Fei Yuan
Intelligent Instrumentation
Passive wireless microsystems harvest their power from radio-frequency waves emitted from base stations located in the proximity. They have found emerging applications in implantable electronics and wireless environmental monitoring. The efficiency of power harvest determines the maximum distance over which reliable links between base stations and microsystems can be established and the complexity subsequently the functionalities of the microsystems. Radio-frequency power harvesting efficiency is determined by the efficiency of the antenna of the microsystems, the accuracy of power matching between the antenna and the voltage multiplier for the maximum power transmission, and the power efficiency of the voltage multiplier that converts the received RF signal into a dc voltage from which microsystems are powered. In addition to power harvest, passive wireless microsystems often have the ability to perform sensing such as temperature sensing. The limited power resource of these systems imposes an ever-stringent constraint on the design of temperature sensors. Since the operation of passive wireless microsystems is controlled by their system clock, an ultra-low power on-chip clock that is locked to the incoming reference clock from the base station is needed. This project designs a passive wireless temperature sensor suitable.
Design a passive wireless temperature sensing system
1) ISM band (13.56 MHz) will be used for near-field power transmission and data communications between the base station and the temperature sensing system.
2) FSK for data modulation
3) Power harvest to convert the energy of incoming RF waves to 1.2 VDC to power the temperature sensing system.
4) Remote tuning of power harvest to maximize power harvest efficiency.
5) Remote tuning of systems clock to minimize the effect of process, voltage, and temperature (PVT) variations
7) IBM 130 nm 1.2V CMOS technology will be used for the design.
1) Study the fundamental of radio-frequency identification systems. Reference books will be suggested by the supervisor.
2) Develop the architecture of the system and the specifications of the building blocks of the system.
3) Carry out detailed circuit design of all building blocks and conduct extensive simulation to ensure that the performance of the building blocks meet the design specifications.
4) Carry out silicon implementation of the building blocks and conduct simulation to ensure that the performance of the building blocks meet the design specifications.
5) Test the designed temperature sensing system to ensure it satisfies all design specifications.
Define the overall specifications of the passive wireless temperature sensing system and the specifications of each building block. The group members of the project will work as a team to undertake this challenging project. A full corporation is needed to ensure the progress and completion of the project.
The student is responsible for the design of power harvester that include (i) impedance matching networks, (ii) matching transformer for amplitude boosting, (iii) rectifiers for ac-dc conversion, (iv) power-on logic, and (v) tuning of the power harvester to maximize its power efficiency. The matching transformer tanks should peak at the desired frequency to maximize the power efficiency of the power harvester. An automatic frequency adjustment system that will shift the resonance frequency to the desired frequency is needed.
The student is responsible for the design of a clock generator that supplies the system clock for the sensing system. An all-digital phase-locked loop that is locked to incoming signals from the base station will be used to generate the clock. The all-digital phase-locked loop includes a time-to-digital converter (TDC) phase detector, a FIR low-pass filter, and a digitally-controlled oscillator (DCO). In addition, the student is responsible for the design of a FSK modulator that maps measured temperature to a FSK signal.
The student is responsible for the design of an ultra-low power temperature sensor. A ring oscillator based temperature sensing approach is to be used. The developed temperature is to be calibrated.
ELE724
FY05: Passive Wireless Temperature Sensing System | Fei Yuan | Not yet submitted at No time