Recent Advances in Single-Ended Gyrator–C Active Inductor Designs (Innovations from 2008)

This chapter reviews the developments of single-ended gyrator-C active inductors from 2008 to the present. Based on the foundational work summarized in Ref. (Yuan, 2008), the discussion focuses on state-of-the-art CMOS implementations aimed at overcoming persistent challenges such as low quality factor, nonlinearity, high power consumption, and limited tunability. Each subsection highlights significant advancements, including improvements in transconductance and feedback architectures, as well as innovations in biasing, noise reduction, and layout optimization. Together, these developments demonstrate the ongoing evolution of active inductors toward becoming practical, high-performance alternatives to passive on-chip inductors, particularly for RF filters, oscillators, and impedance-matching networks in nanoscale CMOS technologies.