标题: 应用于冷链物流之环境感测器读出电路设计与实现
The Environmental Sensor Readout Circuit and its Applications to Cold Chain Logistics
作者: 贺子诚
Ho, Zih-Cheng
张锡嘉
Chang, Hsie-Chia
电子工程学系 电子研究所
关键字: 感测器;差动感测;单端感测;湿度计;加速度计;微机电;MEMS Sensor;Differential Sensing;Single-ended Sensing;Humidity Sensor;Accelerometer;MEMS
公开日期: 2013
摘要: 在本篇论文中,我们使用时脉-数位转换器(TDC)分别实践于两种不同的读出电路。相对于传统的类比-数位转换器,我们先将类比讯号转换成时脉,进而直接转换成数位码读出。第一种TDC的实现电路为差动式电容转数位读出电路。差动式读出电路只会转换差模电容之间的变异情形,而可直接忽略双端共模电容的变化。另一种TDC的实现电路为应用在单端输出感测器的双延迟锁相回路式(dual-DLL)时脉转数位读出电路。这类单端输出感测器具有较大的寄生电容,因此dual-DLL读出电路补偿了寄生电容,并藉由自动矫正机制来增加感测范围。在电路的应用上,分别针对不同的环境感测器,我们的差动式电容转数位读出电路可适用在双端差动指叉电容式加速度感测器,而dual-DLL时脉转数位读出电路则可适用在单端感测器,例如:湿度计与温度计。从晶片的量测结果中可得到,我们所设计的差动式读出电路以单轴加速度为例,可操作在125K赫兹的取样频率下,可分辨出80个层级共±8g的加速度差异,并且消耗约50uW的功率。我们使用的是联电0.18μm CMOS制程。另外在湿度计的量测中,在操作模式下有52μW的功率消耗,而在休眠模式下则只有13μW的功率消耗。我们所使用的取样频率为8K赫兹以及使用台积电0.35μm CMOS制程。由量测结果可显示,本论文所提出的电路具有低功耗与高解析等优点。
In this thesis, we present two types of readout circuits by using time-to-digital convertors (TDC). In contrast to traditional analog-to-digital converter (ADC), our approach converts the analog signal into the time pulse, and directly outputs the digital code without the voltage-to-digital or current-to-digital converter. The first type of TDCs is the differential capacitance-to-digital readout circuit. The differential readout circuit only converts the variation of differential capacitance and ignores the common-mode capacitance. Another type of TDCs is dual-DLL time-to-digital readout circuit. This circuit is used to the sensors with single-ended output. These sensors have large parasitic capacitances, and this readout circuit can compensate the parasitic capacitance and increase the sensing range with an auto-trimming mechanism. To implement the environmental sensor with our readout circuits, the differential capacitance-to-digital readout circuit is used in an accelerometer with differential finger-type electrodes. And dual-DLL time-to-digital readout circuit is used in the single-ended output sensors, humidity sensor and temperature sensors. From chip measurement results, our accelerometer can differentiate the 80-level accelerations between ±8g, and just consumes around 50uW for 1-axis, 82uW for 3-axis under 125KHz of sampling frequency with 1.8v of supply voltage. The humidity sensor is 52uW in the operating mode, and 13uW in the sleeping mode under 8KHz of sampling frequency with 1.3v of supply voltage.
URI: http://140.113.39.130/cdrfb3/record/nctu/#GT070050248
http://hdl.handle.net/11536/73510
显示于类别:Thesis