Application of dielectric resonators to millimeter-wave on-chip filters and interconnects

越来越多的通信和传感应用使用频谱中的毫米波频段的频率。这一趋势推动了对无源元件创新概念的需求和发展，例如新的单片集成电路互连和低损耗片上带通滤波器。毫米波集成电路通常通过倒装芯片或线键技术安装在电路板上。然后存在许多解决方案将各种波导结构连接到电路板上。通过适当改进片上天线，提出了芯片与矩形波导或介质波导直接连接的简单解决方案。在申请人的遗留项目中，通过球形介电谐振器实现了片上微带线与矩形波导的耦合。实验表明，该概念在64 GHz时的传输损耗为2.6 dB，在损耗方面优于其他解决方案，同时在芯片面积消耗、组装复杂性和可测试性方面也具有优势。平面无源毫米波带通滤波器集成在片上时，通常嵌入在芯片顶层，但仍然存在明显的插入损耗和低选择性。另外，低损耗（高q因子）谐振器对振荡器特别重要，片上介电谐振器振荡器的频率高达60 GHz。这些振荡器使用圆柱介质谐振器，其中精确的放置可能是关键的，芯片面积消耗将是一个问题。在申请人的遗留项目中，对低损耗（高q）片上球形介电谐振器进行了一些研究。这些谐振器在特定高阶谐振模式下的辐射确实可以非常小，因此这些谐振器的卸载Q可以非常高，从而为实现高选择性片上谐振器和滤波器提供了可能。对氧化铝陶瓷制成的片上球形介电谐振器的测量表明，在64 GHz和103 GHz时，卸载Q值分别为1400和2200。本续计画旨在扩展使用片上球形介电谐振器的基本思想，以实现工作在100 GHz左右的片上多谐振器带通滤波器。由于先前设计的测试晶圆存在一些制造问题，该项目的延续也将提供机会改进制造技术，并在新的测试晶圆上重复和改进先前设计的一些耦合结构。

A growing number of applications in communications and sensing use frequencies in the millimeter-wave bands of the spectrum. This trend drives the need for and the development of innovative concepts for passive components such as new interconnects to monolithic integrated circuits and low-loss on-chip bandpass filters. Millimeter-wave integrated circuits are typically mounted on circuit board by flip-chip or wirebond technique. Many solutions then exist to connect all sorts of waveguiding structures to circuit boards. Solutions with less complexity were proposed with direct connections from chip to rectangular waveguide or to dielectric waveguide by means of suitably modified on-chip antennas. In the legacy project of the applicant, coupling from on-chip microstrip line to rectangular waveguide by means of a spherical dielectric resonator was realized. It was shown experimentally that this concept, with a measured transmission loss of 2.6 dB at 64 GHz, outperforms other solutions in terms of loss, while it also provides also provides advantages in chip area consumption, assembly complexity, and testability. Planar passive mm-wave bandpass filters, when integrated on-chip, are typically embedded in the top chip layers but still suffer from significant insertion loss and low selectivity. Alternatively, low-loss (high Q-factor) resonators are particularly important for oscillators, and on-chip dielectric resonator oscillators were proposed for frequencies up to 60 GHz. These oscillators use cylindrical dielectric resonators where accurate placement can be critical and chip-area consumption will be an issue. In the legacy project of the applicant, some investigations were done on low-loss (high-Q) on-chip spherical dielectric resonators. Radiation of these resonators in a specific higher-order resonance mode can indeed be very small and thus unloaded Q of these resonators can be very high, opening the possibility to realize highly selective on-chip resonators and filters. Measurements of on-chip spherical dielectric resonators made of alumina ceramic showed unloaded Q as large as 1400 at 64 GHz and 2200 at 103 GHz. The proposed continuation project aims to extend the basic idea of using on-chip spherical dielectric resonators for the realization of on-chip multi-resonator bandpass filters operating around 100 GHz. In consequence of some manufacturing issues with the previously designed test wafers, this project continuation will also give the opportunity to refine the manufacturing technology and to repeat and improve some of the previously designed coupling structures on a new test wafer.