Author

Jinqun Ge

Date of Award

Spring 2023

Document Type

Open Access Dissertation

Department

Electrical Engineering

First Advisor

Guoan Wang

Abstract

Over the past several decades, wireless communications have been tremendously developed with multiple frequency bands, standards, and functions to provide more convenient communication services. Nowadays, commercial wireless devices, especially customer premises equipment, are required for smaller size, higher integration, and higher data rates to meet the ever-increasing demands of communications. The transceiver front ends inside these devices need to provide high-speed and high-quality communication services without a substantial increase in cost and size. Hence, the primary objective of this research is to develop a few miniaturized, multifunctional, and reconfigurable RF technologies and to provide several signal integrity and heat dissipation improvement solutions for the highly integrated system with high data transfer rates.

A promising way to shrink the communication systems is to replace the repetitive and cumbersome RF passive devices with a few multiband and multifunctional RF components. Hence, a basic filtering structure is developed in this dissertation to provide a dual-band filtering response with high selectivity. Multiple transmission poles are generated by utilizing half-wavelength and open stub loaded resonators. In addition, a novel coupling scheme is applied to the design to generate multiple transmission zeros, leading to highly selective passband and good out-of-band rejection. This filtering structure is applied to design a switch-controlled reconfigurable dual-band bandpass filter and a dual-functional filtering balun. The excellent performances of the implemented filter and filtering balun show the great superiority and design efficacy of the proposed filtering structure.

Besides designing multifunctional or reconfigurable RF components in specific configurations, this dissertation investigates a more flexible solution to facilitate the reconfigurability and miniaturization of the integrated systems. Designing tunable and miniaturized RF components on engineered substrate enabled with ferromagnetic thin films is fully studied in the dissertation. By selectively patterning the ferromagnetic thin films, the engineered substrate provides increased and tunable effective permeability with limited losses. In order to achieve higher permeability, more or thicker ferromagnetic thin film layers are required. The performance of the RF components is dependent on the properties of the engineered substrate. It is critical to develop an accurate model which quickly optimizes and determines the configuration of the ferromagnetic thin film patterns in the engineered substrate for a desired permeability. In this dissertation, a multilayer substrate model is created by thoroughly exploring the impact of different factors on the performance of the engineered substrate, such as pattern dimensions, the number of film layers, film thickness, filling density, etc. To demonstrate the design efficacy of the developed model, a miniaturized and tunable frequency selective surface (FSS) and a performance-enhanced antenna are implemented on the optimized engineered substrate.

With the previous designs and techniques, a highly integrated system with multiple frequency bands and multiple functions is achieved. However, a highly integrated system suffers the signal integrity issue due to the far-end crosstalk in high-density traces, especially as the data transfer rates get higher and higher. Adding tabs between the coupled lines is an existing good way to reduce crosstalk. In this dissertation, thin film techniques are applied to further reduce the far-end crosstalk and improve the signal integrity of the highly integrated system. The far-end crosstalk of coupled transmission lines and the tabbed routing structure is thoroughly analyzed, and closed-form formulas are derived to characterize and optimize the performance. Based on the theoretical analysis, practical solutions are developed to further reduce the crosstalk between interconnects, including the application of ferromagnetic thin films and ferroelectric thin films and new interconnect structure with non-uniform signal line tab thickness.

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