Linealización de amplificadores por prealimentación para UMTS

Abstract

This paper presents the most important concepts in a UMTS feedforward linearization system. The developed system meets the down link UMTS specifications, achieving a ACLRc<-45 dBc, a ACLRLL<-57 dBc, a EVM of 48% and a PCDE of –44 dB. The output power is +27.7 dBm for this application. An efficiency of nearly the 4.5 % has been obtained, being the total consumption of 13.3 W. The most problematic elements, as the error loop amplifier which must have a 1dB compression point 10 dB over the level of the generated signal, have been analyzed. This specification is due to the special characteristics of the UMTS signals as its variable envelope. Moreover, it can be seen that an imperfect cancellation is advisable to improve both output power and ACLR.