Design of Variable Active Inductor with Feedback LC-Resonator for Improvement of Q-Factor and Tuning of Operating Frequency

Q 지수의 개선과 동작 주파수 조절을 위해 궤환 LC-공진기를 이용한 가변 능동 인덕터의 설계

  • Seo, Su-Jin (IDEC W.G. & Dept. of Info. And Comm. Engineering, Chonbuk National University) ;
  • Ryu, Nam-Sik (XRONet Corporation) ;
  • Choi, Heung-Jae (IDEC W.G. & Dept. of Info. And Comm. Engineering, Chonbuk National University) ;
  • Jeong, Yong-Chae (IDEC W.G. & Dept. of Info. And Comm. Engineering, Chonbuk National University)
  • 서수진 (전북대학교 전자정보공학부 & 반도체설계교육센터) ;
  • 유남식 (㈜카이로넷) ;
  • 최흥재 (전북대학교 전자정보공학부 & 반도체설계교육센터) ;
  • 정용채 (전북대학교 전자정보공학부 & 반도체설계교육센터)
  • Published : 2008.03.31


In this paper, a new variable active inductor using a conventional grounded active inductor with feedback variable LC-resonator is proposed. The grounded active inductor is realized by the gyrator-C topology and the variable LC-resonator is realized by the low-Q spiral inductor and varactor. This variable LC-resonator can compensate the degradation of Q-factor due to parasitic capacitance of a transistor, and the frequency range with high Q-factor is adjustable by resonance frequency adjustment of LC-resonator. The fabricated variable active inductor with Magnachip $0.18{\mu}m$ CMOS process shows that high-Q frequency range can be adjusted according to varactor control voltage from 4.66 GHz to 5.45 GHz and Q-factor is higher than 50 in the operating frequency ranges. The measured inductance at 4.9GHz can be controlled from 4.12 nH to 5.97 nH by control voltage.


Grounded Active Inductor;Spiral Inductor;Gyrator-C;Variable LC-Resonator;Varactor


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