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Abstract

This paper presents a flexible and generic broadband RF predistortion linearizer designed using backward reflection topology that can correct for the dualinflection point type compression characteristics usually encountered in the gain profile of metal semiconductor field effect transistor (MESFET) based power amplifiers. It employs circuit configuration of two parallel Schottky diodes with one p-intrinsic-n (PIN) diode in parallel, connected at two ports of a 90°hybrid coupler. The Schottky diodes are coupled via a quarter wave transmission line segment which generates dual inflection points in the gain characteristics of the linearizer. The incorporation of a PIN diode helps in improving the achievable range in the gain and phase characteristics of the linearizer. Overall, the linearizer is capable of linearizing various types of power amplifiers owing to the flexible control on the linearizer's parameters and eventually the gain and phase characteristics of the linearizer. The proposed linearizer can be employed in the frequency range of 1.4-2.8 GHz and can simultaneously improve the third- and fifth-order intermodulation distortions. The measurements carried out on a commercial ZHL-4240 gallium arsenide field effect transistor (GaAs FET) based power amplifier demonstrates the broadband functionality of the proposed linearizer.

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Dr. Mohammad S. Hashmi

Dr. Zaharia S. Rogojan

Dr. S. R. Nazifi

Dr. Fadhel M. Ghannouchi