EDITOR'S NOTE Leo Belostotski Welcome to the Summer 2021 Issue of IEEE Solid-State Circuits Magazine! T This third issue of the 13th year of IEEE Solid-State Circuits Magazine recognizes two of many excellent tutorials presented this year at the International Solid-State Circuits Conference (ISSCC). A tutorial by Sudip Shekhar introduces silicon photonics circuits and discusses their use in high-speed transceivers. In the second tutorial, David Wentzloff, Abdullah Alghaihab, Jaeho Im, Omar Abdelatty, and Trevor Odelberg examine performance trends and architectures for ultralow-power receivers. In addition to the ISSCC tutorials, a fun article of interest to the magazine's readers that is featured in this issue is " Fifty Nifty Variations of Two-Transistor Circuits " by Harald Pretl and Matthias Eberlein. Digital Object Identifier 10.1109/MSSC.2021.3088962 Date of current version: 25 August 2021 This issue also includes the alwayspopular tutorial columns by Ali Sheikholeslami and Behzad Razavi as well as the second article in a new tutorial column by Chris Mangelsdorf. Behzad's " The Analog Mind " column introduces a step-by-step design of low-voltage bandgap-reference cirIn addition to the ISSCC tutorials, a zine's readers that is featured in this cuits. Ali's " Circuit Intuitions " column tackles the use of ac coupling in wireline communication systems. And Chris's " Shop Talk: What You Didn't Learn In School " column provides a case for zero-gain amplifiers. The goal of this magazine conissue is " Fifty Nifty Variations of Two-Transistor Circuits " by Harald Pretl and Matthias Eberlein. a series of self-contained resources to keep SSCS members up to date with changes in technology while, at the same time, providing fun article of interest to the magareviews of circuitdesign concepts. This includes contributions from experts describing the current state of affairs and the evolution of a particular IC technology. We will also continue to feature articles focused on the contributions of luminaries and on solid-state circuit techtinues to be to provide Society news and information as well as niques and directions. We hope you enjoy reading IEEE Solid-State Circuits Magazine. Please send comments to lbelosto@ieee.org. 4 SUMMER 2021 IEEE SOLID-STATE CIRCUITS MAGAZINE