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The integration of high-quality (Q)-factor 3-D filters with highly efficient antennas is addressed in this dissertation. Integration of filters and antennas into inseparable units eliminates the transitions between the otherwise separate structures resulting in more compact and efficient systems. The compact, highly efficient integrated 3-D filter/antenna systems, enabled by the techniques developed herein, allow for the realization of integrated RF front ends with significantly- reduced form factors. Integration of cavity filters with slot antennas in a single planar substrate is first demonstrated. Due to the high Q factor of cavity resonators, the efficiency of the integrated filter/antenna system is found to be the same as that of a reference filter with the same filtering characteristics. This means a near 100% efficient slot antenna is achieved within this integrated filter/antenna system. To further reduce the footprint of the integrated systems, vertically integrated filter/antenna systems are developed. We then demonstrate the integration of cavity filters with aperture antenna structures which enable larger bandwidths compared with slot antennas. The enhanced bandwidths are made possible through the excitation and radiation of surface waves. To obtain omnidirectional radiation patterns , we integrate cavity filters with monopole antennas. Finally, the integration of filters with patch antennas is addressed. Unlike the other filter/antenna integration examples presented, in which the antenna is utilized as an equivalent load, the patch antenna provides an additional pole in the filtering function. The presented techniques in this dissertation can be applied for filter/antenna integration in all microwave, and millimeter-wave frequency regions

Numerous techniques exist for measuring temperature using passive devices such as SAW filters. However, SAW filters have a significant limitation regarding high temperature environments exceeding 1000⁰C [1]. There are several applications for a high temperature sensor in this range, most notably heat flux or temperature in turbine engines. For these environments, an alternative to SAW filters is to use a passive resonator. The resonate frequency will vary depending on the environment temperature. Understanding how the frequency changes with temperature will allow us to determine the environmental temperature. In order for this approach to work, it is necessary to induce resonance in the device and measure the resonance frequency. However, the extreme high temperature makes wired connections impractical, therefore wireless interrogation is necessary. To be practical a system of wireless interrogation of up to 20cm is desired.

The resonance frequency of a silicon nitride (SiN) nano-electromechanical systems (MEMS/NEMS) can be measured precisely due to their large quality factor that is associated to low thermomechanical fluctuations. While these properties enable the fabrication of high performance sensors, their use will eventually raise questions regarding their long-term stability, notably for calibration purposes. The long-term frequency stability and aging of SiN are less studied than the short-term fluctuations such as thermomechanical noise. Long-term aging studies exist for quartz clocks as well as MEMS silicon clocks and accelerometers, but not for SiN resonators with high quality factors. Thus, in this work we conduct the aging study of SiN membranes fabricated by our lab, by constantly tracking changes of the resonance frequency of the device over a long period. The evolution of the frequency drift is tracked, by optical interrogation, continuously for 135 days with a digital phase locked loop (PLL). Our device is placed in a cell under high vacuum to suppress air damping on our resonating membrane. Furthermore, due to its high sensitivity to temperature changes, our silicon nitride resonator and vacuum chamber are placed in an air bath providing a stable temperature (within 0.5 K over 135 days in the present case). To compensate further the frequency drifts induced by temperature changes, a multimeter measures the resistance of a calibrated thermistor placed inside the vacuum environment. The measured frequency drift for the aging periods of 135 days was of 300 parts per million (ppm) and was consistent with previously reported double logarithmic models for quartz oscillators. The initial stage of negative frequency drift, in our aging data, is consistent with the behaviour expected from the desorption of water due to the transition from ambient air environment to high vacuum. We review models explaining how water adsorption/desorption impacts our membrane's frequency by (1) inducing chemical reaction stresses (most important effect), (2) through the contribution of the water surface tension stress (non-negligible effect), and (3) through mass loading from water molecules (weakest effect). After this initial negative trend, the membrane frequency drift inverts and increases almost linearly, in a fashion consistent with loss of mass from desorption of other chemical species. To identify these chemical species, X-ray photoelectron spectroscopy measurements were conducted on a reference membrane stored in an ambient setting and on our membrane placed under vacuum during our aging studies. The aged membrane, compared to its reference counterpart, contained substantially less alkaline ion contaminants (i.e., sodium, calcium and potassium), most likely due to desorption of these species during the aging measurement, and to the increase in adsorption occurring on the reference membrane concurrently. We therefore hypothesize that trapped negative charges, which is a typical phenomenon within dielectric materials such as SiN, might progressively attract positive ion contaminants over time when the device is exposed to ambient air.

The electromagnetic spectrum is becoming increasingly congested due to the rapid development of wireless and mobile communication in recent decades. New, compact and efficient passband filters with multi-functions and good performance are highly demanded in current and future wireless systems. This has also driven considerable technological advances in reconfigurable/tunable filter and filtering antenna designs. In light of this scenario, the objectives of this thesis are to design, fabricate and measure efficient, compact, multi-standard, and reconfigurable/tunable microstrip resonator filters and study the integration of the resonators with patch antennas. As a passive design, a compact dual-band filter is implemented to cover 2.5 to 2.6 GHz and 3.4 to 3.7 GHz for 4G and 5G, respectively. Another design is also presented with the advantages of a wide passband of more than 1 GHz. Conversely, new and compact reconfigurable filters are designed using varactor and PIN diodes for 4G and 5G. The proposed filters are tunable in the range from 2.5 to 3.8 GHz. The bandwidth is adjustable between 40 and 140 MHz with return losses between 17 to 30 dB and insertion loss of around 1 dB. Also, the thesis investigates the design of cascaded and differentially-fed filtering antenna structures. The cascaded designs operate at 2.4 and 6.5 GHz and have a relatively wide-band bandwidth of more than 1.2 GHz and a fractional bandwidth of more than 40%. For the differentially-fed structures, good performance is achieved at the 3.5 GHz with a high realized gain of more than 7.5 dBi is observed. / European Union Horizon 2020 Research and Innovation Programme (Marie Skłodowska-Curie Actions) under grant agreement H2020-MSCA-ITN-2016 SECRET-722424.

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<p>The continuous reduction of feature size in silicon-based electronic integrated circuits (ICs) is accompanied by devastating propagation delay time and power consumption that have become known as the “Interconnect Bottleneck”. Optical interconnection is a proposed solution that is poised to revolutionize the data transmission both within and between ICs. By forming the optical transmission and functional elements from silicon, they can be monolithically incorporated with standard ICs using the established CMOS (Complementary Metal Oxide Semiconductor) infrastructure with minimal incremental cost. A key required functional element is the photodetector, which provides optical-toelectrical conversion of signals. In this thesis, a method of achieving such conversion is explored, which uses the optical absorption at 1550 nm wavelengths provided by lattice defects. The physics governing defect-enhanced silicon waveguide photodiode operation is described, and a device model is used to verify the posited detection process and propose design improvements. The model was used to design a novel photodetector structure using a waveguide formed by the LOCOS (LOCal Oxidation of Silicon) process with a poly-silicon self-aligned contact. The fabricated device exhibited a responsivity of 47 mA/W, providing an improvement over previous devices of similar dimensions, although were ultimately limited by the quality of the poly-silicon/silicon interface. A sub-micron waveguide photodiode fabrication process using electron-beam lithography was developed, which produced photodiodes with responsivities of 490 mA/W. This process was used to integrate photodiodes onto micro-ring resonators, which exhibit resonant enhanced photocurrent. The physics of this enhancement were explored, and found to produce a 50 μm long resonant photodiode of responsivity equal to that of a 3 mm long non-resonant photodiode. Lastly, the integration of such sub-micron photodiodes as functioning power monitors throughout photonic circuits was demonstrated as a means to characterize and tune micro-rings during operation.</p> / Doctor of Philosophy (PhD)