Biography
Enrollment Date: 2008
Graduation Date：2011
Degree：M.S.
Defense Date：2011.05.24
Advisors：Hanjun Jiang
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：A Wireless SoC for Alimentary Canal pH Value Continuous Monitoring
Abstract:
Gastroesophageal reflux disease is a regular clinical disease which has a relative high morbidity rate. The most effective instrument is the gastroscope. The advantage of the gastroscope is that it can diagnose visually, while it has several disadvantages. Gastroscope is unable to diagnose the GERD at its very early stage because there is no organic damage inside the alimentary canal and it can`t successively detect because it brings a lot of discomfortbelness to the patient. There is a new type of device which integrates pH sensor, sensor interface, digital controller, wireless transceiver and battery into one small capsule. This capsule is attached onto the surface of the alimentary canal and it is able to monitor the variation of the pH value of the alimentary canal. The variation of the pH value is a critical evidence of the GERD. The capsule existed today is has several disadvantages of size, accuracy, battery life because of the circuit design. This thesis proposed a SoC for such a capsule explained above. This SoC integrates pH sensor interface, power management, RF transceiver and digital control unit and realizes all the functions mentioned in the previous paragraph. The SoC is fabricated using 0.18µm standard CMOS process and occupies an area of 2.0mmX1.6mm. The digital controller has almost 60000 equivalent logic gates. The test results of the SoC proves that the system work correctly. It can detect the signals of the pH sensor interface, quantize, buffer, package and transmit to the receiver. The receiver can demodulated the pH value data correctly. The accuracy of the SoC is about 0.3pH which is even better than the foreign mature products. All the results meet the requirements. The biggest power consumption comes from the RF transceiver. The power supply of the RF transceiver is 2.5 volt while the current is 2.5mA. The power supply of the pH sensor interface is 3 volt while its current is 200uA. The power consumption of the digital controller and power management is relatively small compared with RF transceiver and neglectable. The SoC won`t work successively, so the real power consumption of the SoC is much smaller than the sum，approximately1mW.