ISCAS 2021 invites technical contributions across the CAS spectrum from theory, analysis, and design to practical implementation of circuits and systems. The IEEE Circuits and Systems Society maintains standing Technical Committees that foster technical activities in these diverse areas. Representatives from the technical committees are responsible for ensuring qualified reviews of all papers submitted to ISCAS. The review process is topically organized into Tracks associated with one or more technical committees, which are divided into more specific subtracks listed below. At the time of paper submission, authors select the most relevant subtrack in order to facilitate the selection of reviewers with suitable expertise. In the case of interdisciplinary contributions, authors are encouraged to select a secondary subtrack. Circuits and systems contributions are welcome in all subtracks (as are hardware, embedded systems, VLSI, and integrated circuits contributions).