High-performance inductors

In this paper, we describe the design, test data, and analysis of several circular spiral inductors fabricated on GaAs substrates using the multifunction self-aligned gate multilayer process. Various factors such as high inductance, high-quality Q, high current handling capacity, and compactness are studied. Several configurations for inductors were investigated to optimize the inductor geometry such as the linewidth, spacing between the turns, conductor thickness, and inner diameter. It includes measured effects of various parameters on inductor performance, such as linewidth, sparing, inner diameter, metal thickness, underlying dielectric, and dielectric thickness. It is shown experimentally that the Q factor of spiral inductors can be enhanced by using 9-mum-thick metallization and placing inductors on a 10-mum-thick polyimide Layer, which is placed on top of the GaAs substrate. Using this technique, we have observed up to 93% improvement in the Q factor of circular spiral inductors, as compared to standard spiral inductors fabricated on GaAs substrates. Inductors having thick metallization can also handle de currents as large as 0.6 A.