Characterization and Implementation Methods of Multilayer Inductors with Ni-Zn Ferrite and Carbonyl SF Powder Iron on Ceramic Substrates for RF Amplifers

Abstract

Characterization and implementation of multilayer inductors constructed with Ni-Zn ferrite and Carbonyl SF powder iron on ceramic substrates for radio frequency (RF) power amplifier applications are presented for the first time. The multilayer inductor has a base material with high permittivity and low loss ceramic substrate, which has spiral inductor configuration and overlay magnetic substrate that is used to increase the effective permeability of the multilayer structure. High permittivity and low loss ceramic substrate gives the inductor a lower profile and better thermal performance for radio frequency applications. Ni-Zn ferrite and Carbonyl SF powder iron magnetic layers are used as an overlay magnetic substrate to increase effective permeability of the multilayer structure where magnetic flux flows through without degrading the performance of the inductor. The multilayer inductors that are designed are used as resonator inductor in the load line, RF choke, and combiner output inductor for RF power amplifiers carrying a large amount of current. Several different multilayer inductors are simulated, implemented, and measured. Various characteristic curves such as quality factor, inductance, resonance, return loss, and impedance versus frequency for different permeability and thickness of the magnetic substrate using Ni-Zn ferrite and powder iron core are measured, simulated, and presented. Measured and simulated results have been compared and found to be close. The multilayer inductors are then integrated to the RF amplifier, and the amplifier is tested for performance when it is interfaced with matched load at the rated power. It has been shown that the proposed multilayer inductor design can be used for radio frequency amplifier applications when high current flow and lower profile are required.