基于LTCC技术的多级微波滤波器的研究与设计

发布时间：2018-08-10 22:16

【摘要】：随着通信领域的快速发展,尤其是无线通信和互联网通信的兴起,信号的频率资源变得日益紧张,同时随着移动互联终端的广泛普及,向微波射频电路和集成电路等电子器件提出了小型化、高性能、高可靠性等要求。而滤波器作为通信系统中控制信号传输的关键器件,对整个通信系统起着决定性的作用。因此滤波器的高性能和小型化的研究已经成为当下备受关注的热点问题。多级滤波器通过增加谐振级个数,有效地加强了各级之间的耦合效应以增强带外衰减、降低过渡带矩形系数,提高边带陡峭,从而优化滤波器的性能。同时结合具有低成本、微型化、耐高温等优点的低温共烧陶瓷(LTCC:Low Temperature Co-fired Ceramic)技术,实现小型化的生产目标。本文围绕基于LTCC技术的多级微波滤波器的研究与设计这个课题,探究微型化设计方案,针对不同频段、不同结构、不同应用领域的滤波器的特点,完成了以下工作:(1)完成了一款六级低通滤波器的研究与设计,其截止频率3.2GHz,采用集总结构实现。充分利用了 LTCC内埋技术,在原型电路基础上加入传输零点以加快带外衰减,同时在级联理论基础上对三级结构进行级联优化,获得了较好的测试结果。(2)完成了两款基于带状线结构的多级带通滤波器的设计与相关研究,分别为中心频率3.45GHz的八级带通滤波器及中心频率2.8GHz的十二级带通滤波器。首先调节单级谐振单元确定工作频率,再根据谐振级之间的耦合效应不断增加级数,同时引入Z字型结构引入传输零点,设计过程有效验证了多级结构对于滤波器带外性能的优化,以及随着级数增加而带来的影响。(3)设计并分析了一款多模形式的多级带通滤波器,中心频率7GHz,相对带宽85.7%。根据多模原理选择合适的谐振结构,并且利用加载电容增强级间耦合,同时加入了缺陷地结构改善高频寄生通带,并且研究了设计中的相关影响因素。本文研究设计的四款滤波器充分利用了 LTCC技术的特点,综合考虑性能和尺寸的设计要求,最终获得了优异的滤波性能,集成度高。其中两款已完成实际生产与测试,性能与理论设计契合度较高,已经进行批量生产,成品率80%以上,应用广泛。
[Abstract]:With the rapid development of communication field, especially the rise of wireless communication and Internet communication, the frequency resources of signals become increasingly tight, and with the widespread popularity of mobile interconnected terminals, Miniaturization, high performance and high reliability are required for microwave RF circuits and integrated circuits. As the key device to control signal transmission in communication system, filter plays a decisive role in the whole communication system. Therefore, the research of high performance and miniaturization of filters has become a hot issue. By increasing the number of resonant stages, the multistage filter effectively strengthens the coupling effect between different levels to enhance the out-of-band attenuation, reduce the rectangular coefficient of the transition band, and improve the steepness of the sideband, so as to optimize the performance of the filter. At the same time, the low temperature co-fired ceramics (LTCC:Low Temperature Co-fired Ceramic) technology which has the advantages of low cost, miniaturization and high temperature resistance is combined to realize the production goal of miniaturization. This paper focuses on the research and design of multistage microwave filters based on LTCC technology, and explores the miniaturization design scheme, aiming at the characteristics of filters with different frequency bands, different structures and different application fields. The main works are as follows: (1) A six-stage low-pass filter is studied and designed. The cutoff frequency is 3.2GHz, and the lumped structure is adopted. Taking full advantage of the LTCC embedded technology, the transmission zero is added to the prototype circuit to accelerate the out-of-band attenuation, and the cascade optimization of the three-level structure is carried out on the basis of the cascade theory. Good results are obtained. (2) two multistage bandpass filters based on banded line structure are designed and studied. They are 8-stage bandpass filters with center frequency 3.45GHz and 12-stage bandpass filters with central frequency 2.8GHz. First, the single-stage resonant unit is adjusted to determine the working frequency, then the series is increased according to the coupling effect between the resonant stages, and the transmission zeros are introduced into the Z-shaped structure at the same time. The design process effectively verifies the multi-level structure's optimization of the out-of-band performance of the filter and its influence with the increase of the series. (3) A multi-mode multistage band-pass filter with a center frequency of 7 GHz and a relative bandwidth of 85.7 GHz is designed and analyzed. According to the multi-mode principle, the appropriate resonant structure is selected, and the interstage coupling is enhanced by using the loaded capacitance, and the high frequency parasitic passband is improved by adding the defective ground structure, and the relevant influencing factors in the design are studied. The four filters studied and designed in this paper make full use of the characteristics of LTCC technology and take into account the design requirements of performance and size. Finally, excellent filtering performance and high integration are obtained. Two of them have been produced and tested in practice, with high agreement between performance and theoretical design. They have been produced in batches with a yield of more than 80% and have been widely used.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN713

【参考文献】