Analytical study of an error envelope feedback linearizer
An error envelope feedback linearizer (EEFL) employs the complex envelope of the distortion generated by the power amplifier (PA) as a feedback to control the envelope of the PA input signal; in this way, a sort of predistortion is realized, allowing the reduction of the intermodulation distortion (IMD) produced by the PA. A recently introduced EEFL architecture is investigated in this article from a mathematical point of view; starting from the functional scheme of the linearizer, its response to one- and two-tone excitations is evaluated, allowing a simple estimation of the achievable performances (IMD reduction). The stability issue may constitute a severe limitation for this class of linearizers; by using both the introduced mathematical model and numerical simulations, the stability is investigated in order to obtain better insight into the working mechanism of the EEFL. (C) 2005 Wiley Periodicals, Inc.
linearization power amplifiers feedback systems