Effect of Substrate Orientation on the Growth of Germanium Oxide in Dry Oxygen Ambience

The present investigation deals with the effect of substrate orientation effect on the growth of thermally oxidized Ge. The thermal oxidation was performed at temperature between 375 and 550°C in dry oxygen ambient under atmospheric pressure. The thickness of thermally oxidized Ge films was measured by spectroscopic ellipsometry and the chemical bonding structures were characterized by using x-ray photoelectron spectroscopy (XPS). No orientation dependence was observed for the oxidation at temperature of 375°C while for oxidation at 490 and 550°C, Ge oxidation and GeO desorption rate of (100) orientation yield higher rate than (111). The larger atomic space of (100) orientation explains the higher oxidation and desorption rate at Ge surface

A Review of Highly Efficient Class F Power Amplifier Design Technique in Gigahertz Frequencies

Highly efficient class F power amplifier (PA) in Gigahertz (GHz) frequencies for wireless application is reviewed in this paper. The study focused on the technique used in designing a class F PA especially at GHz frequencies. Several works on the class F PA with different semiconductor technologies from year 2001 to 2016 are discussed. Recent works on class F PA in wireless applications are examined and a comparison of the PA performances of various techniques is presented. Key performance indicators for high efficiency class F PA include power added efficiency (PAE) and output power (Pout)

Design of CMOS Power Amplifier with Resistive Feedback and Notch Filter for UWB Systems

A CMOS power amplifier (PA) with the implementation of the notch filter designed for ultra-wideband (UWB) systems is presented in this paper. The design is consisted of two stages of amplifier involving source follower and common source topologies with a notch filter and an output matching network. Such design is meant for full band UWB applications that utilize the frequency range within 3.1 GHz to 10.6 GHz with the elimination at 5-6 GHz using 0.18 µm CMOS process. The simulation shows that the proposed PA design achieved 19.25 dB maximum gain with 1.8 V power supply. In this work, the achieved input and output return loss ranging from -8.13 dB to -19.19 dB, and -1.68 dB to -16.03 dB, respectively, through full band frequency

Review of Efficiency CMOS Class AB Power Amplifier Topology in Gigahertz Frequencies

This paper reviewed the efficiency of CMOS class AB power amplifier topology especially in gigahertz frequencies. CMOS class AB power amplifier is a compromise between class A and class B in terms of linearity and efficiency between 50% to 78.5%. However, CMOS class AB power amplifier cannot have good linearity and efficiency simultaneously due to the breakdown in gate-oxide voltage and effects from hot carrier. The breakdown of oxide prevents optimum drain signal and the effect from hot carrier will reduce the quality of the overall PA design. Several works from year 1999 to 2019 with different topology such as multiple gated transistor, cascode, feedforward linearization, differential circuit, transformer combining method with common source harmonic termination and combination of a dual-switching transistor with a third harmonic tuning technique are discussed and the performances of the power amplifier are compared. The best three CMOS class AB power amplifier topologies were chosen in terms of high efficiency. The topologies are two stages with integrated input and interstage matching, Doherty amplifier combined with drain modulation based architectures and self-biased cascode topology that obtained power added efficiency of 45%, 43% and 42%, respectively. Key performance indicators for class AB power amplifier include frequency, power added efficiency, gain and output power are also discussed in this paper

Electromagnetic interference on artificial heart pacemaker

Electromagnetic interference (EMI) due to Radio Frequency (RF) is known to cause interference in electronics devices. Interference may cause devices such as pacemaker to malfunctions with potentially adverse consequences. Exposure of electromagnetic interference comes from digital cellular telephones that are commonly used nowadays. This paper describes the preliminary case study on the effect of the EMI interference with a pacemaker. Temperatures were calculated at various frequencies to investigate the effect. Higher temperatures may cause discomfort to the patient