Direct Conversion Receivers in Wide-Band Systems.

摘要

The thesis is organized into six chapters. After the introduction, chapter 2 covers the basic background of the radio communications systems. The second part of the chapter focuses on the design parameters of the different analog blocks in a receiver at a fundamental level. Finally, the special requirements of wide-band CDMA receivers are analyzed. Chapter 3 introduces the different radio architectures and refers their properties to the performance of recent IC implementations. The architectures include superheterodyne, direct conversion, low-IF, wide-band IF, digital IF and direct digital receivers. Detailed discussion about direct conversion receivers is given in chapter 4. First, system level requirements are introduced. Then, radio design and different functional blocks are described. The special emphasis is in the RF front-end circuitry. Separate sections are reserved for active and subsampling mixers after the general considerations. At the end of the chapter the special issues of single-chip receivers are given followed by the comparison of reported direct conversion receivers and RF front-ends. The different IC implementations are described in chapter 5. A subsampling RF downconversion mixer is implemented with a digital GaAs MESFET process. A CMOS LNA and interface to a subsampling mixer concentrates to ac-coupling methods and efficient resonator structures for the load of the LNA. The two last sections contain the design and experimental results of a direct conversion receiver for WCDMA applications. The chipset and single-chip versions are presented separately. Both are implemented using the same BiCMOS technology. Chapter 6 summarizes the thesis.