In this study, we investigated the resonance mechanism of 6.78 MHz resonant wireless power transfer (WPT) systems. The depletion mode a gallium nitride high-electron-mobility transistor (GaN HEMT) was used to switch states in class-E amplifier circuit high frequency. D-mode GaN HEMT without body diode prevented current leakage from capacitor when drain-source voltage became negative. zero-volta...

A power amplifier structure is presented that has a low output variation against the load impedance at 6.78 MHz using two Class E amplifiers and λ/4 transmission line. with another high are connected in parallel phase difference of 90° Each generates same under nominal conditions to achieve maximum efficiency. The can be reduced during operation, which increases from one decreases time when cha...

13 watt Current Mode Class-D (CMCD) with 60% efficiency is presented. This amplifier is the highest power switch mode microwave power amplifier reported to date. The CMCD architecture is an improvement over the Voltage Mode Class-D in that the parasitic reactance in the active device can be absorbed into the tank circuit resulting in a zero voltage switching condition.

A new symmetrical topology switching power amplifier is introduced for professional audio use. The amplifier is composed by a pair of semi soft switched half-bridges with independent feedback control. Whole overall layout looks very similar than an already bridge configured stereo amplifier with few exceptions. Although the complexity of the proposed topology is at least twice of the convention...

Date The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline. Multifunctional RF front ends need to transmit signals with varying peak-to-average ratios requiring high linearity which often implies low efficiency. This thesis studies high-efficien...

Class D power amplifiers, one of the most critical devices for application in sound systems, face severe challenges due to increasing requirement smartphones, digital television, sound, and other terminals. The audio amplifier has developed from a transistor field-effect tube amplifier, amplifiers have made significant progress circuit technology, components, ideological understanding. stumblin...

This paper investigates the design curves of class E amplifier with nonlinear capacitance for any output Q and finite dc-feed inductance. The important results are; 1) the capacitance nonlinearity strongly affects the design parameters for low Q, 2) the value of dc-feed inductance is hardly affected by the capacitance nonlinearity, and 3) the input voltage is an important parameter to design cl...

approved: Andreas Weisshaar In cellular telephones, RF power amplifiers consume a significant part of the total phone current. Reducing the average PA current will extend battery life. In GSM systems the handset is commanded by the base station to transmit at power levels lower than full power much of the time. A Doherty amplifier can be used to improve efficiency at these lower power levels, p...