Modelling and design of high-power HBV multipliers

Abstract: This thesis deals with symmetric varactor frequency multipliers for millimetre and sub-millimetre wave applications. Much of the material presented is general and applicable to any type of (symmetric) varactor, but the focus is on the heterostructure barrier varactor (HBV). The basic function and principles of HBVs are explained. This includes current transport mechanisms, elastance modulation and the important parasitic series resistance. Various epitaxial material layer structures employed for HBVs are compared, followed by a description of HBV processing techniques and different device geometries. The focus is then directed towards modelling high-power devices and a closely related investigation of thermal limitations and models for HBVs. The thermal properties are important in the subsequent section dealing with the design of HBV layer structures. HBV frequency multipliers are treated in the last section. Basic multiplier design considerations are discussed, followed by a review of the most common HBV multiplier topologies. Finally, HBV multiplier measurements are described and state-of-the-art results are presented.