Biography
Enrollment Date: 2009
Graduation Date：2012
Degree：M.S.
Defense Date：2012.05.25
Advisors：Liji Wu
Department： Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Design and Implementation of Low Power 433MHz Transmitter for Battery-Less Tire Pressure Monitoring System
Abstract:
Recently, Tire Pressure Monitoring System （TPMS）has been rapidly developed in the country. Many intermediate and high-end cars have already installed TPMS, which has been becoming an indispensable active safety device for safe driving. The battery-less TPMS has many advanteges over the TPMS with battery. So it draws more and more attention from academia and industries. It can be predicted that the battery-less TPMS will have a very broad market prospects. How to design low power SoC is the most concern for designer for designer of the passive TPMS. Because the RF data transmitter consumes the most of the power consumption of passive TPMS, to design a low power transmitter will be very important.
Our team proposes a battery-less TPMS implementation based on electromagnetic coupling. The thesis is to design a fully integrated low-power transmitter which applies to the passive TPMS. The passive TPMS based on electromagnetic coupling has many restricts and performance requirements for the transmitter, which constitutes the research basis and background. The work consists of several parts, including obtaining the detailed technical specifications by a careful derivation and proposing the optimal structure of the low-power transmitter according to the design specifications. The most important work is to find compromise among low-power, low cost and fully integrated to meet the design specification.
The thesis proposes an OOK low-power 433MHz transmitter, which is mainly made up of an integral PLL frequency synthesizer and a RF power amplifier. The integral PLL frequency synthesizer includes PFD, CP, loop filter, VCO and frequency divider. The whole procedure of chip design contains circuit modules desgign, simulation, layout, post-simulation, testing and analysis. The transmitter has been taped out twice using UMC 0.18um MM/RF process. All modules have been integrated in one chip except for several capactors and inductors; the whole die area is about 1mm x 1mm. The test results of the first version transmitter shows that the maximum output power of the transmitter is up to 3 dBm. At this moment, the power amplifier efficiency is about 40% and the current consumption of the power amplifier is only 3mA. The phase noise of VCO is about -112dBc/Hz@300KHz. These results also show that most of the modules designed meet the expected requirements. The second version of transmitter has been taped out based on optimizing and improving for the first design, the test results are similar with the first version results. Locked time of PLL is about 180us and the total consumption current is below 19mA. The measurement results show that the transmitter can meet the requirement of design.