Journal of the Institute of Electronics Engineers of Korea TC (대한전자공학회논문지TC)

The Institute of Electronics and Information Engineers (대한전자공학회)
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The Design of Predistortion Linearizer using the Low Frequency Intermodulation Terms of Harmonic Generator

Harmonic Generator의 저주파 혼변조 신호 성분을 이용한 전치왜곡 선형화기 설계

  • Kim, Young (Dept. of Electronics Engineering, Sogang University) ;
  • Chang, Ik-Soo (Dept. of Electronics Engineering, Sogang University) ;
  • Jang, Hyung-Soon (Dept. of Electronics Engineering, Sogang University)
  • 김영 (西江大學校 電子工學科) ;
  • 장익수 (西江大學校 電子工學科) ;
  • 장형순 (西江大學校 電子工學科)
  • Published : 2002.09.01
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Abstract

In this paper, a new type predistorter using a low frequency intermodulation signals terms of harmonic generator is proposed. A vector modulator, in which fundamental signal is modulated with low frequency intermodulation signals derived from harmonic generator, generates predistorted third and fifth IM components. Using predistorted signals, intermodulation distortion signals of power amplifier suppressed. The suggested predistorter has been manufactured to operate in Korean PCS base-station transmitting band (1840~1870MHz). The test results show that the third IMD signal level is reduced more than 20dB and the fifth IMD signal is reduced about 10dB for CW two-tone signals. The predistorter improves the Adjacent Channel Power Ratio (ACPR) more than 10dB for CDMA (IS-95) signals.

본 논문에서 제시한 새로운 형태의 전치왜곡 회로는 Harmonic Generator에서 발생되는 저주파 혼변조 신호 성분만을 추출하여, 이것을 Vector Modulator에서 원 신호와 진폭 변조시키는 것이다. 이러한 회로를 이용하여 3차, 5차 혼변조 신호를 발생시켜 전력 증폭기의 혼변조 신호를 감쇠시키는 선형화기를 구현하였다. 구현된 전치왜곡 선형화기는 국내 개인 휴대 통신(PCS) 기지국 송신 대역인 1840MHz~1870MHz주파수에서 동작되도록 제작, 측정을 하였다. 그 결과 반송파 2-tone 신호를 인가할 때 3차 혼변조 왜곡 특성은20dB 이상, 5차 혼변조 왜곡 특성은 10dB 이상의 개선효과를 얻었고, IS-95 CDMA 신호를 인가하였을 때 인접채널 전력 비를 10dB이상 개선시켰다.

Keywords

References

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