溫度感測與體溫開關整合晶片設計

Integrated Chip Design for Temperature Sensor and Body Temperature Switch

王建昇(Chien-Sheng Wang)

指導教授 ： 林進燈

國立交通大學/電機學院/電機學院IC設計產業專班/碩士(2009年)

https://doi.org/10.6842/NCTU.2009.00069

摘要

近年來，生醫訊號擷取與分析系統大多朝向可攜式研究為目標。採用電池安裝啟動之方式，目的是增加使用之可攜性與便利性。由於人體體溫相對於腦波與心跳是相當明顯的生理訊號，為了讓可攜式裝置能達到自動啟動及停止之動作，本論文將利用溫度晶片整合於可攜式生醫系統控制電源開關動作，更能達到系統晶片與可攜式生醫系統整合。
一般數位溫度感測系統包括前端的溫度感測電路及能帶隙參考電壓源，與後端的類比數位轉換電路，本論文基於基體推動（bulk driven）技術設計，達到低輸入電壓、低消耗功率之效果，並整合了溫度顯示及溫度開關電路。(1) 溫度開關是利用PMOS當主動負載將能帶隙參考電壓分壓，與溫度感測電路產生的電壓在30℃時經過比較電路控制MOSFET開關，MOSFET與後端偏壓電路連接，以控制MOSFET開與關，即控制後端電路動作與不動作之切換。(2) 溫度顯示是將溫度感測電路利用反相放大器調整電壓及線性度，達到足夠的解析度，以供外接的ADC使用。(3) 能帶隙參考電壓設計為0.75V，是為了之後將ADC整合在晶片內所預留，在此範圍主要是能得到較佳的感測準確度。
本論文的晶片設計使用台積電0.18um 1P6M CMOS的標準製程參數，模擬 -10℃～80℃溫度範圍內，所設計的電路正比於溫度變化的電壓值，電壓隨溫度變化率為2.25 mV/℃，能帶隙參考電壓為0.75V。

關鍵字

基體推動 ； 能帶隙參考 ； 正比於絕對溫度

並列摘要

Most of the portable devices for biomedical are starting by the installation of battery. In recent years, with the evolution of manufacturing process and microelectronic technology, the chip is easier to integrate with the portable biomedical system. For the convenience, we want to siwich the system by temperature. Because the human body temperature is a very clear physiological signal compared with the brain waves and heart rate, this thesis integrate the temperature circuit into the biomediacal system used for a switch.
A traditional digital temperature sensor system is composed of a temperature sensor in the front-end design and an analog to digital converter (ADC) in the back-end design. To reach the effect of low input voltage and low power consumption, this thesis uses the bulk driven technology. Moreover, the functions of temperature display and the temperature switch are also integrated into the design. The proposed design has three features as follows. (1) The temperature switch uses PMOS as active load to divide the bandgap voltage. The divided voltage will compare with the voltage of temperature sensor at 30℃ to control MOSFET connected with the bias circuit in the back-end design. (2) Temperature display is that the temperature sensor uses the inverting amplifier to adjust the voltage and linearity and to achieve sufficient resolution for the external ADC. (3) The bandgap reference voltage is designed as 0.75V. This can be integrated with ADC in the future and can get better sensor accuracy.
In this thesis, the proposed chip design is implemented by TSMC 0.18um 1P6M CMOS standard process parameters and is simulated in the temperature range from -10℃ to 80℃. Especially, the circuit voltage is proportional to temperature. This means that the voltage increases 2.25mV when temperature rises by 1℃. The bandgap reference voltage is designed as 0.75V.

並列關鍵字

bulk driven ； bandgap Reference ； Proportional To Absolute Temperature

參考文獻

[2]A. Bakker, J.H. Huijsing, "Micropower CMOS temperature sensor with digital output, "IEEE Journal of Solid-State Circuits, vol.31,Issue:7, pp.933-937, July 1996.

[3]E. A. Vittoz, "A low-voltage CMOS bandgap reference, "IEEE J. Solid- State Circuits, vol.SC-14, pp.573-577, 1979.

[4]R. L. Geiger, P. E. Allen, N. R. Strader, VLSI Design Techniques for Analog and Digital Circuits,McGraw-Hill, 1990.

[8]Sanduleanu, M.A.T.; Van Tuijl, A.J.M.; Wassenaar,.R.F. , "Accurate low power bandgap voltage reference in 0.5um CMOS technology, " Electronics Letters, Vol. 3410 , pp.1025 -1026, 1998.

[12]Blalock B J ,Allen P E. , "Designing 12V op amps using standard digital CMOS technology, " IEEE Trans Circuits and System Ⅱ:Analog and Digital Signal Processing ,1998.