Active inductor design for reconfigurable bandpass microstrip filter applications

Abstract

Herein, the design of an active inductor and its typical application for a reconfigurable band-pass filter circuit are presented. The Active Inductor design consists of a passive variable phase and amplitude compensating network and a highly linear inverting amplifier in order to form a gyrator-C design. The design allows a wide frequency range for tuning the equivalent inductance and resistance values that enable it to be used as a filter design where the inductor equivalent resistance increases and improves signal rejection for band-pass filter applications. As a typical application, first-order active band-pass filter had been designed and prototyped. The simulation and measurement results of the design are compared with the performance results of counterpart designs in literature. From the experimental results, it can be concluded that the proposed design is a suitable model for design of tunable band pass filter circuits. The design has an operation band of 0.7-2.1GHz with the equivalent inductance value of 2.6nH.