Biography
Enrollment Date: 2010
Graduation Date：2013
Degree：M.S
Defense Date：2013.05.28
Advisors：Liji Wu
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Integration Design for TPMS Mixed-Signal SoC and Implementation of Sensor Interface Circuit
Abstract:
With the progress of automotive industry, automotive electronics are used in many related fields, including safety, body control, power system and in-car entertainment. As an important part of automotive electronic system, the performance of automotive sensors makes great contribution to the function of system. Therefore, the design of sensor interface circuit, which stands the front-end position of automotive electronic system, should be a priority among system design.This paper looks over the difficulties in automotive chip design and the main feature of in-car sensors in a comprehensively inspect, and analyzes the mainstream approach to design of sensor interface circuits. On this basis, a dedicated structure of sensor interface circuit for MEMS pressure sensor in tire pressure monitoring system (TPMS), which plays an important role in automobile safety, is proposed in this paper. The interface circuit is composed of an instrument amplifier (IA) and a cyclic ADC with 8 bit resolution and 2KHz sample rate. The IA is fabricated in a 0.35um BCD&EE automotive process provided by ASMC. With a gain of 60, the test results show that the DC CMRR is 77.5dB and the input noise voltage is 96.8 nV@1KHz. The post-simulation result of ADC shows that the SFDR is 71.8dBc and SNDR is 49.4dB with 301.7Hz input frequency. The ENOB is calculated as 7.92 bit. The performance of the whole interface circuit meets the requirements of TPMS.This paper also completed the system design and behavioral level functional simulation of the in-tire module of TPMS, which is composed of MEMS pressure sensor interface circuit, power management circuit, 125KHz low frequency wake-up circuit, and a MCU with supporting EEPROM. All the modules have been designed with 0.35um ASMC BCD&EE automotive process and integrated as a mixed signal system on chip (SoC). This SoC has been taped out.