Study and Design of Electrically Tunable Filter
You Zhi-gang · Communications technology · 2011
In this paper,a tunable filter circuit is described and the specific reasons of inductively coupled and parallel resonant circuit are explained.The equivalent circuit of varactor diodes is given,and the maximum frequency tuning range of filter constituted with varactor diodes is analyzed.AVHF-band electrically tunable filter with ADS software by agilent is designed and its operation band is 100～260 MHz,pass-band insertion loss 4dB,VSWR 1.65.The changes of the filter insertion loss and rectangular coefficient in the adjustable frequency range are analyzed.And the experimental result is fairly consistent with the above theoretical analysis.