Design of 8-bit Thermal-to-Digital Converter in CMOS Technology

• Main Authors: Chien, Ming-Cheng, 簡銘成
• Other Authors: Ker, Ming-Dou
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/64640178483054230715

碩士 === 國立交通大學 === 電子工程系 === 89 === In this thesis, a “Thermal-to-Digital Converter” (or call as “Temperature Sensor”) in CMOS technology has been designed by using the BJT device as the basic thermal detector. The ambient temperature is detected by this thermal-to-digital converter, and presented by an 8-bit digital code in the two’s complement format. There are two main circuit blocks in this 8-bit thermal-to-digital converter. One is the front part composed of an element of the thermal sensor and some amplifiers to enlarge the value of the detected voltage for feeding into the rear part. The other is the rear part which is a sigma-delta ADC to convert the detected analog voltage into an 8-bit digital code. Usually, there is an offset problem in CMOS analog or mixed-signal IC design. In this thesis, a method called as error bit compensation is developed to calibrate such error. By using this method, the offset generated from the process variation in the semiconductor circuit can be compensated. A test chip for this proposed thermal-to-digital converter has been fabricated in TSMC 0.35 μm 1P4M logic silicide 3.3 V CMOS process. From Hspice simulation and experimental results, the proposed thermal-to-digital converter can convert the temperature from -20 to +125 ºC into a 8-bit digital code.