Low Resistance Integrated Toroidal Inductors for Power Management

Abstract

5.6×5.6×0.5mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> integrated toroidal inductors with high L/R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DC</sub> ratio have been fabricated on Si substrates with microelectronics tools. The realization features thick layer Cu and Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">80</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sub> technologies. Impedance measurements have been performed up to 100MHz. As a typical result, we show an inductor with L~500nH up to 10MHz, R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DC</sub> ~110mΩ. To our knowledge, it is the best compromise shown so far. This demonstrates the interest of such integrated inductors to replace discrete ferrite inductors for compact power modules for mobile communication circuits.