Means and Methods for Building-up the Linearity of Broadband Amplifiers

This article is devoted to the issues related to engineering implementation of methods for building-up the linearity of transmitters and mathematical methods for correcting the parametric non-linear distortions of power amplifiers. Methods for constructing broadband power amplifiers for short-wave transmitters with various types of modulation during information transmission. Possible ways of implementing the various methods of automatic system for monitoring the parameters of a power amplifier in accordance to a specified level of linearity and amplitude response. The problem of obtaining high linearity of a power amplifier and the possibility of its solution by various methods or their combination is determined. Methods of preemphasis of the signal fed to the input of a power amplifier and the precorrection of the modulus of transmission coefficient of a power amplifier are investigated. It is shown that the use of these methods makes it possible to obtain a high path linearity and high efficiency, however they are difficult to implement, and therefore are not currently suitable for use in portable equipment. The greatest attention is paid to the method of using reverse feedback between the signal envelopes at the power amplifier input and output. This method of building-up the linearity of a power amplifier turns out to be preferable for paths of small transmitters.