The Analog and Mixed-signal IP team of ASIC & SYSTEM Department of Institute of Microelectronics of Chinese Academy of Sciences (IMECAS) recently completed a thermopile analog front-end and high precision temperature sensor chip test in “SoC for Thermopile” project. The results showed that, the chip had reached a high level on function and performance.
Researchers in IMECAS successfully developed high precision temperature sensor chip with low noise and low offset analog front-end. With the chopper technology of low noise, low offset operational amplifier and high precision Sigma-Delta converter, the ENoB(Effective number of bits) of the chip can reach to 9bit. In the temperature range of -40~125 ℃, the gain linear of analog front-end changes is only 4.5%. In the design of high precision temperature sensor, researchers fully considered the operational amplifier offset, BJT(Bipolar Junction Transistor) mismatch, current mirror mismatch error, BJT fabrication errors and quantization circuit offset, they took the technology of discrete time mode, the average time control method, BJT gain nonlinear calibration and device mismatch correction to complete the mission. Finally, in the temperature range of 20 ~ 125℃, the inaccuracy of temperature sensor is controlled within ± 0.1 ℃.
In recent years, with the development of infrared sensing technology, the thermopile infrared detector manufactured by MEMS (Micro-Electro-Mechanical Systems) technology gets much more attention because of its low power, light weight, compact volume, short warm-up time and low cost. Moreover the production process is compatible with standard CMOS(Complementary Metal Oxide Semiconductor) process and is easy to be integrated with peripheral signal processing circuit. So it has become hot research topic in the field of industry and science. The thermopile analog front-end and high precision temperature sensor chip developed in IMECAS is the first domestic high performance ASIC(Application Specific Integrated Circuit) chip for thermopile and has come up to advanced world standards, which make a good foundation for high performance infrared sensor chip R & D and industrialization in China.

Fig. 1 ENoB and SFDR(Spurious Free Dynamic Range) Result of Thermopile Analog Front-End （Image by IMECAS）

Fig.2 High Precision Temperature Sensor Chip(Image by IMECAS)

CONTACT:
Researcher HEI Yong
Institute of Microelectronics of Chinese Academy of Sciences
E-mail: heiyong@ime.ac.cn
Website of Dept.:
http://english.ime.cas.cn/Research/ResearchDivisions/LAB2/