This special issue is a collection of selected papers presented at the IEEE International Symposium on Circuits and Systems (ISCAS) 2018 that was held in Florence, Italy, on 27-30 May 2018. As the flagship conference of the IEEE Circuits and Systems Society (CASS), ISCAS attracts researchers across all the main themes associated with the circuits and systems domain. ISCAS 2018 was attended by more than a thousand delegates presenting their papers on analog, mixed signal and digital circuits, communication systems, signal processing, power circuits and systems, and many other relevant and timely topics. [ABSTRACT FROM AUTHOR]