Title :
A predistortion linearizer using a tunable resonator
Author :
Gupta, Navin ; Tombak, Ali ; Mortazawi, Amir
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., Univ. of Michigan, Ann Arbor, MI, USA
Abstract :
In this letter, a novel predistortion topology using a tunable resonator is presented. The core of the circuit is a series tunable resonator employing a reverse biased varactor diode. The junction capacitance of the varactor diode increases with RF input power, effectively shifting the resonant frequency of the circuit. This results in the amplitude and phase deviations at the frequency of operation. A 1.8-GHz power amplifier (PA), with a gain of 9 dB and 21-dBm output power, is linearized based on this technique. A maximum of 11 dB improvement in adjacent channel power ratio and an increase in 1.8 dB for the compression point is measured for the linearized PA.
Keywords :
capacitance; circuit tuning; linearisation techniques; power amplifiers; resonators; varactors; 1.8 GHz; 9 dB; RF input power; adjacent channel power ratio; amplitude deviations; circuit core; circuit resonant frequency; junction capacitance; phase deviations; power amplifier; predistortion linearizer; predistortion topology; reverse biased varactor diode; tunable resonator; Capacitance; Circuit topology; Diodes; Power amplifiers; Predistortion; RLC circuits; Radio frequency; Resonant frequency; Tunable circuits and devices; Varactors; Linearization; power amplifiers; predistortion; varactor diode;
Journal_Title :
Microwave and Wireless Components Letters, IEEE
DOI :
10.1109/LMWC.2004.832073