Yang Wendi, Jiang Hanjun, Wang Zhihua
Institute of Microelectronics, Tsinghua University, Beijing 100084, China.
Sensors (Basel). 2019 Apr 13;19(8):1777. doi: 10.3390/s19081777.
This work presents a complementary metal-oxide-semiconductor (CMOS) ultra-low power temperature sensor chip for cold chain applications with temperatures down to -60 °C. The sensor chip is composed of a temperature-to-current converter to generate a current proportional to the absolute temperature (PTAT), a current controlled oscillator to convert the current to a frequency signal, and a counter as the frequency-to-digital converter. Unlike the conventional linear error calibration method, the nonlinear error of the PTAT current under the low temperature range is fully characterized based on the device model files provided by the foundry. Simulation has been performed, which clearly shows the nonlinear model is much more accurate than the linear model. A nonlinear error calibration method, which requires only two-point calibration, is then proposed. The temperature sensor chip has been designed and fabricated in a 0.13 μm CMOS process, with a total active die area of 0.0014 mm. The sensor only draws a 140 nA current from a 1.1 V supply, with the key transistors working in the deep subthreshold region. Measurement results show that the proposed nonlinear calibration can decrease the measurement error from -0.9 to +1.1 °C for the measurement range of -60 to +40 °C, in comparison with the error of -1.8 to +5.3 °C using the conventional linear error calibration.
本文介绍了一种用于冷链应用的互补金属氧化物半导体（CMOS）超低功耗温度传感器芯片，其温度范围可达-60°C。该传感器芯片由一个温度-电流转换器组成，用于产生与绝对温度（PTAT）成比例的电流；一个电流控制振荡器，用于将电流转换为频率信号；以及一个计数器作为频率-数字转换器。与传统的线性误差校准方法不同，基于代工厂提供的器件模型文件，对低温范围内PTAT电流的非线性误差进行了全面表征。进行了仿真，结果清楚地表明非线性模型比线性模型精确得多。随后提出了一种仅需两点校准的非线性误差校准方法。该温度传感器芯片采用0.13μm CMOS工艺设计并制造，总有源芯片面积为0.0014mm²。该传感器从1.1V电源仅汲取140nA电流，关键晶体管工作在深亚阈值区域。测量结果表明，与使用传统线性误差校准的-1.8至+5.3°C的误差相比，所提出的非线性校准在-60至+40°C的测量范围内可将测量误差从-0.9降低至+1.1°C。
