Biography
Enrollment Date: 2010
Graduation Date：2013
Degree：M.S.
Defense Date：2013.05.28
Advisors：Xiangyu Li Xiangmin Zhang
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Design and Implementation of a Power Management Circuit for Mixed-signal SoC in Tire Pressure Monitoring System
Abstract:
In this thesis, the research and design of the integrated power management for TPMS, based on automotive electronics CMOS process, has been introduced. The efforts include:
The application environment, the function and the operating principle of TPMS have been studied in detail. The conclusion has been gained that TPMS has the characteristics of wide operating temperature range, mixed-signal, low power, high stability and high reliability. Considering of the characteristics of TPMS, the object of the integrated low power, high stability and high reliability power management are presented, and the strategy of a power domain partition with analog and digital is introduced.
Considering of the characteristics of TPMS, the object and the strategy of the design, an integrated low power, high stability and high reliability power management structure is given, based on LDO, which includes LDO, band-gap reference, power monitoring circuit, over-current protection circuit and watchdog timer.
Then the research and design process of the sub-circuits is introduced.
Firstly, a low power, high stability band-gap reference has been studied and designed, which has the advantage of good temperature stability, good voltage stability, good load stability and the adjustable reference voltage. The reference voltage can be adjusted digitally to achieve high voltage accuracy. The minimum temperature drift of the band-gap reference is less than 1mV. And its power consumption is about 20μA.
Secondly, a low power, high stability LDO has been studied and designed, which has high output voltage accuracy. The disturbance of local power brought by the change of the load can be rejected well with 2.2μF off-chip capacitors. The PSRR of the LDO at 2MHz frequency is below -40dB, and its power consumption is less than 50μA. The LDO is suitable for both analog circuit and digital circuit.
Finally, the reliability scheme of the power management has been studied and designed. Considering of the battery failure, over-current and the process running fail, which usually happen in TPMS, the power monitoring circuit, over-current protection circuit and watchdog timer has been adopted, the implementation and simulation results of which are given. The simulation results have shown that three schemes can do trouble shooting well and improve the reliability of TPMS.
The proposed structure and circuits of integrated power management for TPMS have been implemented and verified by ASMC 0.35μm automotive electronics CMOS process for three times. The test work has been done for the first two times and the circuit is taping out for the third time. So there are post-layout simulation results of the third round design. The simulation and test results show that the power management of TPMS works well. The object is achieved. The requirements of TPMS for the power management are satisfied.