Design of low distortion active inductor and its applications

Abstract

This paper proposes a novel distortion reduction technique for active inductors. A bias current of a MOSFET, which acts as transconductor in an active inductor, is controlled to reduce a distortion of a active inductor. When an input voltage increases, the bias current is decreased by a control circuit. As a result of this control, transconductance of the MOSFET remains constant. An active inductor using this technique is free from distortion caused by a transconductance variation of a MOSFET. The proposed technique is applied to two different conventional active inductors and novel low distortion active inductors are derived. Computer simulations show that distortion of the proposed active inductor is very low. The proposed low distortion active inductors are applied to a second order bandpass filter and a voltage controlled oscillator. Thanks to the proposed technique, distortion of these circuits are reduced and their performance is improved.