Multilayer techniques for MMICs

MMICs still use large numbers of passive components, both lumped elements (spiral inductors and overlay capacitors) and transmission lines and couplers. The area consumed by these can be drastically reduced by the use of multilayer techniques. However, producing MMICs with 3 or more metal layers requires research into the fabrication techniques as well as investigating the modelling and design problems. This paper describes these multilayer techniques which are expected to facilitate an increase in the packing density of commercially fabricated MMICs in the future.