Novel diode-based Ka band adjustable predistortion linearizer

In order to compensate for the nonlinear characteristics of different types of power amplifier, a Ka-band adjustable predistortion linearizer is presented. Based on three branches directional coupler, GaAs Schottky diodes, microstrip line and the load resistance, the linearizer can provide different nonlinear signals with changing the voltage bias of the two diodes, electrical length and characteristic impedance of the microstrip line. The simulation and measured results show that linearizer is able to form different kinds of predistortion signals. When the travelling wave tube amplifiers (TWTAs) are used, the linearizer can provide approximate 6.5 dB gain expansion and 46 phase expansion. When the solid state power amplifiers (SSPAs) are used, the linearizer can provide approximate 11 dB gain expansion and 35 phase compression.