Study of fully packaged and power combining power amplifer integrated circuits

Abstract

Nowadays, consumers demand their wireless devices to be compact in size, low cost and high efficiency. Integrating all circuits in a single chip with deep submicron CMOS technology would be a favorable choice. The CMOS technology not only facilitates tiny die size but also exhibits lower fabrication cost with volume production. However, as the transistor size is scaling down, its break-down voltage reduces. It leads to a big challenge in designing power hungry circuits, such as power amplifiers (PAs). Therefore, a lot of attentions have been attracted to tackle the low break-down voltage bottleneck so that all front-end circuits can be integrated together to satisfy consumers' needs. Although several breakthroughs have been made recently, PA design is still among the most challenging. To address this issue, a low cost and fully integrated PA is proposed. By making use of the parasitic on the package, the efficiency and output power of PA can be greatly enhanced. On the other hand, different types of power combiners in IC are compared to further enhance the output power under low voltage condition. Throughout analyzing the trade-off between different combining techniques, a new voltage-mode transformer based power combiner is proposed to boost the transformation ratio such that the whole PA can deliver higher output power and maintain good transfer efficiency. The prototypes of two proposed PAs were implemented with GaAs technology to demonstrate the ideas. Mathematical models and experimental results validate the proposed concept. The first fully packaged PA features 1-Watt output power and 20 dB gain while the power combining PA achieves 2-Watt output power and 19 dB gain. Both techniques can be used in CMOS technology and realize the ultimate goals of low cost, small size and high efficiency wireless devices.

Date of Award	3 Oct 2014
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Chi Hou CHAN (Supervisor)