Highly Efficient and Linear Class E SiGe Power Amplifier Design

This paper discusses the design of monolithic RF broadband Class E SiGe power amplifiers (PAs) that are highly efficient and linear. Load-pull measurement data on IBM 7HP SiGe power devices have been made at 900MHz and 2.4GHz and monolithic class E PAs have been designed using these devices to achieve highest power-added-efficiency (PAE) at these frequencies. It is found that high PAE can be achieved for monolithic single-stage Class E PAs designed using high-breakdown SiGe transistors at ~65% (900MHz) and ~40% (2.4GHz), respectively, which are roughly ~10% lower than the device´s maximum PAE values obtained by load-pull tests under optimal off-chip matching conditions. We have also demonstrated that monolithic SiGe class E PAs can be successfully linearized using an open-loop envelope tracking (ET) technique as their output spectra pass the stringent EDGE transmit mask with margins, achieving overall PAE of 44.4% for the linearized PA system that surpasses the < 30% PAE with commercially available GaAs Class AB PAs for EDGE applications. These promising results indicate the feasibility of realizing true single-chip wireless transceivers with on-chip RF SiGe PAs for spectrally-efficient non-constant-envelope modulation schemes