Characteristics of GaAs transformers for RFIC applications

Abstract

In this article, stacked transformers, coupling stacked transformers, interleave transformers, and symmetrical transformers on GaAs substrate are systematically studied. Two kinds of stacked transformer are under study. One has the symmetrical electric property while the other one has a better quality factor for the primary port. The stack transformers have achieved the highest coupling coefficient (similar to 0.9) at the cost of lower self-resonance frequency. The interleave transformers have the identical electrical properties for the primary and the secondary ports. However, the layout is incompatible with the differential operation. Oil the other hand, the symmetrical transformer is compatible with the differential operation (aid call have the center-tapped biasing option. The data established here provides a useful design library for the GaAs RFIC. (C) 2008 Wiley Periodicals, Inc.