Current-Division-Based Digital Frequency Tuning for Active RC Filters

Abstract

This manuscript presents a novel digital frequency tuning technique for integrated active RC filters. Unlike the traditional tuning approach of varying the values of the capacitors or resistors, the proposed technique achieves the tuning by varying the currents that flow through the resistors or capacitors. In this manuscript, the current varying is achieved by using a digital-controlled MOSFET-only current division network. This new tuning technique features digital tuning, compact size, and wide tuning range as well as high linearity as demonstrated by transistor-level circuit simulations.