Wide tunable CMOS active inductor

Abstract

A tunable CMOS active inductor is presented. The circuit uses a cross-coupled pair of transistors providing positive feedback for enhanced quality factor. The circuit is biased with a controllable current source varying the feedback and tuning the inductor. The proposed inductor is designed and simulated in a 90 nm digital CMOS process. It shows a wide-frequency range inductive impedance and a very high resonance frequency. By cascading two inductors, a wideband filter/amplifier is designed to characterise the inductor performance.