UC San Diego

The focus of this dissertation is on the development of high power, monolithically integrated amplifiers for millimeter-wave wireless communication systems utilizing InP DHBT devices. Due to the ever increasing bandwidth requirements of wireless communications systems, the large amount of spectrum available at millimeter-wave frequencies is making these frequency bands increasingly more relevant. This spurs the need for the development of the various circuit and system building blocks required for implementation of reliable communications systems taking advantage of these wide-band channels. The challenges posed in the development of millimeter-wave power amplifier design range from device model development, to circuit design aspects and also compact power combiner design. The large signal nature of power amplifier operation requires device models, which accurately capture the nonlinear and heating effects of the devices used in the power amplifier design. Techniques for the measurement and model extraction of InP DHBT devices for millimeter- wave applications are discussed in detail. As part of the design of a compact millimeter-wave power amplifier, the optimum design of thermal ballasting networks and cascode termination impedances are described. Design tradeoffs in the choice of load resistance for the design are also explained. Using these techniques, a compact power amplifier operating at 72GHz was designed exhibiting 20.6dBm output power and 13.9% PAE. Finally, the design of a novel planar radial power splitter and combiner architecture is described. Transmission lines, vertical transitions and microstrip crossovers required for the implementation of this structure are explained in detail. Using this structure a high power amplifier is designed with a center frequency of 72GHz. This amplifier demonstrates an output power of 24.6dBm along with a PAE of 8.9%