analysis is adopted to allocate areas for critical devices to fit the maximum random mismatch to the required accuracy. Furthermore, the systematic mismatch is carefully taken care of by precision layout.
Fabricated in a TSMC 0.18-μm standard CMOS process, the proposed sensor is able to operate at a high speed of 431k Samples/sec. Moreover, each sample consumes only 301pJ at 1.8V/0.9V operation voltage for analog/digital circuit. The core area is merely 0.285mm2, the resolution is 0.48°C, and the inaccuracy is measured to be ±0.6C by one-point calibration and ±1.5C by batch-calibration in a wide temperature range of 0C to 120C. This proposed sensor functions well and is currently licensed by Actron Technology Corporation through an academia and industry cooperation. The commercial value and the competitiveness of the proposed sensor is thus convinced.

[1] 盧明智、盧鵬任 編著，感測器應用與線路分析，台北：全華出版公司，2000。
[2] R. Achenbach, M. Feuerstack-Raible, F. Hiller, M. Keller, K. Meier, H. Rudolph, R. Saur-Brosch, “A digitally temperature-compensated crystal oscillator,” IEEE Journal of Solid-State Circuits, vol. 35, no. 10, pp. 1502-1506, Oct. 2000.
[3] C. Poirier, R. McGowen, C. Bostak, S. Naffziger, “Power and temperature control on a 90nm Itanium®-family processor,” IEEE International Solid-State Circuits Conference, pp. 304-305, Feb. 2005.
[4] C. Park, H. Chung, Y. S. Lee, J. Kim, J. Lee, M. S. Chae, D. H. Jung, S. H. Choi, S. Y. Seo, T. S. Park, J. H. Shin, J. H. Cho, S. Lee, K. W. Song, K. H. Kim, J. B. Lee, C. Kim, S. I. Cho, “A 512-mb DDR3 SDRAM prototype with CIO minimization and self-calibration techniques,” IEEE Journal of Solid-State Circuits, vol. 41, no. 4, pp. 831-838, Apr. 2006.
[5] C. Park, H. Chung, Y. S. Lee, J. Kim, J. Lee, M. S. Chae, D. H. Jung, S. H. Choi, S. Y. Seo, T. S. Park, J. H. Shin, J. H. Cho, S. Lee, K. Kim, J. B. Lee, C. Kim, S. I. Cho, “A 512Mbit, 1.6Gbps/pin DDR3 SDRAM prototype with C10 minimization and self-calibration techniques,” IEEE Symposium on VLSI Circuits, pp. 370-373, Jun. 2005.
[6] A. Bakker and J. H. Huijsing, High-Accuracy CMOS Smart Temperature Sensors. Boston:Kluwer Academic Publishers, 2000.
[7] G. C. M. Meijer, G. Wang, and F. Fruett, “Temperature sensors and voltage references implemented in CMOS technology,” IEEE Sensors Journal., vol. 1, no. 3, pp. 225–234, Oct. 2001.
[8] A. Bakker and J. H. Huijsing, “Micropower CMOS temperature sensor with digital output,” IEEE Journal of Solid-State Circuits, vol. 31, no. 7, pp. 933-937, Jul. 1996.
[9] M. Tuthill, “A switched-current, switched-capacitor temperature-sensor in 0.6-µm CMOS,” IEEE Journal of Solid-State Circuits, vol. 33, no. 7, pp. 1117-1122, Jul. 1998.
[10] E. Rotem, A. Naveh, et al., “Analysis of Thermal Monitor features of the Intel Pentium M Processor,” Proceedings of TACS-01, ISCA-31, 2004.
[11] P. Chen, C. C. Chen, C. C. Tsai, W. F. Lu, “A Time-to-Digital-Converter-Based CMOS Smart Temperature Sensor,” IEEE Journal of Solid-State Circuits, vol. 40, no. 8, pp. 1642-1648, Aug. 2005.
[12] T. A. Demassa and Z. Ciccone, Digital Integrated Circuits. New York: Wiley, 1996.
[13] K. Kim, H. Lee, S. Jung and C. Kim, “A 366kS/s 400uW 0.0013mm2 Frequency-to-Digital Converter Based CMOS Temperature Sensor Utilizing Multiphase Clock” IEEE Custom Integrated Circuits Conf., pp. 203-206, Sep. 2009.
[14] P. Krummenacher and H. Oguey, “Smart temperature sensor in CMOS technology,” Sensors and Actuators, A21-A23, pp. 636-638, 1990.
[15] A. Bakker, “CMOS smart temperature sensors-an Overview,” Proc. IEEE Sensors, vol. 2, pp. 1423-1427, Jun. 2002.
[16] K. E. Kuijk, “A precision reference voltage source,” IEEE Journal of Solid-State Circuits, vol. 8, no. 3, pp. 222-226, Jun. 1973.
[17] D. Hilbiber, “A New Semiconductor Voltage Standard” ISSCC Dig. of Tech. Paper, pp. 32-33, Feb. 1964
[18] B. Razavi, Design of Analog CMOS Integrated Circuits. New York: McGraw-Hill, 2001.
[19] R. Widlar, “New developments in IC voltage regulators,” IEEE International Solid-State Circuits Conference, pp. 158-159, Feb. 1970.
[20] S. J. Chang, Advanced analog IC design, EE, NCKU, 2003.
[21] K. Souri, Y. Chae, and K. Makinwa, “A CMOS Temperature Sensor With a Voltage-Calibrated Inaccuracy of 0.15°C (3σ) From -55°C to 125°C” IEEE Journal of Solid-State Circuits, vol. 48, no. 1, pp. 292-301, Jan. 2013.
[22] M. Sasaki, M. Ikeda and K. Asada. “A Temperature sensor with an inaccuracy of -1/+0.8°C using 90-nm 1-V CMOS for online thermal monitoring of VLSI circuits,” IEEE Transaction on Semiconductor Manufacturing. vol. 21, pp. 201 - 208, May. 2008.
[23] I. M. Filanovsky and A. Allam, “Mutual compensation of mobility and threshold voltage temperature effects with applications in CMOS circuits,” IEEE Transactions on Circuits and Systems I, vol. 48, no. 7, pp. 876–884, Jul. 2001.
[24] K. Arabi and B. Kaminska, “Built-in temperature sensors for on-line thermal monitoring of microelectronic structures,” IEEE Computer Design: VLSI in Computers and Processors, pp. 462–467, Oct. 1997.
[25] P. Ituero, J. L. Ayala, M. Lopez-Vallejo, “Leakage-based On-Chip Thermal Sensor for CMOS Technology,” IEEE International Symposium on Circuits and Systems, pp. 3327-3330, 2007.
[26] P. E. Allen and D. R. Holberg, CMOS Analog Circuit Design. Oxford University Press, 2002.
[27] M. K. Law and A. Bermak, “A 405-nW CMOS Temperature Sensor Based on Linear MOS Operation,” IEEE Transactions on Circuits and Systems II, vol. 56, no. 12, pp. 891–895, Dec. 2009.
[28] M. A. P. Pertijs, K. Makinwa and J. H. Huijsing, “A CMOS Smart Temperature Sensor With a 3σ Inaccuracy of 0.1 °C From 55 °C to 125 °C,” IEEE Journal of Solid-State Circuits, vol. 40, no. 12, pp. 2805-2815, Dec. 2005.
[29] A. L. Aita, M. Pertijs, K. Makinwa, J. H. Huijsing, “A CMOS Smart Temperature Sensor with a Batch-Calibrated Inaccuracy of ±0.25°C (3σ) from -70°C to 130°C,” IEEE International Solid-State Circuits Conference, pp. 342-343, Feb. 2009.
[30] F. Sebastiano, L. J. Breems, K. A. A. Makinwa, S. Drago, D. M. W. Leenaerts, B. Nauta, “A 1.2V 10μW NPN-Based Temperature Sensor in 65nm CMOS with an Inaccuracy of ±0.2°C (3σ) from –70°C to 125°C,” IEEE International Solid-State Circuits Conference, pp. 312-313, Feb. 2010.
[31] C. K. Kim, B. S. Kong, C. G. Lee, Y. H. Jun, “ CMOS Temperature Sensor with Ring Oscillator for Mobile DRAM Self-refresh Control,” IEEE International Symposium on Circuits and Systems, pp. 3094-3097, May. 2008.
[32] Y. Ren, C. Wang, H. Hong, “An all CMOS temperature sensor for thermal monitoring of VLSI circuits,” IEEE Circuits and Systems International Conference on Testing and Diagnosis, pp. 1-5, Apr. 2009.
[33] S. Hwang et al., “A 0.008 mm2 500uW 469kS/s Frequency-to-Digital Converter Based CMOS Temperature Sensor With Process Variation Compensation,” IEEE Trans. Circuits Syst. I, Reg. Papers vol. 60, no. 9, pp. 2241–2248, Sept. 2013
[34] I. M. Filanovsky and A. Allam, “Mutual compensation of mobility and threshold voltage temperature effects with applications in CMOS circuit,” IEEE TCAS-I, vol. 48, NO. 7, pp. 876-884, Jul. 2001.
[35] Y. Tsivids, Operation and modeling of the MOS transistor, New York: McGraw-Hill, 1988.
[36] S. Mohamad, F. Tang, A. Amira, A. Bermak, M. Benammar, “A Low Power Oscillator Based Temperature Sensor for RFID Applications,” IEEE 5th Asia Symposiun on Quality Electronic Design.
[37] Y. An, K. Ryu, D. Jung, S. Woo S. Yung, “An Energy Efficient Time-Domain Temperature Sensor for Low-Power On-Chip Thermal Management,” IEEE SENSORS JOURNAL, vol. 14, NO. 1, Jan. 2014.
[38] R. Nutt, “Digital Time Intervalometer,” Rev. Sci. Instrum, vol. 39, no. 9, pp. 1342-1345, Sep. 1968.
[39] P. Dudek, S. Szczepancki and J.V. Hatfield, “A high-resolution CMOS time-to-digital converter utilizing a Vernier delay line” IEEE Journal of Solid-State Circuits, vol. 35, no. 2, pp. 240-247, Feb. 2000.
[40] E. Raisanen-Ruotsalainen, T. Rahkonen, J. Kostamovaara, “A low-power CMOS time-to-digital converter,” IEEE Journal of Solid-State Circuits, vol. 30, no. 9, pp. 984-990, Sep. 1995
[41] J. Yuan and C. Svensson, “High-speed CMOS circuit technique,” IEEE Journal of Solid-State Circuits, vol. 24, no. 1, pp. 62-70, Feb. 1989.
[42] A. Hastings, The art of analog layout, Prentice Hall, 2001.
[43] M. J. M. Pelgrom, A. C. J. Duinmaijer, and A. P. G. Welbers, “Matching properties of MOS transistors,” IEEE Journal of Solid-State Circuits, vol. 24, pp. 1433–1440, May 1989.
[44] X. Dai, C. He, H. Xing, D. Chen, and R. Geiger, “An Nth order central symmetrical layout pattern for nonlinear gradients cancellation,” in Proc. IEEE International Symposium Circuits system., pp. 4835–4838, May 2005
[45] S. Jeong, Z. Foo, Y. Lee, J. Y. Sim, D. Blaauw, D. Sylvester, “A Fully-Integrated 71 nW CMOS Temperature Sensor for Low Power Wireless Sensor Nodes,” IEEE Journal of Solid-State Circuits, vol. 49, no. 8, pp. 1682-1693, August. 2014.
[46] X. Tang, K.P. Pun, W.T. Ng, “A 0.9V 5kS/s resistor-based time-domain temperature sensor in 90nm CMOS with calibrated inaccuracy of −0.6°C/0.8°C from −40°C to 125°C,” Solid-State Circuits Conference, 2013 IEEE Asian, pp. 169 - 172, 11-13 Nov. 2013.
[47] G. Chowdhury and A. Hassibi, “An On-Chip Temperature Sensor With a Self-Discharging Diode in 32-nm SOI CMOS,” IEEE Transactions on Circuits and Systems II, vol. 59, no. 9, pp. 568–572, Sep. 2012.
[48] P. Chen, C. C. Chen, Y. H. Peng, K. M. Wang, Y. S. Wang, “A Time-Domain SAR Smart Temperature Sensor With Curvature Compensation and a 3σ Inaccuracy of -0.4°C ~ +0.6°C Over a 0 °C to 90 °C Range,” IEEE Journal of Solid-State Circuits, vol. 45, no. 3, pp. 600-609, Mar. 2010.
[49] D. D. Venuto and E. Stikvoort, “Low-Power CMOS Smart Temperature Sensor With a Batch-Calibrated Inaccuracy of ±0.25°C (±3σ) from −70°C to 130°C,” IEEE Sensors Journal., vol. 13, no. 5, pp. 1840-1848, May. 2013.
[50] K. Souri, and K. Makinwa, “A 0.12 mm2 7.4 µW Micropower Temperature Sensor With an Inaccuracy of ±0.2°C (3σ) From -30°C to 125°C” IEEE Journal of Solid-State Circuits, vol. 46, no. 7, pp 1693-1700, July 2011.
[51] C. K. Wu, W. S. Chan and T. H. Lin, “A 80kS/s 36uW resistor-based temperature sensorusing BGR-free SAR ADC with a unevenly-weighted resistor string in 0.18um CMOS,” IEEE Symposium on VLSI Circuits, pp. 222–223, Jun. 2011