Integrated Tunable Magnetoelectric RF Inductors

Abstract

A great challenge in power/RF electronics has been achieving integrated magnetic inductors with high quality factor ( $Q$ -factor) and high inductance density at gigahertz frequencies. In this article, integrated solenoid magnetoelectric inductors based on FeGaB/Al2O3 multilayer as the magnetic core are designed to operate at high gigahertz frequencies, high $Q$ -factor, and inductance tunability. A high self-resonant frequency of >3 GHz with a flat inductance of 1.4 nH and a peak $Q$ -factor of ~32.7 has been achieved within a wide operating frequency ranging from 0.3 to 3 GHz with magnetic annealing treatment to enhance the inductance density and $Q$ -factor. Two different inductance-tuning methods are tested. For magnetic field tuning, an external magnetic field from 0 to 500 Oe is applied to achieve an inductance tunability $\Delta {\mathbf {L}/\mathbf {L}} _{\mathbf {min}}$ of ~69.2%. Voltage tuning is also tested based on the magnetoelectric coupling between FeGaB/Al2O3 multilayer and ferroelectric slab achieving a maximum tunability of 191% with a flat inductance within the operating frequency. Such a high $Q$ -factor and high inductance density together with giant electrical tunability will greatly improve the integration level and performance of tunable radio frequency integrated circuits while reducing their power consumption and cost.