Spurious suppression techniques in integrated and embedded microwave components

Abstract

To increase bandwidth and mitigate interference in a crowded electromagnetic spectrum, future microwave systems will move to higher operating frequencies. Because lumped elements perform poorly at high frequencies, designers use distributed elements for most microwave circuits and systems. Traditional distributed elements such as waveguides and coaxial cables are bulky, heavy, and costly, making them unsuitable for applications that require reduced size, weight, power, and cost (SWaP-C). Consequently, these distributed technologies have been planarized and integrated into printed circuit boards (PCBs) and embedded in inner layers to save board space and costs. However, these new distributed technologies often create higher-order modes (HOMs), unintentional resonances, and periodic effects that degrade out-of-band performance. If these issues go unaddressed, microwave systems can experience data corruption, interference, or component damage. This thesis seeks to improve the performance of microwave components by exploring techniques to suppress spurious signals and responses. The proposed techniques suppress the periodicity of commensurate lines and dampen unintentional resonances. This work produces a design of an embedded, low SWaP-C, 3-GHz, low-pass filter with spurious response suppression of greater than 10 dB up to 14.5 GHz, compared to the original design with spurious responses starting at 8 GHz. The spurious suppression techniques demonstrated in this work have the potential to enhance the performance of many different integrated microwave components.