Biography
Enrollment Date: 2009
Graduation Date：2012
Degree：M.S.
Defense Date：2012.05.24
Advisors：Baoyong Chi
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Research on the ALL Digital Polar Transmitter
Abstract:
With the increasing demand of wireless communication, in order to be compatible with various wireless communications standards so that they can be portable in the same workbench. Software define radio (SDR) concept is proposed. At the same time, CMOS technology development makes the chip highly integrated, and the digital circuit is more and more powerful, but the development of the process do not bring great advantages to the traditional radio frequency circuit In fact in deep sub-micron, digital circuit’s time precision is better than analog circuit voltage accuracy.
This thesis discusses the digital RF techniques as well at its actual implementation. We can combine the power of baseband digital signal processing technology with radio frequency communications to put the digital signal to the RF front-end. Based on the requirements of the current 3G mode--WCDMA standard, we discuss the system design issues as well as its implementation
In the system architecture , the polar digital transmitter is utilized, instead of the traditional cartesian transmitter based on the IQ modulation. Its specific performance is present with this mode, in which the modulated signals from the baseband pass through digital filters for pulse shaping, and then go through the coordinates rotation digital calculation method (CORDIC) to separate the amplitude and phase information. And then the isolated of the amplitude and phase information go through different signal processing path: the phase signal is differentiated to become frequently signal, which is as a frequency command word directly into the all digital phase locked loop(ADPLL)to realize the frequency modulation. In the amplitude signals path, the amplitude signal is sent to the digital predistortion circuits, coding circuits, delay matching circuits in turn and eventually comes cross with the frequency modulated signal from all digital phase locked loop (ADPLL) in digital power amplifier ,which has functions of the frequency mixing, digital analog convertion, and band-pass filter.
In the end we present the system simulation results and also discuss the implementation of some blocks.