文档介绍：Class D voltage-switching MOSFET power amplifier
. Kazimierczuk, PhD, DSc
Indexing terms: Ampl$ers, Inverters, Power electronics
DC/DC resonant convertors. In many applications, the
Abstract: An analysis of a class D voltage- output power or the output voltage should be controlled.
switching tuned power amplifier is given, along This can be plished by varying the operating fre-
with experimental results. Analytical equations are quencyf (FM control).
derived for performance parameters at any oper- The purpose of this paper is to derive analytical equa-
ating frequency normalised with respect to the tions describing the operation of the class D voltage-
resonant frequency and at any load resistance nor- switching amplifier at any operating frequency
malised with respect to the characteristic imped- normalised with respect to the resonant frequency, and
ance of the resonant circuit. The analysis is carried for any normalised load resistance normalised to the
out under the high loaded quality factor assump- characteristic impedance of the resonant circuit. There is
tion, using Fourier series techniques. The behav- a strong need of such material to provide easy-to-use
iour of power MOSFETs in class D circuits for design tools.
both capacitive and inductive loads is discussed in
detail. It is shown that the operation above the
2 Circuit description
resonant frequency (an inductive load) is preferred.
The theoretical results were in good agreement A circuit of the class D voltage-switching resonant ampli-
with measured circuit performance parameters. fier is shown in Fig. 1. It consists of two bidirectional
The equations provide easy-to-use design tools, switches SI and S, and a series-resonant circuit L-C-R,.
which can find a broad application, . in design- Each switch posed of a transistor and an anti-
ing DC/DC resonant converters and DC/AC parallel diode and can conduct either positive or negativ