Design Technologies for Silicon-Based High-Efficiency RF Power Amplifiers:A Brief Overview

This paper presents a brief overview of several promising design technologies for high efficiency silicon-based radio frequency （RF） power amplifiers （PAs） as well as the use of these technologies in mobile broadband wireless communications. Four important aspects of PA design are addressed in this paper. First, we look at class-E PA design equations and provide an example of a class-E PA that achieves efficiency of 65-70% at 2.4 GHz. Then, we discuss state-of-the-art envelope tracking （ET） design for monolithic wideband RF mobile transmitter applications. A brief overview of Doherty PA design for the next-generation wireless handset applications is then given. Towards the end of the paper, we discuss an inherently broadband and highly efficient class-J PA design targeting future multi-band multi-standard wireless communication protocols.

Stress Controlled Silicon Nitride Thin Film Deposited by Plasma Enhanced Chemical Vapour Deposition

SiN, films are deposited on silicon wafers through plasma enhanced chemical vapor deposition （PECVD）. The relationship between the film stress and deposition factors is investigated. It is found that low stress films would be obtained by adjusting the ratio of low frequency（LF） power to high frequency（HF） power pulse time or the chamber pressure. The best of the two methods to control stress in the film is changing the percentage of LF power pulse time. The low stress condition is achieved when the percentage of low frequency power pulse time in total time（LF and HF pulse time） is close to 40%, The low stress cantilever of tunable vertical cavity surface emitting laser is obtained by using this deposition condition,

The influence of RF power on the electrical properties of sputtered amorphous InGa-Zn-O thin films and devices

The influence of radio frequency（RF） power on the properties of magnetron sputtered amorphous indium gallium zinc oxide（a-IGZO） thin films and the related thin-film transistor（TFT） devices is investigated comprehensively.A series of a-IGZO thin films prepared with magnetron sputtering at various RF powers are examined.The results prove that the deposition rate sensitively depends on RF power.In addition,the carrier concentration increases from 0.91 x 1019 to 2.15 x 1019 cm-3 with the RF power rising from 40 to 80 W,which may account for the corresponding decrease in the resistivity of the a-IGZO thin films.No evident impacts of RF power are observed on the surface roughness,crystalline nature and stoichiometry of the a-IGZO samples.On the other hand,optical transmittance is apparently influenced by RF power where the extracted optical band-gap value increases from 3.48 to 3.56 eV with RF power varying from 40 to 80 W,as is supposed to result from the carrierinduced band-filling effect.The rise in RF power can also affect the performance of a-IGZO TFTs,in particular by increasing the field-effect mobility clearly,which is assumed to be due to the alteration of the extended states in a-IGZO thin films.