A New Method for Increasing Quality Factor in Active Filters

Abstract

In this paper, we present a new method increasing quality factor of active filter structure in the literature and a new designed filter. The new method is easily applied to all different filter modes with the proper feedback circuit. The center frequency of the filter remains constant as quality factor of filter increases. Also, quality factor can be also tuned electronically by changing the biasing current of the feedback circuit. Furthermore, the performance of the method is demonstrated by CMOS simulation of differential voltage current conveyor and transconductance amplifier. Quality factor value of the filter can also be easily adjusted electronically between 1 and 20 with the presented method. Finally, an application example of the presented method is presented for double tuned amplifier for intermediate frequency pre-amplifier of FM receiver.