Implementation of a Linearized Power Amplifier using a Adaptive Digital Predistorter

적응 디지틀 전치왜곡기를 이용한 선형화된 전력증폭기의 구현

  • 류봉렬 (금성사 영상미디어 연구소 ATV 그룹) ;
  • 정창규 (연세대학교 전자공학과) ;
  • 김남수 (청주대학교 정보통신공학과) ;
  • 박한규 (연세대학교 전파공학과)
  • Published : 1994.12.01

Abstract

In this paper, the linearized power amplifier using digital adaptive predistorter is implemented in order to restrict spectral spreading and adjacent channel interference. The linearized systems is composed of a DSP56001 processor that executes predistortion in baseband. 90.deg. phase shifter, power splitter/combiner, quadrature modulator/demodulator of 360MHz band, and nonlinear amplifier. A ${\pi}$/4-shift QPSK is used to modulate digital random signals. As the quantized power of baseband signal and the output of amplifier are fed to the predistorter, and predistorting values are calculated using an adaptive algorithm. In the experiment, a peak to sidelobe ratio of the linearized amplifier is improved up to 15dB in comparison with conventional nonlinear amplifier, which means that the distortion of transmitted signal is decreased and adjacent channel interference was reduced.

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