A study of RF front-end circuit module for ultra wideband system

• Main Authors: Chin-feng Chou, 周金鋒
• Other Authors: Tzyh-Ghuang Ma
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/3hx432

碩士 === 國立臺灣科技大學 === 電機工程系 === 95 === This thesis investigates the RF front-end circuit module for the ultra wideband system (UWB). In the study we use the circuit simulation tool Agilent ADS and the electromagnetic simulation software Ansoft HFSS to perform the circuit design, analysis, and verification. Firstly, we deal with the RF front-end circuits in the transmitter. By building up the equivalent circuit model of the step recovery diode (SRD), the performance pf the pulse generator can be substantially enhanced. Two pulse generators, the Gaussian pulse generator and the monocycle generator, are designed, fabricated, and experimentally demonstrated. In addition, to alleviate the potential interference between the UWB systems and the WLAN radios, in Chapter 3 we introduce a three-order band-rejection filter to the pulse shaper at the frequency range of 5 to 6 GHz by utilizing the defected ground structure (DGS). In the study of RF front-end circuits in the receiver, we first reproduce a microwave sampler in the literature on a low-cost FR4 substrate. The analysis including dynamic range and conversion linearity are discussed in terms of both simulated and measured results. To miniaturize the circuit dimension of the microwave sampler, in Chapter 5 we proposed a new magic-T circuit design. This novel magic-T is realized by a three-layered fabrication process with the help of electrically coupled microstrip lines through slotted aperture on the common ground plane. The new microwave sampler is composed of this miniaturized magic-T and the sampling bridge with two Schottky diodes. The experimental results demonstrate significant improvement on both dynamic range and conversion linearity, and the percentage of size reduction is as high as 75%. This thesis provides some valuable information for practical UWB applications and also establishes the fundamental building blocks for future study on pulse radios.