LINEARIZATION OF BROADBAND TWO-WAY MICROSTRIP DOHERTY AMPLIFIER

The linearization of a broadband two-way microstrip Doherty amplifier designed for application in the frequency range 0.9-1.0 GHz is considered in this paper. The amplifier characterized by the maximum output power 8 W is designed in microstrip technique for broadband applications. For linearization purposes, the second- and fourth-order nonlinear signals are extracted at the output of the peaking cell, adjusted in amplitude and phase and fed at the input and output of the carrier transistor over the microstrip hairpin band-pass filters. The effects of the linearization are considered through the simulation for two sinusoidal signals with different frequency interval between them setting on from 5 MHz and going up to30 MHz at different input power levels up to saturation, as well as for an Orthogonal frequency division multiplexing (OFDM) digitally modulated signal.