New RF Magnetic Stripe Inductors With Flanges Based on Exchange-Coupled Magnetic Films

Abstract

This work describes magnetically confined inductors using coplanar waveguide (CPW) lines. The fabrication uses antiferromagnetic exchange coupled iron-cobalt films with high ferromagnetic resonance frequency (5 to 7 GHz). A first type of inductors uses sandwiched lines and exhibits a linear density of inductance of 0.9 nHmiddotmm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . A second type includes magnetic flanges and indicates 1.15 nHmiddotmm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . The influence of the flanges contributes to 30% increase of the intrinsic coupling with the line. The measured inductance (L) and quality factor (Q) perfectly agree with theoretical permeability considerations. With meanders, we show L of ~3 nH which competes standard spiral inductors. We also demonstrate that Q only depends on the intrinsic values of the reference line (Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) and the magnetic material (Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mat</sub> ). Therefore, Q-optimization is possible at high frequency. We indicate a typical maximum of ~10 at 5 GHz