Biography
Enrollment Date: 2011
Graduation Date：2014
Degree：M.S.
Defense Date：2014.05.14
Advisors：Woogeun Rhee
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Research on Impulse Radio Ulta-Wide Band Radar for Vital Signal Detection
Abstract:
Nowadays, wireless communication has been one of most “hot” research field in the world, and it also places significant influences on human’s life. Meanwhile, along with the development of economics, people tend to pay more attention on medical service. There is a huge gap between the growing demand for better medical service and the slowly increasing amount of doctors and nurses. Therefore, mobile medical service will be huge market in the future.
Among the physical implementations in the protocol of IEEE 802.15.6, UWB (Ultra-Wide Band) is a most competitive choice for simple system architectures, low power consumption and high resolution in time domain against conventional narrowband communication system. Compared to FW-CW-UWB, IR-UWB has even smaller power consumption and higher time-resolution. Therefore, IR-UWB is more appropriate to WBAN application.
In the conventional architectures, the transmitter couldn’t utilize the frequency band effectively, and also increase the design burden in receiver. Using the concept of frequency-hopping will relieve the design burden and power consumption in receiver and boost the efficiency of frequency band. At the same time, utilizing multi-bit ΔΣ TDC (Time-to-Digital Converter), we can decrease the distortion in the output of Radar due to “cross boundary” issue, which also boost the resolution of TDC. This thesis mainly contributions is two critical building blocks-–closed-loop transmitter and multi-stage multi-bit ΔΣTDC with high resolution for this Radar system.
To calibrate the carrier frequency with receiver, this transmitter utilizes a PLL (Phase Lock Loop) to generate carrier frequency with low phase noise. This PLL can lock up quickly in several frequencies. Also the pulse shaping technique is used to generates pulse approximately to second-order pulse to gain a low out-band Emission and high frequency-utilizing ratio. We also use BPSK to do the “scrambling”, which make the spectrum more smooth. The top-level simulation is given in this thesis.
For the second-order multi-bit TDC, this thesis use “single loop” architecture to avoid the negative influence from non-ideal element in the circuits, and the parameters are also optimized by behavior-level simulations. The TDC also make use of “capacitor splitting”technique to reduce the non-linearty from D/A converters. The phase rotator is given to enlarge the effective range for TDC. This thesis also analyzes the negative influence non-ideal placed on the circuits. The thesis presents the top-level simulation results and the performance comparisions.
All the building blocks presents in this thesis has been taped out under the process in TSMC 65nm Standard CMOS.