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Hussein Hussein’s PhD Dissertation Defense
April 13, 2023 @ 4:00 pm - 5:00 pm
“Parametric Circuits for Enhanced Sensing and RF Signal Processing”
Prof. Cristian Cassella (Advisor)
Prof. Marvin Onabajo
Prof. Matteo Rinaldi
Prof. Andrea Alù
Massive deployments of wireless sensor nodes (WSNs) that continuously detect physical, biological or chemical parameters are needed to truly benefit from the unprecedented possibilities opened by the Internet‑of‑Things (IoT). Just recently, new sensors with higher sensitivities have been demonstrated by leveraging advanced on‑chip designs and microfabrication processes. Yet, WSNs using such sensors require energy to transmit the sensed information. Consequently, they either contain batteries that need to be periodically replaced or energy harvesting circuits whose low efficiencies prevent a frequent and continuous sensing, even impacting the maximum range of communication. Here, we discuss a new battery-less and harvester-free remote sensing tag, namely the subharmonic tag (SubHT), leveraging unique nonlinear characteristics to fundamentally break any previous paradigms for passive WSNs. SubHT can sense and transmit information without requiring supplied or harvested DC power. Also, it transmits the sensed information at a difference frequency from the one of its interrogation signal, rendering its reader immune from multi-path, from clutter and from its own self‑interference. Also, even though SubHT may not require any advanced and expensive manufacturing, its unique nonlinear response enables extraordinary high sensitivities and dynamic ranges that can even surpass those achieved by the most advanced on-chip sensors. More interestingly, SubHT can be even configured to operate in a “threshold sensing” mode, making it able to respond to any interrogation signal only when the sensed parameter has exceeded a remotely reprogrammable threshold, as well as to memorize any violation in a sensed parameter without requiring any memory components. In this talk, the first SubHT prototypes for temperature sensing will be showcased. Even more, we will show how including high quality factor (Q) resonators in a SubHT’s network allows to implement even more functionalities, such as the long-range identification or tracking of any items or localization and navigation in a GPS denied environment. Yet, the dynamics exploited by SubHT can also be leveraged to address various needs along radio-frequency (RF) chains. In this regard, we show how the SubHT’s nonlinear dynamics can be leveraged to build components, such as parametric filters, frequency selective limiters and signal to noise enhancers, that improve the stability of RF frequency synthesizers and instinctually suppress co-site or self-interferes, paving an unprecedented path towards integrated radios with improved performance and longer battery-life time.