Development of circuits and systems for optical data links in biomedical applications

In biomedical applications, optical communication links guarantee high data rates, low power consumptions and high electromagnetic compatibility. From these considerations, in this Thesis novel circuits and systems for optical data links in biotelemetry applications have been developed. More in detail, a complete biotelemetry system has been designed and implemented, both with discrete components and as full-custom integrated circuit. It includes digital architectures for the data coding/decoding, employing an UWB-based modulation technique, and analogue circuits to drive lasers and for the signal conditioning of photodiodes. The system has been firstly implemented and tested by using commercial devices so achieving data rates up to 300 Mbps with an energy efficiency of 37 pJ/bit and a maximum BER of 10−10. Subsequently, the developed solution has been suitably designed, at transistor level, for its microelectronic integration in AMS 0.35 μm standard CMOS technology and, after its fabrication, has been fully characterized with data rates up to 250 Mbps so obtaining an energy efficiency of 160 pJ/bit with a maximum BER of 10−10. Moreover, possible applications of the system are also reported, such as a neural recording system (work in collaboration with the Centre for Bio-Inspired Technology, Imperial College London, UK), a tactile sensory feedback system (work in collaboration with the COSMIC Lab, DITEN, University of Genova, Italy) and an event-driven serial communication on optical fiber for robotic applications (work in collaboration with iCub Facility, Istituto Italiano di Tecnologia - IIT, Genova, Italy). Furthermore, the acquired skills have been employed to design optoelectronic circuits and systems to be applied to optical transcutaneous oxygen sensing solutions that result to be particularly important for the fight against the COVID-19 pandemic. More in detail, different full-custom integrated photodiodes and analogue front-end circuits for their interfacing, as well as an optical wireless power transfer system, have been also developed (work in collaboration with the Worcester Polytechnic Institute, Worcester, USA). Finally, further related works, always concerning biomedical applications, are reported as appendices.