Design Study of a High Efficiency LDMOS RF Amplifier

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  • Author: Mouqun Dong
High efficiency RF power amplifiers have always been of interest to RF engineers. A large volume of literature on the subject, ranging from theoretical analyses to practical circuit designs, has been published over the years [1-4]. On the theory side, most analyses utilized considerably simplified models for the devices and circuits to make the mathematics involved manageable. These simplifications are necessary, and the analytical results based on them do reveal certain aspects of how to achieve high efficiency. However the actual device and circuit behaviors are often significantly more complex than the idealized assumptions used in the analyses, and several different effects can take place simultaneously at a real circuit operation condition. As a result, the characteristics of practical RF PA circuits do not always correlate well with the analytical predictions.