Biography
Enrollment Date: 2008
Graduation Date：2011
Degree：M.S.
Defense Date：2011.05.24
Advisors：Woogeun Rhee
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Research on FM-UWB transmitter for wireless
Abstract:
The FM-UWB technique can be seen as an analog implementation of a spread-spectrum system with a spreading gain equal to the modulation index which generates a low complexity and constant-envelope UWB signal, featuring a very steep spectral roll off. This dissertation will focus on the research of the sub-carrier modulation and RF modulation for FM-UWB and the detailed circuit design for the critical blocks in the transmitter. Fractional-N PLL is used for sub-carrier modulation in this dissertation. With the increasing of data rate, the reference frequency of PLL will also increase at the situation of keeping over sampling rate unchanged, meanwhile, if the DIV rate is added, the frequency of sub-carrier is increased, which leads the power spectrum density cannot meet the UWB spectral mask provided by FCC. The dissertation gives FM-UWB transmitter modeling design with 500kb/s firstly, it simulates in the process of TSMC 65nm CMOS, the Ring-VCO with 8-phase output not only generate sub-carrier signal, but also let the system use a low dividing ratio of 1/1/125, then the output frequency of sub-carrier is reduced. In the FLL, one high gain Ring-VCO is used, whose central frequency is 8GHz, to realize RF modulation. It can generate a high UWB bandwidth, and then βRF is increased, the PSD of UWB signal can meet the mask of FCC, which can be proved by simulation result. The dissertation presents sub-carrier modulation for FM-UWB transmitter which is taped out in UMC 0.18um CMOS, the chip integrated accumulator, FSK Modulator, PFDCP, SPI interface, Relax-VCO and so on. The test result shows that a good sub-carrier signal, and analyze the undesirable UWB spectrum.