High efficiency and high linearity amplifier by switching technique

Abstract

Many researchers have researched the amplifiers for the high fidelity and high efficiency. The output stage of an amplifier must satisfy a number of special requirements. One is to deliver a specified amount of signal power to a load with acceptably low levels of signal distortion. Another common objective of output-stage design is to minimize the output impedance so that the voltage gain is relatively unaffected by the value of load impedance. A well-designed output stage should achieve these performance specifications while consuming low quiescent power. Moreover, it should not be a major limitation on the frequency response of the amplifier. This paper studies improving the efficiency and linearity of output stage. There are a lot of classes, such as class A, B, AB, C, D, E, F, G, H. It is introduced the kinds of classes in chapter I. In chapter II, it is described that the current mode control feedback is applied to get the good performances of the class D amplifier. It is also proposed that a new circuit of output stage prevents the oscillation by the reverse recovery current of antiparallel diode and parasitic components between output devices and its environment, oscillation. The amplifier performance is as follows. The frequency range is from 5Hz to 50KHz at 4ohm. The efficiency is 90% at full power 80W. A new class A amplifier with a variable power supply presents in chapter III. The amplifier named to class I. The purpose is taking the merits of high efficiency of class D amplifier and high quality of class A. To operate properly, filters to match the frequency response between class A amplifier and class D and two floating low voltage power supply needs. This chapter describes the calculation of the proposed class and the efficiency comparison of one another. The -3dB bandwidth is 3Hz - 100kHz, and the efficiency is 74 percent. An improved high efficiency class I amplifier is proposed in the chapter IV. Modifying the class D amplifier makes the v...