Investigation Of 60 GHz High Gain And High Efficiency Microstrip Strcture On Chip Antenna In CMOS Technology

With the rapid development of wireless communication technology and the advancement of low-cost CMOS process technology, interests in silicon-based wireless system-on-chip(SOC) applications have become pervasive. As one of the most important part in the wireless communication system, investigations of on chip antenna in CMOS technology have become the focus, especially for 60 GHz. On chip antenna allows on-chip integration of digital baseband and complete RF front-ends, alleviating the need of impedance match from circuits to antenna. It has reduced antenna sizes to only a few millimeters, making it both possible and practical for compact on-chip implementation. However, there still exist a number of challenges for on-chip antennas: low antenna gains and radiation efficiency resulting from losses in low resistivity and high dielectric constant silicon substrates. In order to solve this problem, different kinds of methods have been approached. Some propose to use a high dielectric on the CMOS chip in order to enhance the radiation property or replace the low resistivity silicon with high resistivity. Since these special processes are not main stream and involving multiple post-processing steps, the complexity and relevant costs are higher. Others suggested improving the antenna performance in standard technologies by studying and designing new radiation mechanism such as using artificial magnetic conductors or implementing dielectric resonator. Considering and combining these brilliant approaches, this paper proposed a novel approach by adopting a ground plane in M1, designing a patch on top metal layer to radiate like microstrip antenna and implementing a dielectric resonator on top of patch antenna. Two different kinds of 60 GHz antennas including end-fire and side-fire application were designed, optimized, fabricated and measured. The main contents will include the followings:First of all, the background of the on chip antenna is briefly described and the development of on chip antenna is investigated. A general summary of various antenna types is presented to study the cause of radiation loss, explore the solutions to shield the microwave from penetrating into silicon substrate. Besides, the solutions of implementing the dielectric resonator are also discussed to make preparation for the high gain and radiation antenna design.In chapter 3, a ground plane on the bottom metal layer M1 has been approached to shield the wave from penetrating into the low-resistivity and high dielectric constant Si substrates to improve the antenna performance. The surface current of patch antenna and antenna parameters have been investigated to obtain an optimized antenna. A compact and high performance on chip antenna was designed with the help of High Frequency Structure Simulator(HFSS) from Ansoft Corporation based on Finite Element Method. After the antenna was taped out successfully, the antenna return loss was measured by adopting the Agilent vector network analyzer and the antenna gain was measured by building absolute gain test network. Also a comparison and discussion between measured and simulated results were done.In order to further improve the antenna gain, a square dielectric resonator was designed on top of patch antenna to form an intensified electromagnetic couple. This paper presents for the first time the design and performance of a novel integrated dielectric resonator antenna fabricated on the top of patch antenna. The electromagnetic couple between square dielectric resonator and patch antenna was analyzed and an initial structure and size of this intensified electromagnetic couple antenna can be obtained. A 60 GHz high gain and radiation efficiency side-fire on chip antenna was designed, optimized, fabricated. After the antenna was taped out successfully, the antenna was measured in the same way and a comparison and discussion between measured and simulated results were done.Considering the low gain and radiation efficiency of end-fire application of on chip antenna with traditional structure such as yagi, this paper presents a novel method with high end-fire gain by designing a square resonator on top of patch antenna to form a new kind of radiation pattern. A 60 GHz high gain and radiation efficiency end-fire on chip antenna was designed, optimized, fabricated and measured.Finally, the research results and practical significance were summarized and the future research directions were pointed out.